WHOLE FOODS VERSUS INDIVIDUAL NUTRIENTS
|The fourteen dietary recommendations by
the World Cancer Research Fund and the American Institute
for Cancer Research (WCRF/AICR) have as a goal the
prevention of cancer from dietary related causes. The
recommendations emphasize for the most part, whole
foods rather than individual dietary nutrients.
During the 1920s to 1950s research was concerned with finding the amounts of individual nutrients needed to avoid or treat classic deficiency diseases. For instance, the minimum amount of vitamin C needed to prevent scurvy was found to be between 8 and 10 milligrams per day. This step was followed by the development of the Recommended Dietary Allowances (RDA). The RDAs took into account an estimated range of need by a population. So a safety factor was added to the original figure of 8 to 10 mg to assure the protection of practically all individuals (97-98 percent) within a population. Finally, the RDA for vitamin C was set at 60 milligrams daily in this country.
The recommendations made for this and other single dietary constituents like vitamin A, thiamin, riboflavin, iron, folate, vitamin E, and the like have encouraged the misconception that the key factors in chronic diseases are single or maybe several specific nutrients.
For instance, preliminary research had indicated that beta-carotene, vitamins C and E and selenium were key dietary nutrients in the protection against several cancers. Later research showed that carotenoids (not beta-carotene specifically) and vitamin C may provide protection. However, when these conclusions were tested by supplementing the diet with these specific nutrients, provided singly or in combination, the results were not clear. To single out the nutrient(s) most researched, or most easily measured, or best known as an antioxidant of choice, against cancer is a mistake. The present evidence makes it appropriate to conclude that foods rich in antioxidants and bioactive compounds, mainly vegetables and fruits, protect against cancer. The effect of the whole food is more powerful than the effect of a specific dietary nutrient. In other words, the individual food substances may protect against cancer not as a single agent, but in the combination as they are naturally found in foods. It is only when the scientific evidence is strong enough that the panel will include recommendations on specific dietary substances. Otherwise, the recommendations are based on foods and drinks.
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Prepared 1998 by Bernadene Magnuson, Ph.D.
University of Idaho, Dept. of Food Science and Toxicology - EXTOXNET FAQ Team.