The bottom line on supplements.

Many health-minded individuals, including athletes, tend to think that when it comes to vitamins, more is better. Vitamins are carbon-containing substances, necessary in minute amounts for normal metabolism. Deficiencies of vitamins result in specific disorders, but there is also a risk with some vitamins in taking larger amounts than the body requires. Further, synthetic supplements (as opposed to the naturally occurring substances found in whole foods) do not necessarily function in the same way as their natural counterparts and can sometimes produce unwanted consequences.

"The Medical Letter," a highly respected newsletter about drugs published for doctors, has recently reported its findings on vitamin supplements, and its conclusions might seem surprising, especially to those who subscribe to the "more is better" view. Combing the research for high-quality studies that support the benefits of taking vitamin supplements, the authors found that in only two cases was supplementation warranted. Women of childbearing age should take folic acid, and the elderly should possibly take B12 and vitamin D. Folic acid has been shown to dramatically decrease the incidence of neural tube defects when taken early in pregnancy. Elderly people have a decreased capacity to absorb B12 and often do not expose themselves to vitamin D generating sunlight. According to these researchers, the rest of us should save our money.

In addition to being at best a benign waste of valuable resources (Americans as a whole spend four billion dollars a year on dietary supplements), several studies show real risks associated with vitamin supplements. One large, double-blind study of beta carotene and vitamin A, for example, was stopped early because the supplements were associated with an increase in lung cancer and overall mortality. The authors concluded from that and several other studies, that no one should take beta carotene in the form of supplements.

Vitamin E is found in whole foods in the form of gamma-tocopherol and is a powerful antioxidant, which is why there is a great deal of interest in vitamin E supplementation. However, there is good research to show that alpha-tocopherol which is the most common form of vitamin E found in supplements, may actually have a pro-oxidant effect in the body. High doses of vitamin E may also interfere with vitamin K metabolism and the function of platelets. Certainly with regard to vitamin E there is controversy, with many medical experts taking a more positive spin on the research.

Although not all the good research is negative, vitamin C (do you know anyone who doesn't take extra vitamin C?) has also been shown to cause problems. It can have a pro-oxidant effect in the body; can cause diarrhea in doses over 1,000 mg per day; may increase the incidence of kidney stones; and, hard as they've tried, no research has shown vitamin C to prevent upper respiratory tract infections. However, research does seem to indicate that vitamin C helps reduce symptoms in colds, and their duration.

Multivitamin preparations usually contain safe amounts of vitamins and minerals, and therefore may be insurance against gaps in modem diets. However, a balanced diet, with loads of fruits and vegetables and non-fat dairy is still the very best way to derive the health benefits of vitamins and minerals. In addition, you benefit from the host of phytochemicals present in whole foods known to reduce cancer and coronary disease risk.

Many may view the conclusions of "The Medical Letter" editors as too conservative. Be that as it may, the next time you think about buying expensive vitamins, you may want to weigh in their opinions. It may be wiser to take a U-turn to the produce section and load up on fresh fruits and vegetables-no risks at all, and lots of proven benefits.

(The Medical Letter, 1998, Vol. 40, No. 1032, pp. 75-77)