Individual effects of dietary saturated fatty acids and fish oil on plasma lipids and lipoproteins in normal men.

Fish ingestion is associated with lower mortality from coronary heart disease (CHD). However, in some Western populations whose diets are rich in saturated fatty acids (SFAs), CHD mortality is consistently high despite high fish consumption. To study this paradox, we fed six healthy men diets with two amounts of SFA (5% and 19% of energy) that also differed in total fat (25% and 39% of energy). Each fat amount was given with and without n-3 fatty acids (FAs) (2% of energy) for 3 wk. On both the low and high SFA diets the presence of n-3 FAs significantly lowered plasma total cholesterol, very-low-density-lipoprotein cholesterol, (high-density-lipoprotein cholesterol (HDL-C), total triglyceride, and very-low-density-lipoprotein triglyceride. Compared with the high SFA diet, the low SFA diet decreased total cholesterol, low-density-lipoprotein cholesterol, and HDL-C. No interaction of SFA and n-3 FA was found. These results indicate that dietary SFAs and n-3 FAs have independent mechanisms of actions on the plasma lipids and lipoproteins. Optimal plasma lipids were produced by the diet low in SFA and high in n-3 FA.