Optimal nutrition.

An optimal diet cannot yet be defined. If we knew what an optimal diet was, additional research in nutrition would not be necessary. There is abundant evidence, however, that the usual American diet is not optimal and adequate reason to recommend modification. Current dietary recommendations were developed to prevent the occurrence of nutritional deficiency disease in the 1930's and 1940's. They have been largely successful. They were made, however, before any knowledge was available about the effects of diet upon chronic disease which now represent the primary health problems of the United States. Large amounts of data are available indicating the kids of recommendations which should be made to control hypercholesterolemia--a primary risk factor of coronary artery disease. These kinds of data together with less information upon diet and cancer, hypertension, obesity, diabetes, etc. lead to sensible and consistent dietary recommendations to moderate the dietary practices of most Americans.