Polyunsaturated and monounsaturated fatty acids in the diet to prevent coronary heart disease via cholesterol reduction.

For over 30 years the American Heart Association recommended to limit the fat intake to 30 energy % (E%) of total calories with 10 E% derived from polyunsaturated fatty acids (PUFA), 10 E% from monounsaturated fatty acids (MUFA) and 10 E% from saturated fatty acids (SFA). In 1988 and subsequent years, the National Cholesterol Education Program has changed this advise in favor of an increase of 15 E% MUFA and a reduction to 5 E% PUFA. This dramatic change was based largely on short-term dietary experiments, with formula diets with small numbers of subjects, and anecdotal epidemiological evidence from the population of Crete. The assertion that oleic acid may lower cholesterol and LDL remains unproven. However, isocaloric substitution of linoleic acid for oleic acid lowers cholesterol and LDL. Oleic acid has little or no effect on lipids and lipoproteins except as it replaces SFA. Large dietary feeding experiments in the 1950s and 1960s with persons with hypercholesterolemia and with patients after myocardial infarction were conducted with PUFA-enriched diets and proved effective in primary and secondary prevention of coronary heart disease. No such studies exist with MUFA-enriched diets. Therefore, the original recommendations remain the standard of dietary advise to healthy persons and patients after myocardial infarction.