The impact of dietary mono- and poly-unsaturated fatty acids on risk factors for atherosclerosis in humans

Abstract

The fatty acid composition of the diet has various effects on atherosclerosis risk factors. Dietary saturated fatty acids (SFA) and trans-unsaturated fatty acids increase the low-density lipoprotein (LDL)-/high-density lipoprotein (HDL)-cholesterol ratio in serum, while these fats do not have a significant bearing on serum triglyceride levels. By contrast, dietary monounsaturated fatty acids (MUFA), n-6 polyunsaturated fatty acids (PUFA), and α-linolenic acid (C18:3n-3) similarly reduce LDL cholesterol concentrations, while their influence on serum HDL cholesterol and triglycerides is not appreciable. Dietary long-chain n-3 PUFA slightly increase serum LDL cholesterol concentrations, but are nevertheless considered salubrious with regard to serum lipids due to the distinct triglyceride-lowering effects. MUFA-rich compared to n-6 PUFA-rich diets strongly reduce the in vitro oxidizability of LDL. The available studies on this subject also suggest that n-3 PUFA in the small amounts usually present in the diet are not unduly harmful. These findings are consistent with reports from observational studies: the amount of SFA is positively and the amount of MUFA and n-6 PUFA in the diet is inversely associated with the risk of cardiovascular disease in most epidemiological studies. The available studies have had an impact on current dietary guidelines, which unanimously recommend that most of the dietary fat should be in the form of MUFA, while the amount of SFA and trans fatty acids in the diet should be as low as possible.