Anti-oxidant research is incomplete

ON CALL

April 26, 1994|By Dr. Simeon Margolis | Dr. Simeon Margolis,Special to The Sun

Q: On my doctor's advice I have been taking vitamin E and beta carotene to protect against a heart attack. Now I am not sure whether to continue, because a recent article in the New York Times described a study which showed that they provided no benefit against cancer or heart disease, and that they might be harmful.

A: Many physicians have recommended supplements of one or more of the three anti-oxidants -- vitamins C and E and beta carotene -- because they believed them to be safe and to possibly delay or prevent coronary artery disease. Test-tube experiments and animal studies, as well as population studies in people, have provided suggestive evidence that such anti-oxidants may slow the development of hardening of the arteries by preventing the oxidation of low density lipoprotein (LDL), which leads to its deposition in the arterial wall. The evidence for protection against coronary disease is best for vitamin E. But there is still no proof that these anti-oxidants are beneficial. The article referred to a study of about 29,000 male smokers from Finland between the ages of 50 and 69. The participants took either a sugar pill, vitamin E alone, beta carotene alone, or both vitamin E and beta carotene for about six years. The aim was to determine whether vitamin E or beta carotene would reduce the incidence of cancers. The men who took beta carotene had a higher incidence of lung cancer than those who did not. Although this may be due to chance, it does raise concerns about safety of taking large amounts of beta carotene over a long period of time. Vitamin E intake did not affect total mortality, but there were more deaths from hemorrhagic strokes in those taking this vitamin. Neither vitamin E nor beta carotene reduced the incidence of coronary heart disease.

The results of the Finnish study suggest that older male smokers should be cautious about taking supplements of beta carotene. If cigarette smokers really want to reduce their risk, they should stop smoking.

Dr. Margolis is professor at the Johns Hopkins School of Medicine.

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