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Vitamin A

Vitamin A

Uses

Vitamin A is a fat-soluble vitamin with four major functions in the body: (1) It helps cells reproduce normally—a process called differentiation (cells that have not properly differentiated are more likely to undergo pre-cancerous changes). (2) It is required for vision; vitamin A maintains healthy cells in various structures of the eye and is required for the transduction of light into nerve signals in the retina. (3) It is required for normal growth and development of the embryo and fetus, influencing genes that determine the sequential development of organs in embryonic development. (4) It may be required for normal reproductive function, with influences on the function and development of sperm, ovaries and placenta.

What Are Star Ratings?

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for Why
3 Stars
Anemia
10,000 to 25,000 IU daily
Vitamin A deficiency can contribute to anemia, supplementing with this vitamin may restore levels and improve symptoms.

Deficiencies of iron , vitamin B12 , and folic acid are the most common nutritional causes of anemia.1 Although rare, severe deficiencies of several other vitamins and minerals, including vitamin A ,2 , 3 vitamin B2 ,4 vitamin B6 ,5 , 6 vitamin C ,7 and copper ,8 , 9 can also cause anemia by various mechanisms. Rare genetic disorders can cause anemias that may improve with large amounts of supplements such as vitamin B1 .10 , 11

3 Stars
Childhood Diseases
High doses of vitamin A may be used to treat measles or chicken pox, but only under a doctor's supervision
Vitamin A plays a critical role in proper immune function, it has been used successfully to prevent and treat measles and to treat chicken pox.

Preliminary research shows that supplemental vitamin A improves the likelihood that the measles vaccine will provide protection.12 Vitamin A has, since the 1920s, been the subject of much research into the prevention and treatment of childhood exanthems, particularly measles.13 This nutrient has a critical role in proper immune function , and there is evidence that supplementation with vitamin A reduces the incidence and severity of, and deaths from, childhood measles.14 , 15 The World Health Organization (WHO) has therefore recommended that children with signs of deficiency receive supplementation with vitamin A. The recommended amounts are 100,000 IU for children younger than one year and 200,000 IU for children older than one year, immediately upon diagnosis, and repeated once the next day and once in one to four weeks.16 A controlled trial of African children given vitamin A supplementation according to the WHO’s recommendations found that severity of measles and its long-term consequences were reduced by 82% on day eight, 61% in week six, and 85% six months after the onset.17

Another controlled trial found that giving approximately 200,000 IU of vitamin A once during measles illness was not adequate to provide any benefit in African children whose vitamin A status was unknown.18 In a controlled prevention study, Indian children treated with 2,500 mcg (8,333 IU) of vitamin A weekly had fewer measles complications and less than half of the rate of death as compared with children receiving placebo;19 but in another study, Indian children receiving 200,000 IU of vitamin A every six months did not have a different rate of total infectious illness nor rate of death as compared with children receiving placebo.20

An analysis of 20 controlled trials concluded that vitamin A supplementation reduced deaths from measles respiratory infection by 70%.21 While vitamin A deficiency is widespread in developing countries, it has also been reported in the United States and has been linked with more severe cases of measles.22 The American Academy of Pediatrics has recommended supplementation with vitamin A for children between the ages of six months and two years who are hospitalized with measles and its complications. The recommended amount is a single administration of 100,000 IU for children aged 6 to 12 months and 200,000 IU for children older than 1 year, followed by a second administration 24 hours later and a third after four weeks in children who are likely to have vitamin A deficiency.23

One trial showed that low levels of vitamin A are more prevalent in children with measles than in similar children without measles, with levels rising back to normal several days after the onset of the infection. This observation led the authors of the study to conclude that vitamin A deficiency is a consequence of infection with the measles virus and to recommend supplementation with vitamin A during measles infection even when prior deficiency is not suspected.24 Vitamin A stores have also been shown to be depleted during chicken pox infection,25 and some preliminary data supports its use in treatment of chicken pox. In a controlled trial, in which children without vitamin A deficiency were given either 200,000 IU of vitamin A or placebo one time during chicken pox, the children given vitamin A had shorter duration of illness and fewer severe complications. The researchers then treated the patients’ siblings with vitamin A before chicken pox became evident, and they had an even shorter length of illness.26

3 Stars
Cystic Fibrosis
5,000 to 10,000 IU daily
The fat malabsorption associated with cystic fibrosis often leads to a deficiency of fat-soluble vitamins, such as vitamin A. Supplementing with this vitamin can help counteract the deficiency.

The fat malabsorption associated with CF often leads to a deficiency of fat-soluble vitamins. Oral supplementation of these nutrients is considered crucial to maintaining good nutritional status.27 Current recommendations for supplementation are as follows: vitamin A , 5,000 to 10,000 IU/day; vitamin D , 1,000 to 2,000 IU/day; vitamin E , 100 to 300 IU/day; and vitamin K , 5 mg every three days. Of the water-soluble vitamins, only vitamin B12 is poorly absorbed in cystic fibrosis,28 and taking pancreatic enzymes helps prevent B12 deficiencies.29

3 Stars
Infection
See a doctor for evaluation of possible deficiency
Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms.

Nutrients useful for maintaining healthy immune function are also applicable for preventing infections. Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms.30 However, most research shows that while vitamin A supplementation helps people prevent or treat infections in developing countries where deficiencies are common,31 little to no positive effect, and even slight adverse effects, have resulted from giving vitamin A supplements to people in countries where most people consume adequate amounts of vitamin A.32 , 33 , 34 , 35 , 36 , 37 , 38 Moreover, vitamin A supplementation during infections appears beneficial only in certain diseases. An analysis of trials revealed that vitamin A reduces mortality from measles and diarrhea , but not from pneumonia, in children living in developing countries.39 A double-blind trial for vitamin A supplementation in Tanzanian children with pneumonia confirmed its lack of effectiveness for this condition.40 In general, parents in the developed world should not give vitamin A supplements to children unless there is a reason to believe vitamin A deficiency is likely, such as the presence of a condition causing malabsorption (e.g., celiac disease ). However, the American Academy of Pediatrics recommends that all children with measles should be given high-dose vitamin A for several days.

3 Stars
Leukoplakia
28,500 IU daily under medical supervision
Vitamin A has been shown to be effective against leukoplakia.

Beta-carotene is the most widely used supplement in the treatment of leukoplakia. In a clinical trial of betel nut chewers with leukoplakia, supplementation with 150,000 IU of beta-carotene twice per week for six months significantly increased the remission rate compared with placebo (14.8% vs. 3.0%).41 The effectiveness of beta-carotene for treating leukoplakia was also confirmed in a double-blind trial that used 100,000 IU per day for six months.42 In one trial, supplementation with 33, 333 IU of beta-carotene per day, alone or combined with 50 IU of vitamin E , was reported not to reduce the incidence of leukoplakia.43 These results have also been observed in smaller trials.44 , 45

Drug therapy with a synthetic, prescription form of vitamin A (known as Accutane®, isotretinoin , and 13-cis retinoic acid) has been reported to be more effective than treatment with 50,000 IU per day of beta-carotene.46 However, because of the potential toxicity of the vitamin A-like drug, it may be preferable to treat leukoplakia with beta-carotene, which is much safer.

Before the research on beta-carotene was published, vitamin A was used to treat leukoplakia.47 One group of researchers reported that vitamin A (28,500 IU per day) was more effective than beta-carotene in treating people with leukoplakia.48 Another trial found that the combination of 150,000 IU per week of beta-carotene plus 100,000 IU per week of vitamin A led to a significant increase in remission time compared to beta carotene alone in betel nut chewers.49 Women who are or who could become pregnant should not take 100,000 IU of vitamin A per week without medical supervision.

3 Stars
Measles
200,000 IU daily for two days under medical supervision
In developing countries where vitamin A deficiency is common, preventive supplementation with vitamin A reduced the risk of death in children with measles.

Measles appears to increase the body’s need for vitamin A .50 , 51 Studies in developing countries have shown that measles infection is more frequent and severe in people with low vitamin A blood levels,52 , 53 and preliminary research suggests this may also be true in the developed world.54 , 55 , 56 Repeatedly in controlled trials, preventive supplementation with vitamin A, at oral doses of up to 400,000 IU per day, reduced the risk of death in children with measles living in developing countries.57 , 58 , 59 Whether vitamin A supplementation would help people with measles in developed countries, where deficiency is uncommon, is less clear.60 However, the American Academy of Pediatrics recommends that all children with measles be given a short course of high-dose vitamin A. Two controlled studies of urban South African61 and Japanese62 children hospitalized with severe measles showed that supplementation with 100,000 to 400,000 IU of vitamin A resulted in faster recoveries, fewer complications, and fewer pneumonia-related deaths. An older study in England found one ounce per day of cod liver oil (containing about 40,000 IU of vitamin A, plus vitamin D and omega-3 fatty acids) reduced measles-related deaths in children hospitalized with severe cases of the disease.63 Such large doses of vitamin A should only be taken under a doctor’s supervision.

3 Stars
Night Blindness
If deficient: 10,000 to 25,000 IU daily
Night blindness may be an early sign of vitamin A deficiency. Doctors often recommend supplementing with vitamin A per day to correct a deficiency.

Night blindness may be an early sign of vitamin A deficiency.64 , 65 Such a deficiency may result from diets low in animal foods (the main source of vitamin A), such as eggs, dairy products, organ meats, and some fish. Low intake of fruits and vegetables containing beta-carotene , which the body converts into vitamin A, may also contribute to a vitamin A deficiency. Doctors often recommend 10,000 to 25,000 IU of vitamin A per day to correct a deficiency. Beta-carotene is less effective at correcting vitamin A deficiency than is vitamin A itself, because it is not absorbed as well and is only slowly converted by the body into vitamin A.

2 Stars
Celiac Disease
Consult a qualified healthcare practitioner
Vitamin A deficiency may occur as a result of celiac disease, in which case vitamin A supplements or injections can be beneficial.

In one study, six people with diet-treated celiac disease had abnormal dark-adaptation tests (indicative of “night blindness”), even though some were taking a multivitamin that contained vitamin A . Some of these people showed an improvement in dark adaptation after receiving larger amounts of vitamin A, either orally or by injection.66 People with celiac disease should discuss the possibility of vitamin A deficiency with a healthcare practitioner before taking vitamin A supplements.

2 Stars
Heart Attack
50,000 IU daily
Taking vitamin A may reduce heart attack risk and may improve the outcome for people who have already had a heart attack.

Blood levels of the antioxidant nutrients vitamins A, C, and E, and beta-carotene are reported to be lower in people with a history of heart attack, compared with healthy individuals.67 The number of free radical molecules is also higher, suggesting a need for antioxidants. Streptokinase, a drug therapy commonly used immediately following a heart attack, enhances the need for antioxidants.68

Taking antioxidant supplements may improve the outcome for people who have already had a heart attack. In one double-blind trial, people were given 50,000 IU of vitamin A per day, 1,000 mg of vitamin C per day, 600 IU of vitamin E per day, and approximately 41,500 IU of beta-carotene per day or placebo.69 After 28 days, the infarct size of those receiving antioxidants was significantly smaller than the infarct size of the placebo group.

Low levels of beta-carotene in fatty tissue have been linked to an increased incidence of heart attacks, particularly among smokers.70 One population study found that eating a diet high in beta-carotene is associated with a lower rate of nonfatal heart attacks.71 However, beta-carotene supplementation may not offer the same protection provided by foods that contain beta-carotene. Most,72 , 73 but not all, trials74 have found that supplemental beta-carotene is not associated with a reduced risk of heart attacks.

2 Stars
Immune Function
Consult a qualified healthcare practitioner
Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms.

Vitamin A plays an important role in immune system function and helps mucous membranes, including those in the lungs, resist invasion by microorganisms.75 However, most research shows that while vitamin A supplementation helps people prevent or treat infections in developing countries where deficiencies are common,76 little to no positive effect, and even slight adverse effects, have resulted from giving vitamin A supplements to people in countries where most people consume adequate amounts of vitamin A.77 , 78 , 79 , 80 , 81 , 82 , 83 Moreover, vitamin A supplementation during infections appears beneficial only in certain diseases. An analysis of trials revealed that vitamin A reduces mortality from measles and diarrhea , but not from pneumonia, in children living in developing countries.84 A double-blind trial of vitamin A supplementation in Tanzanian children with pneumonia confirmed its lack of effectiveness for this condition.85 In general, parents in the developed world should not give vitamin A supplements to children unless there is a reason to believe vitamin A deficiency is likely, such as the presence of a condition causing malabsorption (e.g., celiac disease ). However, the American Academy of Pediatrics recommends that all children with measles be given short-term supplementation with high-dose vitamin A in cases of hospitalization, malnutrition, and other special circumstances determined by a doctor.86

A combination of antioxidants vitamin A , vitamin C , and vitamin E significantly improved immune cell number and activity compared with placebo in a group of hospitalized elderly people.87 Daily intake of a 1,000 mg vitamin C plus 200 IU vitamin E for four months improved several measures of immune function in a preliminary study.88 To what extent immune-boosting combinations of antioxidants actually reduce the risk of infection remains unknown.

2 Stars
Iron-Deficiency Anemia (Iron)
Consult a qualified healthcare practitioner
Taking vitamin A and iron together has been reported to help overcome iron deficiency more effectively than iron supplements alone.

Taking vitamin A and iron together has been reported to help overcome iron deficiency more effectively than iron supplements alone.89 Although the optimal amount of vitamin A needed to help people with iron deficiency has yet to be established, some doctors recommend 10,000 IU per day.

2 Stars
Menorrhagia
50,000 IU of vitamin A each day taken under the supervision of a doctor
In one study, women with menorrhagia who took vitamin A showed significant improvement or complete normalization of menstrual blood loss.

In a study of women with menorrhagia who took 25,000 IU of vitamin A twice per day for 15 days, 93% showed significant improvement and 58% had a complete normalization of menstrual blood loss.90 However, women who are or could become pregnant should not supplement with more than 10,000 IU (3,000 mcg) per day of vitamin A.

2 Stars
Peptic Ulcer
Take under medical supervision: 150,000 IU per day
Vitamin A is needed to heal the linings of the stomach and intestines. In one trial, supplementing with vitamin A improved healing in a small group of people with stomach ulcer.

Vitamin A is needed to heal the linings (called mucous membranes) of the stomach and intestines. In one controlled trial, vitamin A supplementation facilitated healing in a small group of people with stomach ulcer.91 The amount used in that study (150,000 IU per day) can be toxic and may also cause birth defects. Such a high dose should not be taken by a pregnant woman, by a woman who could become pregnant , or by anyone else without careful supervision from a doctor. Objective evidence of ulcer healing from taking vitamin A has been reported by the same research group.92 The effect of lower amounts of vitamin A has not been studied in people with peptic ulcer.

2 Stars
Severe Measles
Consult a qualified healthcare practitioner
Two studies of children with severe measles showed that supplementing with high doses vitamin A speeded recovery and reduced complications and pneumonia-related deaths.

Vitamin A has a critical role in proper immune function , and evidence suggests that supplementing with it reduces the incidence and severity of, and deaths from, childhood measles.93 , 94 The World Health Organization (WHO) has therefore recommended that children with signs of deficiency receive supplementation with vitamin A. The recommended amounts are 100,000 IU for children younger than one year and 200,000 IU for children older than one year, immediately upon diagnosis, and repeated once the next day and once in one to four weeks.95 A controlled trial of African children given vitamin A supplementation according to the WHO’s recommendations found that severity of measles and its long-term consequences were reduced by 82% on day eight, 61% in week six, and 85% six months after the onset.96

Another controlled trial found that giving approximately 200,000 IU of vitamin A once during measles illness was not adequate to provide any benefit in African children whose vitamin A status was unknown.97 In a controlled prevention study, Indian children treated with 2,500 mcg (8,333 IU) of vitamin A weekly had fewer measles complications and less than half of the rate of death as compared with children receiving placebo;98 but in another study, Indian children receiving 200,000 IU of vitamin A every six months did not have a different rate of total infectious illness nor rate of death as compared with children receiving placebo.99

An analysis of 20 controlled trials concluded that vitamin A supplementation reduced deaths from measles respiratory infection by 70%.100 While vitamin A deficiency is widespread in developing countries, it has also been reported in the United States and has been linked with more severe cases of measles.101 The American Academy of Pediatrics has recommended supplementation with vitamin A for children between the ages of six months and two years who are hospitalized with measles and its complications. The recommended amount is a single administration of 100,000 IU for children aged 6 to 12 months and 200,000 IU for children older than 1 year, followed by a second administration 24 hours later and a third after four weeks in children who are likely to have vitamin A deficiency.102

One trial showed that low levels of vitamin A are more prevalent in children with measles than in similar children without measles, with levels rising back to normal several days after the onset of the infection. This observation led the authors of the study to conclude that vitamin A deficiency is a consequence of infection with the measles virus and to recommend supplementation with vitamin A during measles infection even when prior deficiency is not suspected.103 Vitamin A stores have also been shown to be depleted during chicken pox infection,104 and some preliminary data supports its use in treatment of chicken pox. In a controlled trial, in which children without vitamin A deficiency were given either 200,000 IU of vitamin A or placebo one time during chicken pox, the children given vitamin A had shorter duration of illness and fewer severe complications. The researchers then treated the patients’ siblings with vitamin A before chicken pox became evident, and they had an even shorter length of illness.105

2 Stars
Wound Healing
Take under medical supervision: 25,000 IU daily
Vitamin A plays a central role in wound healing and may be useful as a supplement or in a topical ointment.

Vitamin A plays a central role in wound healing,106 but the effect of supplemental vitamin A in people who have suffered a minor injury and are not vitamin A-deficient remains unclear. Vitamin A supplements have been shown to improve healing in animal studies,107 and may be especially useful in a topical ointment for skin injuries in people taking corticosteroid medications.108 Although there are no studies in humans, some doctors recommend 25,000 IU of vitamin A per day, beginning two weeks prior to surgery and continuing for four weeks after surgery.

1 Star
Abnormal Pap Smear
Refer to label instructions
Women who don’t get enough vitamin A have an increased risk of cervical dysplasia, though there is little research on using vitamin A as a treatment.

Women with a low intake of vitamin A have an increased risk of cervical dysplasia.109 However, there is little research on the use of vitamin A as a treatment for cervical dysplasia.

1 Star
Acne Vulgaris
Refer to label instructions
Under medical supervision, large quantities of vitamin A have been used successfully to treat severe acne. However, the acne typically returns after treatment is discontinued.

Large quantities of vitamin A —such as 300,000 IU per day for females and 400,000–500,000 IU per day for males—have been used successfully to treat severe acne.110 However, unlike the long-lasting benefits of the synthetic prescription version of vitamin A ( isotretinoin as Accutane), the acne typically returns several months after natural vitamin A is discontinued. In addition, the large amounts of vitamin A needed to control acne can be toxic and should be used only under careful medical supervision.

1 Star
Alcohol Withdrawal
Refer to label instructions
Because of potential liver damage, correcting the vitamin A deficiency common to alcoholics requires a doctor’s supervision to monitor liver function.

Although the incidence of B-complex deficiencies is known to be high in alcoholics, the incidence of other vitamin deficiencies remains less clear.111 Nonetheless, deficiencies of vitamin A , vitamin D , vitamin E , and vitamin C are seen in many alcoholics. While some reports have suggested it may be safer for alcoholics to supplement with beta-carotene instead of vitamin A,112 potential problems accompany the use of either vitamin A or beta-carotene in correcting the deficiency induced by alcoholism.113 These problems result in part because the combinations of alcohol and vitamin A or alcohol and beta-carotene appear to increase potential damage to the liver. Thus, vitamin A-depleted alcoholics require a doctor’s intervention, including supplementation with vitamin A and beta-carotene accompanied by assessment of liver function. Supplementing with vitamin C, on the other hand, appears to help the body rid itself of alcohol.114 Some doctors recommend 1 to 3 grams per day of vitamin C.

1 Star
Conjunctivitis and Blepharitis
Refer to label instructions
Vitamin A deficiency has been reported in people with chronic conjunctivitis, but it is unknown whether vitamin A supplementation can help the condition.

Vitamin A deficiency has been reported in people with chronic conjunctivitis.115 It is unknown whether vitamin A supplementation can prevent conjunctivitis or help people who already have the condition.

1 Star
Crohn’s Disease
Refer to label instructions
Vitamin A is needed for the growth and repair of cells that line both the small and large intestine and can improve symptoms in people with Crohn’s disease.

Vitamin A is needed for the growth and repair of cells that line both the small and large intestine.116 At least two case reports describe people with Crohn’s disease who have responded to vitamin A supplementation.117 , 118 However, in one trial, vitamin A supplementation failed to maintain remission of the disease.119 Therefore, although some doctors recommend 50,000 IU per day for adults with Crohn’s disease, this approach remains unproven. An amount this high should never be taken without qualified guidance, nor should it be given to a woman who is or could become pregnant .

1 Star
Diarrhea
Refer to label instructions
Only in cases of malabsorption should vitamin A be used to treat diarrhea, as it has been shown to have no effect or to increase risk of diarrhea in well-nourished children.

It is known vitamin A supplements support immune function and prevent infections. This is true, however, only under some circumstances. Vitamin A supplementation can also increase the risk of infections, according to the findings of a double-blind trial.120 In a study of African children between six months and five years old, a 44% reduction in the risk of severe diarrhea was seen in those children given four 100,000–200,000 IU supplements of vitamin A (the lower amount for those less than a year old) during an eight-month period. On further investigation, the researchers discovered that the reduction in diarrhea occurred only in children who were very malnourished. For children who were not starving, vitamin A supplementation actually increased the risk of diarrhea compared with the placebo group. The vitamin A-supplemented children also had a 67% increased risk of coughing and rapid breathing, and signs of further lung infection, although this problem did not appear in children infected with the AIDS virus. These findings should be of concern to American parents, whose children are not usually infected with HIV or severely malnourished. Such relatively healthy children fared poorly in the African trial in terms of both the risk of diarrhea and the risk of continued lung problems. Vitamin A provided no benefit to the well-nourished kids. Therefore, it makes sense not to give vitamin A supplements to children unless there is a special reason to do so, such as the presence of a condition causing malabsorption (e.g., celiac disease ).

1 Star
Gastritis
Refer to label instructions
Vitamin A appears to reduce ulcer size and pain in people with ulcers and may help treat gastritis.

Zinc and vitamin A , nutrients that aid in healing, are commonly used to help people with peptic ulcers. For example, the ulcers of people taking 50 mg of zinc three times per day healed three times faster than those of people who took placebo.121 Since some types of gastritis can progress to peptic ulcer, it is possible that taking it may be useful. Nevertheless, the research does not yet show that zinc specifically helps people with gastritis. The amount of zinc used in this study is very high compared with what most people take (15–40 mg per day). Even at these lower levels, it is necessary to take 1–3 mg of copper per day to avoid a zinc-induced copper deficiency.

1 Star
Goiter
Refer to label instructions
Vitamin A levels are lower in people with goiter than in those without. A combination of vitamin C, vitamin E, and beta-carotene prevented goiter formation in iodine-deficient conditions in some research.

Blood levels of vitamin A are lower in people with goiter than in similar people without goiter.122 , 123 The same relationship has been found for vitamin E and goiter.124 Animal research has found that, in iodine-deficient conditions, a supplement combination of vitamin C , vitamin E, and beta-carotene prevented goiter formation (though hypothyroidism was not improved), and vitamin E alone had a similar effect.125 No studies have been done to investigate this benefit in humans.

1 Star
HIV and AIDS Support
Refer to label instructions
Vitamin A deficiency is common in people with HIV infection, and low levels of the vitamin are associated with greater disease severity. Ask your doctor if vitamin A is right for you.

Vitamin A deficiency appears to be very common in people with HIV infection. Low blood levels of vitamin A are associated with greater disease severity126 and increased transmission of the virus from a pregnant mother to her infant.127 However, in preliminary 128 and double-blind129 , 130 trials, supplementation with vitamin A failed to reduce the overall mother-to-child transmission of HIV. HIV-positive women who took 5,000 IU per day of vitamin A (as retinyl palmitate) and 50,000 IU per day of beta-carotene during the third trimester (13 weeks) of pregnancy, plus an additional single amount of 200,000 IU of vitamin A at delivery, had the same rate of transmission of HIV to their infants as those who did not take the supplement. However, lower rates of illness have been observed in the children of HIV-positive mothers when the children were supplemented with 50,000–200,000 IU of vitamin A every two to three months.131

Little research has explored whether vitamin A supplements are helpful at halting disease progression. HIV-positive children given two consecutive oral supplements of vitamin A (200,000 IU in a gelcap) in the two days following influenza vaccinations had a modest but significant decrease in viral load.132 In one trial, giving people an extremely high (300,000 IU) amount of vitamin A one time only did not improve short-term measures of immunity in women with HIV.133

1 Star
Hypothyroidism
Refer to label instructions
People with hypothyroidism may have an impaired ability to convert beta-carotene to vitamin A. For this reason, some doctors suggest supplementing with vitamin A.

People with hypothyroidism have been shown to have an impaired ability to convert beta-carotene to vitamin A .134 , 135 For this reason, some doctors suggest taking supplemental vitamin A (approximately 5,000–10,000 IU per day) if they are not consuming adequate amounts in their diet.

1 Star
Pre- and Post-Surgery Health
Refer to label instructions
Topical vitamin A may help speed wound healing and reduce scarring in patients taking corticosteroids, which typically slow wound healing.

Vitamin A plays an important role in wound healing ,136 and one animal study suggests that vitamin A deficiency might contribute to poor recovery after surgery.137 Vitamin A may be particularly beneficial to post-surgical patients who are using corticosteroid medications. These medications typically slow wound healing, and a number of animal studies have found that both topical and oral vitamin A reverse this effect; however, vitamin A does not change healing time in animals not given corticosteroids.138 , 139 , 140 Similar results have been reported for topical vitamin A in some human cases, and these researchers suggest a topical preparation containing 200,000 IU of vitamin A per ounce for improved surgical wound healing in patients using corticosteroids after surgery.141 Topical vitamin A may also reduce scarring in patients taking corticosteroids.142

1 Star
Premenstrual Syndrome
Refer to label instructions
Very high amounts of vitamin A have reduced PMS symptoms in some studies.

Very high amounts of vitamin A—100,000 IU per day or more—have reduced symptoms of PMS,143 , 144 but such an amount can cause serious side effects with long-term use. Women who are or who could become pregnant should not supplement with more than 10,000 IU (3,000 mcg) per day of vitamin A. Other people should not take more than 25,000 IU per day without the supervision of their doctor. As yet, no trials have explored the effects of these safer amounts of vitamin A in women suffering from PMS.

1 Star
Sickle Cell Anemia
Refer to label instructions
Sickle cell anemia patients tend to have low levels of antioxidants, which protect cells from oxygen-related damage. Supplementing with vitamin A may help correct a deficiency.

Antioxidant nutrients protect the body’s cells from oxygen-related damage. Many studies show that sickle cell anemia patients tend to have low blood levels of antioxidants, including carotenoids , vitamin A , vitamin E , and vitamin C , despite adequate intake.145 , 146 , 147 , 148 , 149 , 150 Low blood levels of vitamin E in particular have been associated with higher numbers of diseased cells in children151 and with greater frequency of symptoms in adults.152 A small, preliminary trial reported a 44% decrease in the average number of diseased cells in six sickle cell anemia patients given 450 IU vitamin E per day for up to 35 weeks. This effect was maintained as long as supplementation continued.153

1 Star
Type 1 Diabetes (Selenium, Vitamin C, Vitamin E)
Refer to label instructions
A combination of the antioxidants selenium, vitamin A, vitamin C, and vitamin E has been shown to improve diabetic retinopathy.
Because oxidation damage is believed to play a role in the development of diabetic eye damage ( retinopathy ), antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium , 800 IU vitamin E , 10,000 IU vitamin A , and 1,000 mg vitamin C for several years to 20 people with diabetic eye damage ( retinopathy ). During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.154 People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.
1 Star
Type 1 Diabetes and Diabetic Retinopathy (Selenium, Vitamin C, Vitamin E)
Refer to label instructions
Antioxidant nutrients including selenium, vitamin A, vitamin C, and vitamin E may combat free radicals associated with diabetic retinopathy.
Because oxidation damage is believed to play a role in the development of diabetic eye damage ( retinopathy ), antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium , 800 IU vitamin E , 10,000 IU vitamin A , and 1,000 mg vitamin C for several years to 20 people with diabetic eye damage ( retinopathy ). During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.155 People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.
1 Star
Urinary Tract Infection
Refer to label instructions
Vitamin A deficiency increases the risk of many infection, supplementing with it may restore levels and help support the immune system.

Vitamin A deficiency increases the risk of many infections. Although much of the promising research with vitamin A supplements and infections has focused on measles,156 vitamin A is also thought to be helpful in other infections. Some doctors recommend that people with urinary tract infections take vitamin A. A typical amount recommended to correct a deficiency is 10,000 to 25,000 IU per day.

1 Star
Vaginitis
Refer to label instructions
Some doctors recommend vaginal administration of vitamin A to improve the integrity of the vaginal tissue and to enhance the function of local immune cells.

Some doctors recommend vitamin E (taken orally, topically, or vaginally) for certain types of vaginitis. Vitamin E as a suppository in the vagina or vitamin E oil can be used once or twice per day for 3 to 14 days to soothe the mucous membranes of the vagina and vulva. Some doctors recommend vaginal administration of vitamin A to improve the integrity of the vaginal tissue and to enhance the function of local immune cells. Vitamin A can be administered vaginally by inserting a vitamin A capsule or using a prepared vitamin A suppository. Vitamin A used this way can be irritating to local tissue, so it should not be used more than once per day for up to seven consecutive days.

How It Works

How to Use It

For most people, up to 25,000 IU (7,500 mcg) of vitamin A per day is considered safe. However, people over age 65 and those with liver disease should probably not supplement with more than 15,000 IU per day, unless supervised by a doctor. In women who could become pregnant , the maximum safe intake is being re-evaluated. However, less than 10,000 IU (3,000 mcg) per day is generally accepted as safe. There is concern that larger intakes could cause birth defects . Whether the average person would benefit from vitamin A supplementation remains unclear.

Where to Find It

Liver, dairy products, and cod liver oil are good sources of vitamin A. Vitamin A is also available in supplement form.

Possible Deficiencies

People who limit their consumption of liver, dairy foods, and beta-carotene -containing vegetables can develop a vitamin A deficiency. Extremely low birth weight babies (2.2 pounds or less) are at high risk of being born with a deficiency, and vitamin A shots given to these infants have been reported in double-blind research to reduce the risk of lung disease.157 The earliest deficiency sign is poor night vision . Deficiency symptoms can also include dry skin, increased risk of infections , and metaplasia (a precancerous condition). Severe deficiencies causing blindness are extremely rare in Western societies.

Less severe deficiencies are more likely to occur with a variety of conditions causing malabsorption . A high incidence of vitamin A deficiency in people infected with HIV has also been reported. People with hypothyroidism have an impaired ability to convert beta-carotene to vitamin A.158 , 159 For this reason, some doctors suggest taking supplemental vitamin A (perhaps 5,000–10,000 IU per day) if they are not consuming adequate amounts in their diet.

Very old people with type 2 diabetes have shown a significant age-related decline in blood levels of vitamin A, irrespective of their dietary intake.160

Interactions

Interactions with Supplements, Foods, & Other Compounds

Taking vitamin A and iron together helps overcome iron deficiency more effectively than iron supplementation alone.161 Supplementation with zinc , iron, or the combination has been found to improve vitamin A status among children at high risk for deficiency of the three nutrients.162

Interactions with Medicines

Certain medicines interact with this supplement.

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

  • Carbamazepine

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.169 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

  • Cholestyramine

    Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , and K .188 , 189 Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.190 Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.191

  • Colesevelam

    Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , and K .198 , 199 Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.200 Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.201

  • Colestipol

    Bile acid sequestrants, including colestipol, may prevent absorption of folic acid and the fat-soluble vitamins A , D , E , K .202 , 203 People taking colestipol should consult with their doctor about vitamin malabsorption and supplementation. People should take other drugs and vitamin supplements one hour before or four to six hours after colestipol to improve absorption.204

    Animal studies suggest calcium and zinc may be depleted by taking cholestyramine, another bile acid sequestrant. 205 Whether these same interactions would occur with colestipol is not known.

  • Felbamate

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.219 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

  • Gabapentin

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.232 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Levetiracetam

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.245 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

  • Mineral Oil

    Mineral oil has interfered with the absorption of many nutrients, including beta-carotene , calcium , phosphorus , potassium , and vitamins A , D , K , and E in some,270 but not all,271 research. Taking mineral oil on an empty stomach may reduce this interference. It makes sense to take a daily multivitamin-mineral supplement two hours before or after mineral oil. It is important to read labels, because many multivitamins do not contain vitamin K or contain inadequate (less than 100 mcg per day) amounts.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Neomycin

    Neomycin can decrease absorption or increase elimination of many nutrients, including calcium , carbohydrates, beta-carotene , fats, folic acid , iron , magnesium , potassium , sodium, and vitamin A , vitamin B12 , vitamin D , and vitamin K .272 , 273 Surgery preparation with oral neomycin is unlikely to lead to deficiencies. It makes sense for people taking neomycin for more than a few days to also take a multivitamin-mineral supplement.

  • Orlistat

    In one well-controlled study, taking orlistat for six months resulted in reduced blood levels of vitamins A and D, though levels for most individuals remained within the normal range. However, a few people developed levels low enough to require supplementation.274 Other studies have shown that taking orlistat had no affect on blood vitamin A levels.275 , 276 Although additional research is needed, the current evidence suggests that individuals taking orlistat for more than six months should supplement with vitamins A and D.

  • Oxcarbazepine

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.277 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

  • Phenobarbital

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.278 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Phenytoin

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.279 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

  • Thioridazine

    A review of people taking thioridazine showed that they had higher blood levels of vitamin A than did individuals not using the drug.295 More research is necessary to determine whether taking vitamin A supplements with thioridazine might cause dangerously high vitamin A levels. Until more is known, people taking thioridazine should exercise caution with vitamin A supplementation and be alert for side effects such as bone pain, headaches, dry scaly skin, and hair loss.

  • Topiramate

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.302 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

  • Valproate

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.309 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Zonisamide

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.316 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

Reduce Side Effects

  • Busulfan

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.163 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.164 Vitamin C appears to increase the effectiveness of chemotherapy in animals165 and with human breast cancer cells in test tube research.166 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.167

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.168 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Carboplatin

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.170 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.171 Vitamin C appears to increase the effectiveness of chemotherapy in animals172 and with human breast cancer cells in test tube research.173 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.174

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.175 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

  • Carmustine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.176 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.177 Vitamin C appears to increase the effectiveness of chemotherapy in animals178 and with human breast cancer cells in test tube research.179 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.180

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.181 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Chlorambucil

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.182 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.183 Vitamin C appears to increase the effectiveness of chemotherapy in animals184 and with human breast cancer cells in test tube research.185 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.186

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.187 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Cladribine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.192 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.193 Vitamin C appears to increase the effectiveness of chemotherapy in animals194 and with human breast cancer cells in test tube research.195 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.196

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.197 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Erlotinib

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.213 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.214 Vitamin C appears to increase the effectiveness of chemotherapy in animals215 and with human breast cancer cells in test tube research.216 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.217

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.218 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Floxuridine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.220 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.221 Vitamin C appears to increase the effectiveness of chemotherapy in animals222 and with human breast cancer cells in test tube research.223 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.224

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.225 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Fludarabine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.226 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.227 Vitamin C appears to increase the effectiveness of chemotherapy in animals228 and with human breast cancer cells in test tube research.229 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.230

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.231 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Ifosfamide

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.233 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.234 Vitamin C appears to increase the effectiveness of chemotherapy in animals235 and with human breast cancer cells in test tube research.236 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.237

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.238 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Irinotecan

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.239 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.240 Vitamin C appears to increase the effectiveness of chemotherapy in animals241 and with human breast cancer cells in test tube research.242 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.243

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.244 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Lomustine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.246 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.247 Vitamin C appears to increase the effectiveness of chemotherapy in animals248 and with human breast cancer cells in test tube research.249 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.250

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.251 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Mechlorethamine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.252 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.253 Vitamin C appears to increase the effectiveness of chemotherapy in animals254 and with human breast cancer cells in test tube research.255 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.256

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.257 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Melphalan

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.258 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.259 Vitamin C appears to increase the effectiveness of chemotherapy in animals260 and with human breast cancer cells in test tube research.261 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.262

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.263 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

  • Mercaptopurine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.264 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.265 Vitamin C appears to increase the effectiveness of chemotherapy in animals266 and with human breast cancer cells in test tube research.267 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.268

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.269 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Polifeprosan 20 with Carmustine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.280 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.281 Vitamin C appears to increase the effectiveness of chemotherapy in animals282 and with human breast cancer cells in test tube research.283 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.284

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.285 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Prednisolone

    In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.286 In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

    Although blood levels of vitamin A appear to increase during dexamethasone therapy287—most likely due to mobilization of the vitamin from its stores in the liver evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.288

  • Thioguanine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.289 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.290 Vitamin C appears to increase the effectiveness of chemotherapy in animals291 and with human breast cancer cells in test tube research.292 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.293

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.294 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Thiotepa

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.296 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.297 Vitamin C appears to increase the effectiveness of chemotherapy in animals298 and with human breast cancer cells in test tube research.299 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.300

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.301 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Uracil Mustard

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.303 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.304 Vitamin C appears to increase the effectiveness of chemotherapy in animals305 and with human breast cancer cells in test tube research.306 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.307

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.308 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Vincristine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.310 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.311 Vitamin C appears to increase the effectiveness of chemotherapy in animals312 and with human breast cancer cells in test tube research.313 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.314

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.315 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Support Medicine

  • Docetaxel

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.206 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.207 Vitamin C appears to increase the effectiveness of chemotherapy in animals208 and with human breast cancer cells in test tube research.209 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.210

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but it clearly shows that antioxidants need not be avoided for fear that the actions of chemotherapy are interfered with.211 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    A new formulation of selenium (Seleno-Kappacarrageenan) was found to reduce kidney damage and white blood cell–lowering effects of cisplatin in one human study. However, the level used in this study (4,000 mcg per day) is potentially toxic and should only be used under the supervision of a doctor.212

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Reduces Effectiveness

  • none

Potential Negative Interaction

  • Atorvastatin

    A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found blood vitamin A levels increased over two years of therapy.317 Until more is known, people taking HMG-CoA reductase inhibitors, including atorvastatin, should have blood levels of vitamin A monitored if they intend to supplement vitamin A.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Isotretinoin

    Although little is known about how isotretinoin interacts with real vitamin A, the two are structurally similar and have similar toxicities. Therefore, people taking isotretinoin should avoid vitamin A supplements at levels higher than typically found in a multivitamin (10,000 IU per day).

  • Minocycline

    A 16-year-old girl developed headaches and double vision following treatment for acne with vitamin A and minocycline. These side effects disappeared once the compounds were discontinued.318 More research is needed to determine whether the symptoms could have been caused by an interaction between vitamin A and the drug.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Tretinoin

    Large amounts of vitamin A can cause side effects, and oral tretinoin can cause similar side effects. Combining vitamin A with oral tretinoin is likely to increase the risk of side effects. People taking oral tretinoin should probably not take more than 10,000 IU of supplemental vitamin A per day.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Explanation Required

  • Busulfan

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.319 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Capecitabine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.326 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Carboplatin

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.327 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Carmustine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.328 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Chlorambucil

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.329 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Cisplatin

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.330 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.331 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.332 Vitamin C appears to increase the effectiveness of chemotherapy in animals333 and with human breast cancer cells in test tube research.334 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.335

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.336 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Cladribine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.337 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Cortisone

    In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.338 In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

    Although blood levels of vitamin A appear to increase during dexamethasone therapy339—most likely due to mobilization of the vitamin from its stores in the liver—evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.340

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Cyclophosphamide

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.341 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Cytarabine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.343 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.344 Vitamin C appears to increase the effectiveness of chemotherapy in animals345 and with human breast cancer cells in test tube research.346 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.347

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.348 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Desogestrel-Ethinyl Estradiol

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.349 , 350 , 351 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .352 , 353 , 354 Oral contraceptives may interfere with manganese absorption.355 The clinical importance of these actions remains unclear.

  • Dexamethasone

    In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.356 In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

    Although blood levels of vitamin A appear to increase during dexamethasone therapy357—most likely due to mobilization of the vitamin from its stores in the liver—evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.358

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Docetaxel

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.359 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Erlotinib

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.360 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Ethinyl Estradiol and Levonorgestrel
    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.361 , 362 , 363 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .364 , 365 , 366 Oral contraceptives may interfere with manganese absorption.367 The clinical importance of these actions remains unclear.
  • Ethinyl Estradiol and Norethindrone

    A review of literature suggests that women who use OCs may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.368 , 369 , 370 OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .371 , 372 , 373 OCs may interfere with manganese absorption.374 The clinical importance of these actions remains unclear.

  • Ethinyl Estradiol and Norgestrel

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.375 , 376 , 377 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .378 , 379 , 380 Oral contraceptives may interfere with manganese absorption.381 The clinical importance of these actions remains unclear.

  • Etoposide

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.383 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.384 Vitamin C appears to increase the effectiveness of chemotherapy in animals385 and with human breast cancer cells in test tube research.386 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.387

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.388 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Floxuridine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.389 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Fludarabine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.390 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Fluorouracil

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.392 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.393 Vitamin C appears to increase the effectiveness of chemotherapy in animals394 and with human breast cancer cells in test tube research.395 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.396

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but the article strongly suggests that antioxidants need not be avoided for fear that the actions of chemotherapy would be interfered with.397

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Fluvastatin

    A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found blood vitamin A levels increased during two years of therapy.398 Until more is known, people taking HMG-CoA reductase inhibitors, including fluvastatin, should have blood levels of vitamin A monitored if they intend to supplement vitamin A.

  • Hydroxyurea

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.400 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.401 Vitamin C appears to increase the effectiveness of chemotherapy in animals402 and with human breast cancer cells in test tube research.403 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.404

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.405 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Ifosfamide

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.406 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Irinotecan

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.407 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Levonorgestrel

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.408 , 409 , 410 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .411 , 412 , 413 Oral contraceptives may interfere with manganese absorption.414 The clinical importance of these actions remains unclear.

  • Levonorgestrel-Ethinyl Estrad

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.415 , 416 , 417 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .418 , 419 , 420 Oral contraceptives may interfere with manganese absorption.421 The clinical importance of these actions remains unclear.

  • Lomustine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.422 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Lovastatin

    A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found serum vitamin A levels increased over two years of therapy.423 It remains unclear whether this moderate increase should suggest that people taking lovastatin have a particular need to restrict vitamin A supplementation.

  • Mechlorethamine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.424 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Medroxyprogesterone

    In a one-year study of predominantly malnourished women in India and Thailand, medroxyprogesterone used for contraception was associated with increased blood levels of vitamin A and folic acid.425 The clinical meaning of these changes remains unclear.

  • Melphalan

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.426 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Mercaptopurine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.427 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Mestranol and Norethindrone

    A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.428 , 429 , 430 Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .431 , 432 , 433 Oral contraceptives may interfere with manganese absorption.434 The clinical importance of these actions remains unclear.

  • Methylprednisolone

    In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.435 In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

    Although blood levels of vitamin A appear to increase during dexamethasone therapy436—most likely due to mobilization of the vitamin from its stores in the liver—evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.437

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Norgestimate-Ethinyl Estradiol

    A review of literature suggests that women who use OCs may experience decreased vitamin B1 , B2 , B3 , B12 , C , and zinc levels.438 , 439 , 440 OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A .441 , 442 , 443 OCs may interfere with manganese absorption.444 The clinical importance of these actions remains unclear.

  • Paclitaxel

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.445 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.446 Vitamin C appears to increase the effectiveness of chemotherapy in animals447 and with human breast cancer cells in test tube research.448 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.449

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but the article strongly suggests that antioxidants need not be avoided for fear that the actions of chemotherapy would be interfered with.450

    A new formulation of selenium (Seleno-Kappacarrageenan) was found to reduce kidney damage and white blood cell–lowering effects of cisplatin in one human study. However, the level used in this study (4,000 mcg per day) is potentially toxic and should only be used under the supervision of a doctor.451

    Glutathione , the main antioxidant found within cells, is frequently depleted in individuals on chemotherapy and/or radiation. Preliminary studies have found that intravenously injected glutathione may decrease some of the adverse effects of chemotherapy and radiation, such as diarrhea .452

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Polifeprosan 20 with Carmustine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.453 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Pravastatin

    A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found serum vitamin A levels increased over two years of therapy.454 It remains unclear whether this moderate increase suggests that people taking lovastatin have a particular need to restrict vitamin A supplementation.

  • Prednisolone

    In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.455 In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

    Although blood levels of vitamin A appear to increase during dexamethasone therapy456—most likely due to mobilization of the vitamin from its stores in the liver evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.457

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Prednisone

    In some people, treatment with corticosteroids can impair wound healing . In one study, topical or internal vitamin A improved wound healing in eight of ten patients on corticosteroid therapy.458 In theory, vitamin A might also reverse some of the beneficial effects of corticosteroids, but this idea has not been investigated and no reports exist of such an interaction in people taking both vitamin A and corticosteroids. People using oral corticosteroids should consult with a doctor to determine whether improved wound healing might outweigh the theoretical risk associated with concomitant vitamin A use.

    Although blood levels of vitamin A appear to increase during dexamethasone therapy459—most likely due to mobilization of the vitamin from its stores in the liver—evidence from animal studies has also indicated that corticosteroids can deplete vitamin A from tissues.460

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Primidone

    Anticonvulsant drugs can occasionally cause birth defects when taken by pregnant women, and their toxicity might be related to low blood levels of vitamin A. One controlled study showed that taking multiple anticonvulsant drugs results in dramatic changes in the way the body utilizes vitamin A.461 Further controlled research is needed to determine whether supplemental vitamin A might prevent birth defects in children born to women on multiple anticonvulsant therapy. Other research suggests that ingestion of large amounts of vitamin A may promote the development of birth defects, although the studies are conflicting.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Simvastatin

    A study of 37 people with high cholesterol treated with diet and HMG-CoA reductase inhibitors found blood vitamin A levels increased over two years of therapy.462 Until more is known, people taking HMG-CoA reductase inhibitors, including simvastatin, should have blood levels of vitamin A monitored if they intend to supplement vitamin A.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Thioguanine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.463 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Thiotepa

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.464 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Uracil Mustard

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.465 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

  • Vinblastine

    Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.467 However, most scientific research does not support this supposition.

    A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.468 Vitamin C appears to increase the effectiveness of chemotherapy in animals469 and with human breast cancer cells in test tube research.470 In a double-blind study, Japanese researchers found that the combination of vitamin E , vitamin C, and N-acetyl cysteine (NAC) —all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.471

    A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but neither does it show that antioxidants should be avoided for fear that the actions of chemotherapy are interfered with.472 Although research remains incomplete, the idea that people taking chemotherapy should avoid antioxidants is not supported by scientific research.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • Vincristine

    A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.473 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Side Effects

Since a 1995 report from the New England Journal of Medicine, 474 women who are or could become pregnant have been told by doctors to take less than 10,000 IU (3,000 mcg) per day of vitamin A to avoid the risk of birth defect . A recent report studied several hundred women exposed to 10,000–300,000 IU (median exposure of 50,000 IU) per day.475 Three major malformations occurred in this study, but all could have happened in the absence of vitamin A supplementation. Surprisingly, no congenital malformations happened in any of the 120 infants exposed to maternal intakes of vitamin A that exceeded 50,000 IU per day. In fact, the high-exposure group had a 50% decreased risk for malformations compared with infants not exposed to vitamin A. The authors noted that some previous studies found no link between vitamin A and birth defects, and argued the studies that did find such a link suffered from various weaknesses. A closer look at the recent study reveals a 32% higher than expected risk of birth defects in infants exposed to 10,000–40,000 IU of vitamin A per day, but paradoxically a 37% decreased risk for those exposed to even higher levels. This suggests that both “higher” and “lower” risks may have been due to chance.

Excessive dietary intake of vitamin A has been associated with birth defects in humans in fewer than 20 reported cases over the past 30 years.476 , 477 Presently, the level at which vitamin A supplementation may cause birth defects is not known, though combined human and animal data suggest that 30,000 IU per day should be considered safe.478 Women who are or who could become pregnant should consult with a doctor before supplementing with more than 10,000 IU per day.

Vitamin A supplements can both help and hurt children. Many people have heard that vitamin A supplements support immune function and prevent infections . This is true under some circumstances. However, vitamin A can also increase the risk of infections, according to the findings of a double-blind trial.479 In a study of African children between six months and five years old, a 44% reduction in the risk of severe diarrhea was seen in those children given four 100,000–200,000 IU applications of vitamin A (the lower amount for those less than a year old) during an eight-month period. On further investigation, the researchers discovered that the reduction in diarrhea occurred only in children who were very malnourished. For children who were not starving, vitamin A supplementation actually increased the risk of diarrhea compared with the placebo group. The vitamin A-supplemented children also had a 67% increased risk of coughing and rapid breathing, signs of further lung infection, although this problem did not appear in children infected with AIDS. These findings should be of concern to American parents, whose children are not usually infected with AIDS or severely malnourished. Such relatively healthy children fared poorly in the African trial in terms of both the risk of diarrhea and the risk of continued lung problems. Vitamin A provided no benefit to the well-nourished kids. Therefore, it makes sense to not give vitamin A supplements to children unless there is a special reason to do so, such as the presence of a condition causing malabsorption (e.g., celiac disease ).

In a study of people with retinitis pigmentosa (a degenerative condition of the eye), participants received 15,000 IU of vitamin A per day for 12 years with no signs of adverse effects or toxicity.480 For other adults, intake above 25,000 IU (7,500 mcg) per day can—in rare cases—cause headaches, dry skin, hair loss, fatigue, bone problems, and liver damage.481 At higher levels (for example 100,000 IU per day) these problems become more common.

A controlled clinical trial showed that people who took 25,000 IU of vitamin A per day for a median of 3.8 years had an 11% increase in triglycerides , a 3% increase in total cholesterol and a 1% decrease in HDL cholesterol compared to those who did not take vitamin A.482 Although the significance of these findings is not clear, people at risk for cardiovascular disease should use caution when considering long-term vitamin A supplementation.

One study found that increasing the intake of vitamin A in the diet was associated with bone loss and risk of hip fracture, possibly due to a vitamin A-induced stimulation of cells that break down bone.483 In this study, a vitamin A intake greater than 5,000 IU per day, when compared to a lower intake, was associated with a reduction in bone mineral density that approximately doubles the risk of hip fracture. Beta-carotene (which can be used by the body to make vitamin A) has not been linked to reduced bone mass. Until more is known, people concerned about osteoporosis may consider taking beta-carotene supplements rather than supplementing with vitamin A.

Data from test tube, animal, and human studies show that excessive vitamin A intake can accelerate bone loss and inhibit formation of new bone, increasing the risk of osteoporosis.484 In humans, small studies have found these effects at about 85,000–125,000 IU per day. 485 , 486

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242. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

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247. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409-15.

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249. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

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255. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

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322. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575-9.

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327. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

328. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

329. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

330. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

331. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823-32.

332. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409-15.

333. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575-9.

334. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

335. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353-9.

336. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209-40 [review].

337. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

338. Hunt TK, Ehrlich HP, Garcia JA, et al. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633-41.

339. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547-53.

340. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376-82.

341. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

342. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

343. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823-32.

344. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409-15.

345. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575-9.

346. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

347. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353-9.

348. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209-40 [review].

349. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

350. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

351. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.

352. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

353. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

354. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711-5.

355. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

356. Hunt TK, Ehrlich HP, Garcia JA, et al. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633-41.

357. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547-53.

358. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376-82.

359. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

360. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

361. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

362. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

363. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.

364. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

365. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

366. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711-5.

367. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

368. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

369. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

370. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.

371. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

372. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

373. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711-5.

374. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

375. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

376. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

377. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.

378. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

379. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

380. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711-5.

381. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

382. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

383. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823-32.

384. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409-15.

385. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575-9.

386. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

387. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353-9.

388. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209-40 [review].

389. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

390. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

391. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

392. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823-32.

393. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409-15.

394. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575-9.

395. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

396. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353-9.

397. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209-40 [review].

398. Muggeo M, Zenti MG, Travia D, et al. Serum retinol levels throughout 2 years of cholesterol-lowering therapy. Metabolism 1995;44:398-403.

399. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

400. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823-32.

401. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409-15.

402. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575-9.

403. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

404. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353-9.

405. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209-40 [review].

406. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

407. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

408. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

409. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

410. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.

411. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

412. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

413. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711-5.

414. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

415. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

416. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

417. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.

418. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

419. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

420. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711-5.

421. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

422. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

423. Muggeo M, Zenti MG, Travia D, et al. Serum retinol levels throughout 2 years of cholesterol-lowering therapy. Metabolism 1995;44:398-403.

424. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

425. Joshi UM, Virkar KD, Amatayakul K, et al. Impact of hormonal contraceptives vis-a-vis non-hormonal factors on the vitamin status of malnourished women in India and Thailand. World Health Organization: Special Programme of Research, Development and Research Training in Human Reproduction. Task Force on Oral Contraceptives. Hum Nutr Clin Nutr 1986;40:205-20.

426. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

427. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

428. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

429. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

430. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.

431. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

432. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

433. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711-5.

434. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

435. Hunt TK, Ehrlich HP, Garcia JA, et al. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633-41.

436. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547-53.

437. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376-82.

438. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

439. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

440. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.

441. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].

442. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.

443. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711-5.

444. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

445. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823-32.

446. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409-15.

447. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575-9.

448. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

449. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353-9.

450. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209-40 [review].

451. Hu Y-J, Chen Y, Zhang Y-Q, et al. The protective role of selenium on the toxicity of cisplatin-contained chemotherapy regimen in cancer patients. Biol Trace Elem Res 1997;56:331-41.

452. De Maria D, Falchi AM, Venturino P. Adjuvant radiotherapy of the pelvis with or without reduced glutathione: a randomized trial in patients operated on for endometrial cancer. Tumori 1992;78:374-6.

453. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

454. Muggeo M, Zenti MG, Travia D, et al. Serum retinol levels throughout 2 years of cholesterol-lowering therapy. Metabolism 1995;44:398-403.

455. Hunt TK, Ehrlich HP, Garcia JA, et al. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633-41.

456. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547-53.

457. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376-82.

458. Hunt TK, Ehrlich HP, Garcia JA, et al. Effect of vitamin A on reversing the inhibitory effect of cortisone on healing of open wounds in animals and man. Ann Surg 1969;170:633-41.

459. Shenai JP, Mellen BG, Chytil F. Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia. Pediatrics 2000;106:547-53.

460. Georgieff MK, Radmer WJ, Sowell AL. The effect of glucocorticosteroids on serum, liver, and lung vitamin A and retinyl ester concentrations. J Pediatr Gastroenterol Nutr 1991;13:376-82.

461. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogensis of anticonvulsant therapy. Life Sci 1995;57:53-60.

462. Muggeo M, Zenti MG, Travia D, et al. Serum retinol levels throughout 2 years of cholesterol-lowering therapy. Metabolism 1995;44:398-403.

463. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

464. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

465. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

466. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

467. Witenberg B, Kalir HH, Raviv Z, et al. Inhibition by ascorbic acid of apoptosis induced by oxidative stress in HL-60 myeloid leukemia cells. Biochem Pharmacol 1999;57:823-32.

468. Sacks PG, Harris D, Chou T-C. Modulation of growth and proliferation in squamous cell carcinoma by retinoic acid: A rationale for combination therapy with chemotherapeutic agents. Int J Cancer 1995;61:409-15.

469. Taper HS et al. Non-toxic potentiation of cancer chemotherapy by combined C and K3 vitamin pre-treatment. Int J Cancer 1987;40:575-9.

470. Kurbacher CM, Wagner U, Kolster B, et al. Ascorbic acid (vitamin C) improves the antineoplastic activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. Cancer Letters 1996:103-19.

471. Wagdi P, Fluri M, Aeschbacher B, et al. Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. Jpn Heart J 1996;37:353-9.

472. Weijl NI, Cleton FJ, Osanto S. Free radicals and antioxidants in chemotherapy-induced toxicity. Cancer Treatment Rev 1997;23:209-40 [review].

473. Israel L, Hajji O, Grefft-Alami A, et al. Augmentation par la vitamine A des effets de la chimiotherapie dans les cancers du sein metastases apres la menopause. Ann Med Interne 1985;136:551-4.

474. Rothman KJ, Moore LL, Singer MR, et al. Teratogenicity of high vitamin A intake. N Engl J Med 1995;333:1369-73.

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