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Safety Issues
The safe upper intake levels of vitamin A have been set as follows: 1
- Infants
- 0-12 months: 600 mcg RAE or 2,000 IU
- Children
- 1-3 years: 600 mcg RAE or 2,000 IU
- 4-8 years: 900 mcg RAE or 3,000 IU
- Males and Females
- 9-13 years: 1,700 mcg RAE or 5,660 IUs
- 14-18 years: 2,800 mcg RAE or 9,320 IUs
- 19 years and older: 3,000 mcg RAE or 10,000 IU
- Pregnant Women
- 18 years old or younger: 2,800 mcg RAE or 9,320 IU
- 19 years and older: 3,000 mcg RAE or 10,000 IU
- Nursing Women
- 18 years old or younger: 2,800 mcg RAE or 9,320 IU
- 19 years and older: 3,000 mcg RAE or 10,000 IU
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. 2 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 . 3 In addition, relatively high intake of vitamin A (but notbeta-carotene) has been associated with increased risk of osteoporosis . 4 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. 5 Vitamin A may increase the anticoagulant effects of warfarin (Coumadin). 6 In addition, because vitamin A chemically resembles the drug isotretinoin (Accutane), it may amplify its toxic effects.
Interactions You Should Know About
If you are taking:
- Isotretinoin (Accutane) : Don't take vitamin A, as the two might enhance each other's toxicity.
- Valproic acid (Depakote, Depacon, or Depakene) and you are pregnant: Do not take vitamin A supplements unless advised to do so by a physician.
- Warfarin (Coumadin): Do not take vitamin A supplements unless advised to do so by a physician.
References
- 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.
- Alberts D, Ranger-Moore J, Einspahr J, Saboda K, Bozzo P, Liu Y, Xu XC, Lotan R, Warneke J, Salasche S, Stratton S, Levine N, Goldman R, Islas M, Duckett L, Thompson D, Bartels P, Foote J. Safety and efficacy of dose-intensive oral vitamin A in subjects with sun-damaged skin. Clin Cancer Res. 10(6):1875-80.
- Leo MA, Lieber CS. Alcohol, vitamin A, and beta-carotene: adverse interactions, including hepatotoxicity and carcinogenicity. Am J Clin Nutr. 69(6):1071-85.
- Melhus H, Michaëlsson K, Kindmark A, Bergström R, Holmberg L, Mallmin H, Wolk A, Ljunghall S. Excessive dietary intake of vitamin A is associated with reduced bone mineral density and increased risk for hip fracture. Ann Intern Med. 129(10):770-8.
- Nau H, Tzimas G, Mondry M, Plum C, Spohr HL. Antiepileptic drugs alter endogenous retinoid concentrations: a possible mechanism of teratogenesis of anticonvulsant therapy. Life Sci. 57(1):53-60.
- Harris JE. Interaction of dietary factors with oral anticoagulants: review and applications. J Am Diet Assoc. 95(5):580-4.
