DIETARY SUPPLEMENT USE IN DISEASE PREVENTION IS A "CHEAP INSURANCE"

DIETARY SUPPLEMENT USE IN DISEASE PREVENTION IS A "CHEAP INSURANCE" for certain illnesses, Gladys Block, PhD, University of California-Berkeley, suggested at the Fourth International Conference of Anticarcinogenesis and Radiation Protection in Baltimore on April 22. Block asserted that researchers should back away from the position that "you shouldn't take supplements. . . There really isn't evidence that antioxidant-like nutrients are harmful and maybe they're helpful." "In the context of our [escalating] health care costs," Block continued, we need to prevent cancer and other diseases. Dietary supplements are "a cheap insurance for preventing" these illnesses, she maintained. One of 10 participants at a "roundtable discussion" entitled, "Strategies for Cancer Prevention: Diet, Foods, Additives, Supplements and Drugs," Block did not favor dietary supplements as the most effective nutritional approach to cancer and disease prevention: "I think we should be moving toward fortifying the food supply" with antioxidant nutrients, she argued. "There are lots of things in fruits and vegetables that you can't get in a pill and never will get in a pill," she declared. A former National Cancer Institute employee, Block acknowledged the benefits of the American Cancer Society's recommendation to consume five servings of fruits and vegetables each day as a legitimate chemopreventive measure. She warned, however, that since "only 9% of the population on any given day has that five servings of fruits and vegetables," it is a "public health mistake to say, 'That's the only way to go.'" Fortification of the food supply could augment the ACS suggestion, Block indicated. Kathy Helzlsouer, MD, Johns Hopkins School of Hygiene & Public Health, agreed with Block that dietary supplements would play only a limited role in the prevention of cancer and noted that supplements did not "compensate" for poor eating habits. A March 1993 report issued by the research committee of the Institute of Food Technologists included a study that echoed the opinions of the roundtable panelists: "Not only does absorption of nutrients occur more favorably in the presence of the myriad of components in foods that are typically absent from supplements, but also emerging research findings indicate that non-nutritive substances in food, such as fiber, have beneficial effects on health." All of the panel members supported the view that vitamin C, vitamin E, beta carotene and antioxidants provide chemopreventive benefits. However, most of the panel did not believe that currently available data were sufficient to recommend chemopreventive health claims for those nutrients. "How much proof do we need in order to reach the point where we can take some public health action?" Block asked. "The epidemiology is extremely impressive." Regarding clinical data supporting chemopreventive health claims, she noted, "I very much approve, . . . but they will give us a small number of limited and specific answers to limited and specific questions." For example, "most of the beta carotene studies are being done with 30 mg of beta carotene. It won't tell us anything about 10 mg of beta carotene or levels that are achievable in diet. It won't tell us anything about combinations," she argued. Lee Wattenberg, MD, American Association for Cancer Research president and a professor at the University of Minnesota, offered general support for additional research on the potential chemopreventive benefits of nutritionals. "I think that when these recommendations are made they should be tested just the way we would test a . . . medicinal," he said. "I don't think these recommendations should just be thrown out to the public and say, 'Look, this is good,' without conducting controlled trials."