FOR MILLIONS OF HEALTH-CONSCIOUS Americans, antioxidant vitamins are a way of life. Revered for their power to sub-due "free radicals"the molecular vandals that erode our youth, harden our arteries and turn our cells cancerous-antioxidant supplements have sold wildly in recent years. In 1993 alone, store sales of vitamin E supplements grew by 39 percent (to $123 million), while beta-carotene sales soared by 31 percent (to $22 million) and vitamin C sales rose 10 percent (to $117 million). The latest intelligence on such pills, reported in last week's New England Journal of Medicine, is sure to confuse, even frighten, some devotees. After treating 29,000 male Finnish smokers with vitamin E and beta carotene for five to eight years, researchers concluded that the supplements "may actually have harmful as well as beneficial effects." But the findings don't prove that supplements are worthless or dangerous. The lesson is simply that pills are no substitute for common sense.
The evidence linking vitamins to better health is considerable. No one denies that folic acid (one of the B vitamins) can help prevent birth defects. And epidemiologic studies, which track broad patterns of diet and disease in the population, suggest that vitamin C can reduce the risk of mouth, throat and stomach cancers, that vitamin D may help prevent breast, bowel and prostate cancers, and that vitamin E can reduce the risk of heart disease. in a pair of studies published last year, Harvard researchers found that people who reported taking at least 100 milligrams of vitamin E daily suffered 40 percent less heart disease than people who got less of the vitamin. Though beta carotene (an A vitamin) failed to protect smokers from lung cancer in the newly reported intervention trial, more than 20 epidemiologic studies have linked high intake of the vitamin to low rates of the disease.
The trouble with such studies is that they don't prove cause and effect. Diets that are rich in particular vitamins contain other nutrients as well, and people with high vitamin intakes may share other characteristics that protect them from disease. The U.S. Food and Drug Administration (FDA) is satisfied that foods rich in vitamin E and beta carotene can help prevent cancer. That's why the agency recommends eating five servings of fruit and vegetables daily. But until controlled studies establish that supplements alone bring the same benefits, the agency isn't authorizing health claims for them.
Though supplements didn't perform well in the controlled study reported last week, they may still have a legitimate place in the cupboard. Interpreted narrowly, the latest findings show only that particular vitamins, at particular doses, don't reduce the hazards of smoking among Finnish men. Administered differently, or for longer periods, the same vitamins might make a different impression. Researchers at the National Cancer Institute reported last fall that a similar regimen (including supplements of vitamin E, beta carotene and the mineral selenium) reduced the cancer death rate by 13 percent among 29,000 adults in northern China.
Experts aren't terribly worried about the safety implications of the Finnish study (in which supplement takers suffered slightly higher mortality). As the FDA noted in a briefing paper for agency employees, "the majority of vitamin and mineral supplements consumed today-particularly multivitamin/multimineral products containing nutrients at levels consistent with recommended daily amounts-do not raise safety concerns." The dozen or so controlled trials now underway will tell us more about the risks and benefits of various supplements. But until the evidence is in, consumers will have to accept that they may be wasting their money.
Despite last week's sobering findings, millions of Americans are turning to vitamins to improve their health.
The following charts reads as follows: VITAMIN; FOOD SOURCE/BENEFITS; % INCREASE IN SALES, 92-93.
Plentiful in peaches, apricots and yellow vegetables. Benefits: Indirect evidence suggests it can help prevent cancer.; 31%
The B vitamins are found in a range of foods. Benefits: B6 may bolster immunity and B12 helps maintain healthy cells.; 7%
Citrus fruits, red peppers and berries are good sources. Benefits: May control the tissue damage that leads to cancer.; 10%
Best sources are canned sardines, fortified milk and sunshine. Benefits: Strengthens bones and may help prevent some cancers.; --
Hard to get from food, but found in wheatgerm and nuts. Benefits: High doses may reduce the risk of heart disease.; 39%
Liver and leafy greens are rich sources. Benefits: Supplements can help women prevent birth defects.; --
Plentiful in peas, peanut butter and some meats. Benefits: High doses can help people lower their cholesterol.; --
SOURCES: "THE DOCTORS' VITAMIN AND MINERAL ENCYCLOPEDIA," "THE ESSENTIAL GUIDE TO VITAMINS AND MINERALS," TOWNE-OLLER & ASSOCIATES