One of the most fascinating areas of research on food ingredients concerns the possible role of antioxidant vitamins in the prevention of disease.
Two years ago, Time magazine published a cover story on vitamins citing new research showing that they may prevent cancer, heart disease and aging. Since these may well be the three greatest fears of the health-conscious American public, it is no surprise that many of us -- even many of the experts -- began taking vitamin supplements. In 1993, vitamins mushroomed into a $4 billion industry in the United States. The antioxidant vitamins -- vitamin C, vitamin E and beta-carotene (the precursor to vitamin A) -- account for one-fourth of the industry, or about $1 billion. They have received the greatest attention because of their ability to destroy free radicals in the body.
Free radicals are molecular fragments that may cause tumor formation, promote heart and lung diseases, and contribute to the gradual aging processes. Research studies supporting the positive effects of antioxidant vitamin supplements include:
· A study sponsored by the National Cancer Institute that involved 30,000 participants in rural China. It found a reduction in cancer death rates for those who consumed a supplement combining selenium, vitamin E and beta-carotene. · A Harvard Medical School report on 22,000 male physicians whose health was monitored over 10 years. Among participants with a history of cardiac disease who consumed beta-carotene supplements, a 50% reduction in heart attacks, strokes and deaths was demonstrated compared with the control group. · A study conducted by Harvard University and Brigham and Women's Hospital on more than 100,000 male and female health professionals. It found in both gender groups a large reduction in risk of heart disease among participants who consumed vitamin E supplements. Other major studies are ongoing. Additional epidemiologic evidence exists showing that population groups with diets rich in these vitamins have lower incidence of many forms of cancer. This is compelling evidence. Some public interest groups have responded by recommending supplementation of the diet with antioxidant vitamins. Recent studies, however, have resulted in serious questions about the wisdom of these recommendations. One of these, dubbed the "Finnish study" in the popular press, was sponsored by NCI and the National Public Health Institute of Finland. It found an 18% increase in the incidence of lung cancer among smokers taking beta-carotene supplements. The other study, published recently in the New England Journal of Medicine, reported that 864 subjects who consumed one of four supplement regimes involving combinations of vitamin C, vitamin E and beta-carotene did not show lower risk of colon cancer. In a recent article published in the American Journal of Clinical Nutrition, author Victor Herbert asserted that antioxidant supplements will not provide the same benefits as those naturally present in food because they are "unbalanced biochemistry"; that is, only present in reduced form. Antioxidant vitamins naturally present in food exist half in oxidized form and half in reduced form. Thus, Mr. Herbert postulated, the "unbalanced" supplements may actually have harmful pro-oxidant effects. This opinion may not be shared by other experts. However, in antioxidant vitamins, as in other areas of nutrition-related research, it appears that answers about diet and disease are far from clear.
C. Gail Greenwald is vice president and managing director of technology consulting for Arthur D. Little Inc., Cambridge, Mass.