Just an addendum concerning safety of vitamin A. First, here is a list of vitamin A content of a few foods, in IUs per 100 grams. The richest source is obviously liver. ------------------------------------------ Beef liver, raw 35346 Beef liver, cooked, braised 35679 Lamb liver, raw 24612 Chicken liver, raw 20549 Butter 3058 Egg yolk, raw 1945 ------------------------------------------ As seen below, vitamin A is important for child development, but intakes much higher than 10000 IUs a day are not recommended, especially for pregnant women (teratogenicity=risk of birth defects). This corresponds to about 1.5 chicken liver/day, or 1 oz. beef liver/day. So, risks indeed exist, but people eating much more than 1.5 chicken liver/day are probably rare. -------------------------------------------------------------------- Am J Med 1994 Dec;97(6):523-528, Vitamin A hepatotoxicity: a cautionary note regarding 25,000 IU supplements, Kowalski TE, Falestiny M, Furth E, Malet PF Vitamin A hepatotoxicity has been reported at doses exceeding 50,000 IU/day. At 25,000 IU vitamin A per day, although elevated liver enzymes may be seen, hepatotoxicity is rare. We report a case of severe hepatotoxicity associated with the habitual daily ingestion of 25,000 IU of vitamin A bought as an over-the-counter dietary supplement. With the general availability of high-dose supplements and recent literature emphasizing the importance of vitamin A adequacy, the potential for vitamin A hepatotoxicity may increase. Health professionals should remain aware of the potential for vitamin A hepatotoxicity and elicit a vitamin A history in all patients being evaluated for liver dysfunction. ---------------------------------------------------------------------- N Engl J Med 1995 Nov 23;333(21):1369-1373, Teratogenicity of high vitamin A intake, Rothman KJ, Moore LL, Singer MR, Nguyen US, Mannino S, Milunsky A BACKGROUND. Studies in animals indicate that natural forms of vitamin A are teratogenic. Synthetic retinoids chemically similar to vitamin A cause birth defects in humans; as in animals, the defects appear to affect tissues derived from the cranial neural crest. METHODS. Between October 1984 and June 1987, we identified 22,748 pregnant women when they underwent screening either by measurement of maternal serum alpha-fetoprotein or by amniocentesis. Nurse interviewers obtained information on the women's diet, medications, and illnesses during the first trimester of pregnancy, as well as information on their family and medical history and exposure to environmental agents. We obtained information on the outcomes of pregnancy from the obstetricians who delivered the babies or from the women themselves. Of the 22,748 women, 339 had babies with birth defects; 121 of these babies had defects occurring in sites that originated in the cranial neural crest. RESULTS. For defects associated with cranial-neural-crest tissue, the ratio of the prevalence among the babies born to women who consumed more than 15,000 IU of preformed vitamin A per day from food and supplements to the prevalence among the babies whose mothers consumed 5000 IU or less per day was 3.5 (95 percent confidence interval, 1.7 to 7.3). For vitamin A from supplements alone, the ratio of the prevalence among the babies born to women who consumed more than 10,000 IU per day to that among the babies whose mothers consumed 5000 IU or less per day was 4.8 (95 percent confidence interval, 2.2 to 10.5). Using a smoothed regression curve, we found an apparent threshold near 10,000 IU per day of supplemental vitamin A. The increased frequency of defects was concentrated among the babies born to women who had consumed high levels of vitamin A before the seventh week of gestation. CONCLUSIONS. High dietary intake of preformed vitamin A appears to be teratogenic. Among the babies born to women who took more than 10,000 IU of preformed vitamin A per day in the form of supplements, we estimate that about 1 infant in 57 had a malformation attributable to the supplement. -------------------------------------------------------------------------- Am J Clin Nutr 1994 Feb;59(2 Suppl):517S-522S, Maternal vitamin A status and its importance in infancy and early childhood, Underwood BA Early fetal vitamin A supplies must be regulated to avoid teratogenic consequences from too little or too much. Late in gestation, adequate maternal vitamin A status is important for newborn reserves and for sustaining adequate breast-milk concentrations. Vitamin A supplements are not needed for most pregnant women in Western countries who consume the recommended dietary allowance during their reproductive years. Increased consumption of vitamin A-rich foods can meet increased needs during lactation. Women in developing countries whose habitual intakes are near basal needs should receive an additional 100 micrograms retinol equivalents (RE) during pregnancy and 300 micrograms RE during lactation. Supplements not above 3000 micrograms RE (10,000 IU) daily are safe for fertile women where circumstances preclude obtaining the needed increment through diet. The first postpartum month is the only safe period during which to provide deficient lactating women with a single high-dose supplement to benefit the mother and breast-feeding infant for several months.