Evidence and proof in making policy decisions

General dietary guidelines for the public are established to minimize risk. Recommended intakes of essential nutrients--the RDAs--are established at levels believed to be substantially above those required by most individuals in order to minimize the risk of deficiency of those with highest requirement. Such levels of intake do not benefit most individuals, cannot be proved to be correct since few individuals benefit, may mislead some individuals as to the benefits to be derived from such diets, but are defensible on the basis that they are probably helpful for a few and impose no health risk. They do impose unnecessary food selection for most people. Recommended intakes of fat, cholesterol, sugar, salt, toxic materials, etc.--food constituents that impose risks at higher intakes--must also be developed to minimize risk. No advantages are claimed for high intakes of the above. Abundant evidence, epidemiologic, clinical, and experimental, identifies high intakes as imposing substantial risk. The nature of chronic diseases associated with excessive intake, which may require 10-30 years before effects are manifest, precludes adequate experiments to definite the results associated with dietary change. The only rational position that can be taken is to recommend reduced intakes consistent with various practical restraints.