CHICAGO -- Hippocrates was no hypocrite 2,500 years ago, and especially not by today's standards, when he said, "Let food be thy medicine and medicine be thy food." This tenet is the basis of the Institute of Food Technologists' (IFT's) Scientific Status Summary "Functional Foods: Their Role in Disease Prevention and Health Promotion," which examines the primary plant and animal foods that have been linked to non-traditional physiological benefits in the last decade.
Indeed, food and medicine are no longer separate topics, and the lines between them will continue to blur as scientists enhance their understanding of food components. New knowledge about non-traditional components in common foods, such as fruits and vegetables, has led to some of them being coined functional foods. These foods are defined as potentially providing health benefits beyond meeting basic nutritional needs. IFT's summary, published in the November 1998 issue of IFT's Food Technology, reviews the research to date on whole foods, rather than specific compounds isolated from foods, that demonstrate such benefits. These foods include oat and soy products, flaxseed oil, tomatoes, garlic, broccoli and other cruciferous vegetables, citrus fruits, cranberries, green tea, wine and grapes, fish, dairy products, and beef.
Summary author Clare M. Hasler, Ph.D., University of Illinois, noted that "overwhelming evidence from epidemiological, in vivo [in living animals], in vitro [in laboratory tests], and clinical trial data indicates that a plant-based diet can reduce the risk of chronic disease, particularly cancer." Recently identified biologically active plant chemicals, or phytochemicals, appear to account for this reduced risk in addition to standard nutrients. For example, lycopene, the primary phytochemical found in tomatoes, has been associated in human clinical trials with reducing the risk of prostate and other cancers. Limonoids in citrus fruits, glucosinolates in cruciferous vegetables, and catechins in green tea also appear to be protective against a variety of human cancers. Isoflavones in soy and lignans in flaxseed oil, which act as weak estrogens, may have a role in reducing the risk of breast cancer.
According to Hasler, the cholesterol-lowering effects of the soluble fiber ß-glucan in oats and soy compounds are well-documented. Hence, these foods are reputed to reduce the risk of cardiovascular disease, America's number one killer. Omega-3 fatty acids in flaxseed oil and fish also appear to reduce the risk of heart disease.
Research indicates that organosulfur compounds in garlic may have it all: cancer-fighting, cholesterol-lowering, antibiotic and anti-hypertensive properties, which would far outweigh the herb's ability to cause bad breath. Probiotics or friendly bacteria in fermented milk products, such as yogurt, also appear to have multiple benefits, Hasler noted. Probiotics have been associated with reducing the risk of colon cancer, lowering cholesterol, and out-competing potentially disease-causing bacteria in the gastrointestinal tract.
In her report, Hasler also stated that conjugated linoleic acid in beef may protect against a variety of cancers. This fatty acid increases in beef when it is cooked or otherwise processed.
"Those foods whose health benefits are supported by sufficient scientific substantiation have the potential to be an increasingly important component of a healthy lifestyle," Hasler said. "It should be stressed however, that functional foods are not a magic bullet or universal panacea for poor health habits. Emphasis must be placed on overall dietary pattern; one that follows the current U.S. Dietary Guidelines, and is plant-based, high in fiber, low in animal fat, and contains five to nine servings of fruits and vegetables per day." Physical activity, lowering stress, and not smoking should also be encouraged to promote wellness, she added.
Clare M. Hasler, Ph.D., is Executive Director of the Functional Foods for Health Program in the Department of Food Science and Human Nutrition at the University of Illinois at Urbana.
Founded in 1939, IFT is a non-profit scientific society of 28,000 members working in food science, technology and related professions in industry, academia, and government. As the society for food science and technology, IFT brings sound science to the public discussions of food issues.