Quantitative effects of dietary fat on serum cholesterol in man.

LTHOUGH many studies demonstrate that changes in the serum cholesterol level may be induced by modifying the amount or composition of dietary fat, the causal factors in oils and fats have not been clearly identified. T\4ajor emphasis has been placed upon the polyunsaturated fatty acids, both in the scientific and the popular press. Not all the evidence, however, supports this presumed primary role of polyunsaturated fatty acids nor will the conclusions of this paper. The principal conclusions regarding the relationship between various fat components and the level of serum cholesterol may be summarized as follows: (1) Ahrens et al) demonstrated a rough inverse relationship between the serum cholesterol level and the iodine number (total degree of unsaturation) of various oils. This conclusion implies that monounsaturated acids are half as effective as the diene, linoleic acid, the primary polyunsaturated acid in vegetable oils. The data seem to demonstrate that minimal levels of serum cholesterol were achieved with oils with an iodine number of about 100, and that more highly unsaturated oils were not more effective. Since all fats were fed at the same fat level, the effects of varying the amount