|CRDAMC Homepage | CRDAMC Library Phone #: (254) 288-8366 | CRDAMC Library Fax #: (254) 288-8368|
Vitamin A is a fat-soluble antioxidant that protects your cells against damaging free radicals and plays other vital roles in the body. However, it is potentially more dangerous than most other vitamins because it can build up to toxic levels. For this reason, it should be used with caution.
It has long been assumed that beta-carotene supplements taken at nutritional doses are a safer way to get the vitamin A you need. However, while this may be true in general, beta-carotene also appears to present some risks. See the full Beta-Carotene article for more information.
Vitamin A is an essential nutrient—meaning you must get it in the diet. The official U.S. recommendations for daily intake of vitamin A 38 are expressed in international units (IUs) or retinol activity equivalents (RAE), which are measured in micrograms, as follows:
Warning : Pregnant women should not take vitamin A supplements. Instead they should take beta-carotene.
We get vitamin A from many foods, in the form of either vitamin A or beta-carotene. Liver and dairy products are excellent sources of vitamin A. Carrots, apricots, collard greens, kale, sweet potatoes, parsley, and spinach are good sources as well.
Deficiency in vitamin A is common in developing countries.1 In the developed world, deficiency is relatively rare. However, certain diseases can cause vitamin A deficiency by impairing the ability of the digestive tract to absorb nutrients. These include Crohn’s disease, ulcerative colitis, and cystic fibrosis.
Therapeutic Dosages TOP
Although some studies have used high doses of vitamin A, intake above the safe upper limit level is not recommended except on physician advice (see Safety Issues).
Therapeutic Uses TOP
There is some evidence that vitamin A supplements reduce deaths from measles and other infectious illnesses among children in developing countries,3,39 presumably because they correct a deficiency in the children's diets. This doesn't mean that vitamin A supplements above and beyond the basic nutritional requirement are a useful treatment for measles or any other childhood disease.
Vitamin A might improve blood sugar control in people with diabetes. Unfortunately, people with diabetes may also be especially vulnerable to liver damage from excessive amounts of vitamin A (see Safety Issues). Therefore, if you have diabetes, you should take vitamin A only on the advice of a physician.
Vitamin A has shown some potential for preventing one type of skin cancer (squamous cell cancer).41,42 However, in these studies, doses above the standard safe upper limits have been used. With proper monitoring, this may be safe, but we do not recommend trying it without physician supervision. High-dose vitamin A has been tried for a variety of other skin diseases, including acne, psoriasis, rosacea, seborrhea, and eczema,21-24 as well as menorrhagia (heavy menstruation)4 and retinitis pigmentosa (a chronic disease of the eyes).43-44 However, the benefits seen have been modest at best, and again the recommended dosages of vitamin A are so high as to raise concerns about toxic risk.
Vitamin A might be beneficial for people with HIV; however, results of studies have been contradictory, and some evidence even suggests that vitamin A supplements might increase transmission of the disease from a pregnant mother to her newborn.45
Topical vitamin A may be helpful for treatment of aging skin. One double-blind, placebo-controlled study found that a 0.4% vitamin A lotion applied three times a week significantly reduced the number of “fine” wrinkles in seniors.46 Benefits were also seen in terms of some biochemical measures of skin health.
On the basis of very weak evidence, too weak to be relied upon at all, vitamin A has been proposed as a treatment for a wide variety of other conditions, including Down's syndrome, ear infections, eating disorders, glaucoma, gout, impaired night vision, kidney stones, lupus, multiple sclerosis, ulcerative colitis, and ulcers.
What Is the Scientific Evidence for Vitamin A? TOP
An observational study suggests that vitamin A supplements may improve blood sugar control in people with diabetes.20 However, due to safety concerns, they should not supplement with vitamin A except under medical supervision (see Safety Issues).
Menorrhagia (Heavy Menstruation)
One study suggests that women with heavy menstrual bleeding can benefit from taking 25,000 IU daily of vitamin A.25 But vitamin A cannot be recommended as an ongoing treatment for menorrhagia, since women who menstruate can become pregnant, and even fairly low doses of supplemental vitamin A may cause birth defects.
HIV Support TOP
One small double-blind study suggested that taking beta-carotene might raise white blood cell count in people with HIV.26 However, two subsequent larger controlled trials found no significant differences between those taking beta-carotene or placebo in white blood cell count, CD4+ count, or other measures of immune function.27,28
Two observational studies lasting 6 to 8 years suggest that higher intakes of vitamin A or beta-carotene may be helpful, but they also found that caution is in order with regard to dosage.29,30 This group of researchers generally linked higher intake of vitamin A or beta-carotene to lower risk of AIDS and lower death rates, with an important exception: people with the highest intake of either nutrient (more than 11,179 IU per day of beta-carotene, more than 20,268 IU per day of vitamin A) did worse than those who took somewhat less.
Despite hopes that vitamin A given to pregnant, HIV-positive women might decrease the infection rate of their babies, two double-blind studies have found no significant differences between babies whose mothers took vitamin A compared to those whose mothers took placebo.31,32 In any case, vitamin A is not considered safe in pregnancy; beta-carotene is preferred.
Crohn's Disease TOP
Lower Respiratory Tract Infections TOP
Lower respiratory tract infections include conditions like pneumonia and bronchiolitis. Young children are especially susceptible to these infections. A review of 10 trials involving over 33,000 children under age 7 years found that, in the majority of cases, vitamin A did not reduce the incidence of infection or severity of symptoms.47 In two of the studies, vitamin A was beneficial for undernourished children. However, children with adequate nutrition actually faired worse.
Safety Issues TOP
The safe upper intake levels of vitamin A have been set as follows:38
It is thought that dosages of vitamin A above 50,000 IU per day taken for several years can cause liver injury, bone problems, fatigue, hair loss, headaches, and dry skin. However, one recent study found no harm with dosages as high as 75,000 IU taken for 1 year.42 Nonetheless, we do not recommend using vitamin A at doses over the upper levels, except under close physician supervision. Some people may be more likely to develop toxic symptoms than others.
If you already have liver disease, check with your doctor before taking vitamin A supplements, because even small doses may be harmful.
It is thought that people with diabetes may have trouble releasing vitamin A stored in the liver. This may mean that they are at greater risk for vitamin A toxicity.
Excessive intake of vitamin A (or beta-carotene) appears to accelerate liver injury in people with alcoholism.34 In addition, relatively high intake of vitamin A (but not beta-carotene) has been associated with increased risk of osteoporosis.35,40
Women should avoid supplementing with vitamin A during pregnancy, because at toxic levels it might increase the risk of birth defects. Pregnant women taking valproic acid medications (Depakote, Depacon, or Depakene) may be even more at risk of vitamin A toxicity.36
Interactions You Should Know About TOP
If you are taking:
References[ + ]
1. Combs G. The Vitamins. 2nd ed. New York, NY: Academic Press; 1998:5-6.
2. West RJ, Lloyd JK. The effect of cholestyramine on intestinal absorption. Gut. 1975;16:93-98.
3. Glasziou PP, Mackerras DE. Vitamin A supplementation in infectious diseases: a meta-analysis. BMJ. 1993;306:366-370.
4. Lithgow DM, Politzer WM. Vitamin A in the treatment of menorrhagia. S Afr Med J. 1977;51:191-193.
5. Semba RD, Graham NM, Caiaffa WT, et al. Increased mortality associated with vitamin A deficiency during human immunodeficiency virus type 1 infection. Arch Intern Med. 1993;153:2149-2154.
6. Bianchi-Santamaria A, Fedeli S, Santamaria L. Short communication: possible activity of beta-carotene in patients with the AIDS related complex. A pilot study. Med Oncol Tumor Pharmacother. 1992;9:151-153.
7. Alexander M, Newmark H, Miller RG. Oral beta-carotene can increase the number of OKT4+ cells in human blood. Immunol Lett. 1985;9:221-224.
8. Fryburg DA, Mark RJ, Griffith BP, et al. The effect of supplemental beta-carotene in immunologic indices in patients with AIDS: a pilot study. Yale J Biol Med. 1995;68:19-23.
9. Coodley GO, Nelson HD, Loveless MO, et al. Beta-carotene in HIV infection. J Acquir Immune Defic Syndr Hum Retrovirol. 1993;6:272-276.
10. Coodley GO, Coodley MK, Lusk R, et al. Beta-carotene in HIV infection: an extended evaluation. AIDS. 1996;10:967-973.
11. Constans J, Delmas-Beauvieux MC, Sergeant C, et al. One-year antioxidant supplementation with beta-carotene or selenium for patients infected with human immunodeficiency virus: a pilot study. Clin Infect Dis. 1996;23:654-656.
12. Wright JP, Mee AS, Parfitt A, et al. Vitamin A therapy in patient's with Crohn's disease. Gastroenterology. 1985;88:512-514.
13. Glasziou PP, Mackerras DE. Vitamin A supplementation in infectious diseases: a meta-analysis. BMJ. 1993;306:366-370.
14. Bresee JS, Fischer M, Dowell SF, et al. Vitamin A therapy for children with respiratory syncytial virus infection: a multicenter trial in the United States. Pediatr Infect Dis J. 1996;15:777-782.
15. Neuzil KM, Gruber WC, Chytil F, et al. Safety and pharmacokinetics of vitamin A therapy for infants with respiratory syncytial virus infections. Antimicrob Agents Chemother. 1995;39:1191-1193.
16. Martinoli L, Di Felice M, Seghieri G, et al. Plasma retinol and alpha-tocopherol concentrations in insulin-dependent diabetes mellitus: their relationship to microvascular complications. Int J Vitam Nutr Res. 1993;63:87-92.
17. Singh RB, Niaz MA, Ghosh S, et al. Dietary intake and plasma levels of antioxidant vitamins in health and disease: a hospital-based case-control study. J Nutr Environ Med. 1995;5:235-242.
18. Basualdo CG, Wein EE, Basu TK. Vitamin A (retinol) status of first nation adults with non-insulin-dependent diabetes mellitus. J Am Coll Nutr. 1997;16:39-45.
19. Straub RH, Rokitzki L, Schumacher T, et al. No evidence of deficiency of vitamins A, E, beta-carotene, B1, B2, B6, B12 and folate in neuropathic type II diabetic women. Int J Vitam Nutr Res. 1993;63:239-240.
20. Facchini F, Coulston AM, Reaven GM. Relation between dietary vitamin intake and resistance to insulin-mediated glucose disposal in healthy volunteers. Am J Clin Nutr. 1996;63:946-949.
21. Stoesser AV, Nelson LS. Synthetic vitamin A in the treatment of eczema in children. Ann Allergy. 1952;10:703-704.
22. Kligman AM, Mills OH Jr, Leyden JJ, et al. Oral vitamin A in acne vulgaris. Preliminary report. Int J Dermatol. 1981;20:278-285.
23. Marrakchi S, Kim I, Delaporte E, et al. Vitamin A and E blood levels in erythrodermic and pustular psoriasis associated with chronic alcoholism. Acta Derm Venereol. 1994;74:298-301.
24. Brenner S, Horwitz C. Possible nutrient mediators in psoriasis and seborrheic dermatitis. II. Nutrient mediators: essential fatty acids; vitamins A, E and D; vitamins B1, B2, B6, niacin and biotin; vitamin C; selenium; zinc; iron. World Rev Nutr Diet. 1988;55:165-182.
25. Lithgow DM, Politzer WM. Vitamin A in the treatment of menorrhagia. S Afr Med J. 1977;51:191-193.
26. Coodley GO, Nelson HD, Loveless MO, et al. Beta-carotene in HIV infection. J Acquir Immune Defic Syndr Hum Retrovirol. 1993;6:272-276.
27. Coodley GO, Coodley MK, Lusk R, et al. Beta-carotene in HIV infection: an extended evaluation. AIDS. 1996;10:967-973.
28. Constans J, Delmas-Beauvieux MC, Sergeant C, et al. One-year antioxidant supplementation with beta-carotene or selenium for patients infected with human immunodeficiency virus: a pilot study [letters]. Clin Infect Dis. 1996;23:654-656.
29. Tang AM, Graham NHM, Kirby AJ, et al. Dietary micronutrient intake and risk of progression to acquired immunodeficiency syndrome (AIDS) in human immunodeficiency virus type 1 (HIV-1)-infected homosexual men. Am J Epidemiol. 1993;138:937-951.
30. Tang AM, Graham NM, Saah AJ. Effects of micronutrient intake on survival in human immunodeficiency virus type 1 infection. Am J Epidemiol. 1996;143:1244-1256.
31. Fawzi WW, Msamanga G, Hunter D, et al. Randomized trial of vitamin supplements in relation to vertical transmission of HIV-1 in Tanzania. J Acquir Immune Defic Syndr Hum Retrovirol. 2000;23:246-254.
32. Coutsoudis A, Pillay K, Spooner E, et al. Randomized trial testing the effect of vitamin A supplementation on pregnancy outcomes and early mother-to-child HIV-1 transmission in Durban, South Africa. South African Vitamin A Study Group. AIDS. 1999;13:1517-1524.
33. Wright JP, Mee AS, Parfitt A, et al. Vitamin A therapy in patient's with Crohn's disease. Gastroenterology. 1985;88:512-514.
34. Leo MA, Lieber CS. Alcohol, vitamin A, and beta-carotene: adverse interactions, including hepatotoxicity and carcinogenicity. Am J Clin Nutr. 1999;69:1071-1085.
35. Melhus H, Michaelsson K, Kindmark A, et al. Excessive dietary intake of vitamin A is associated with reduced bone mineral density and increased risk for hip fracture. Ann Intern Med. 1998;129:770-778.
36. Nau H, Tzimas G, Mondry M, et al. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogenesis of anticonvulsant therapy. Life Sci. 1995;57:53-60.
37. Harris JE. Interaction of dietary factors with oral anticoagulants: review and applications. J Am Diet Assoc. 1995;95:580-584.
38. Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press; 2001.
39. D'Souza RM, D'Souza R. Vitamin A for the treatment of children with measles—a systematic review. J Trop Pediatr. 2002;48:323-327.
40. Michaelsson K, Lithell H, Vessby B, et al. Serum retinol levels and the risk of fracture. N Engl J Med. 2003;348:287-294.
41. Moon TE, Levine N, Cartmel B, et al. Effect of retinol in preventing squamous cell skin cancer in moderate-risk subjects: a randomized, double-blind, controlled trial. Southwest Skin Cancer Prevention Study Group. Cancer Epidemiol Biomarkers Prev. 1997;6:949-956.
42. Alberts D, Ranger-Moore J, Einspahr J, et al. Safety and efficacy of dose-intensive oral vitamin A in subjects with sun-damaged skin. Clin Cancer Res. 2004;10:1875-1880.
43. Berson EL, Rosner B, Sandberg MA, et al. A randomized trial of vitamin A and vitamin E supplementation for retinitis pigmentosa. Arch Ophthalmol. 1993;111:761-72
44. Berson EL, Rosner B, Sandberg MA, et al. Clinical trial of docosahexaenoic acid in patients with retinitis pigmentosa receiving vitamin A treatment. Arch Ophthalmol. 2004;122:1297-1305
45. Mehta S, Fawzi W. Effects of Vitamins, Including Vitamin A, on HIV/AIDS Patients. Vitam Horm. 2007;75:355-383.
46. Kafi R, Kwak HS, Schumacher WE, et al. Improvement of naturally aged skin with vitamin a (retinol). Arch Dermatol. 2007;143:606-612.
47. Chen H, Zhuo Q, Wang J, Wu T. Vitamin A for preventing acute lower respiratory tract infections in children up to seven years of age. Cochrane Database Syst Rev. 2011;(1):CD006090.
Last reviewed December 2015 by EBSCO CAM Review Board
Last Updated: 12/15/2015
EBSCO Information Services is fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.
To send comments or feedback to our Editorial Team regarding the content please email us at email@example.com. Our Health Library Support team will respond to your email request within 2 business days.