The Austin Chronicle

To Your Health

By James Heffley, Ph.D., June 22, 2001, Columns

Q: Now that I am pregnant, my mother-in-law is very concerned about the vitamin A in a multivitamin I have used for years. Am I endangering my baby?

A: Pregnancy leads to many changes in your nutrient requirements, mostly to an increase in the need for certain vitamins and minerals. For years, physicians have been comfortable prescribing prenatal vitamin supplements and research vindicates the practice. The primary difference between a prescription prenatal formula and a formula you can obtain without a prescription is the amount of folic acid: 1,000 mcg in the prescription product compared to 800 mcg in nonprescription products. Abundant research in the past decade verifies that present-day prescription prenatals would be improved by the addition of certain minerals such as chromium and selenium to their formula. Likely these are in your current "regular" multivitamin/mineral. You can also add a separate folic acid supplement to your regular multivitamin/mineral.

However, more is not always better and certain nutrients deserve closer examination. A 1995 article in the New England Journal of Medicine warned that vitamin A in amounts over 8000 IU per day might lead to an increase in birth defects, specifically cleft palate. The article prompted an immediate reduction in the vitamin A content of most multivitamins, not just prenatal formulas.

Responsible scientists since 1995 have looked more closely at the incidence of birth defects among women taking supplements of vitamin A as high as 300,000 IU per day. Their report in the journal Teratology comes to quite different conclusions from the earlier report. Infants born to mothers taking lower amounts of vitamin A, up to 40,000 IU per day, suffered more birth defects than those born of mothers using about 50,000 IU per day. Questions remain regarding the potential for birth defects when pregnant women use extremely high amounts of vitamin A, 200,000 to 300,000 IU per day.

Animal research from the 1930s also sheds some light. When rats receive about half the rat RDA (Recommended Daily Allowance) of vitamin A, they tend not to reproduce at all. When they do, they tend to have rat pups with malformations of various sorts. As the amount of vitamin A in their diet is increased, they tend to be healthier and to have normal offspring, and maximum litter size (recognized as one measure of health in rats) requires the human equivalent of about 30,000 IU of vitamin A per day. This is in the ballpark of the amount mentioned in the second study, which apparently minimized birth defects in humans.

Laboratory research should never be applied directly to human experience because laboratory conditions are not the same as the real world. Human experience and animal research, however, consistently indicate that we ordinarily receive less than the ideal amounts of most nutrients from our Standard American Diet (some are fond of calling it the SAD diet). Research indicates that supplements of most nutrients in the range of two to five times the RDI (Recommended Daily Intake) are safe and beneficial in most circumstances, including a normal pregnancy. This does not mean that 100,000 IU (about 10 times the RDI) of vitamin A is safe. However, it looks like the restriction of vitamin A supplements among pregnant women to 8,000-10,000 IU per day was premature.

Use the occasion of your pregnancy as motivation to relax, improve your diet, and concentrate on improving your life. Your regular multivitamin/ mineral, with some extra folic acid, even with 15,000-25,000 IU of vitamin A, should be fine.

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