Effects of National Cholesterol Education Program Step 2 diets relatively high or relatively low in fish-derived fatty acids on plasma lipoproteins in middle-aged and elderly subjects.

The effects of two National Cholesterol Education Program (NCEP) Step 2 diets (< or = 30% of energy as total fat, < 7% of energy as saturated fat, and < 200 mg cholesterol/d), one relatively high and the other relatively low in fish-derived fatty acids, on plasma lipoprotein concentrations and blood pressure were compared in 22 men and women with a mean (+/- SD) age of 63 +/- 10 y. Subjects were placed on a baseline diet similar to the diet currently consumed in the United States (35% of energy as total fat, 14% of energy as saturated fat, 35 mg cholesterol/MJ) for 6 wk and then on either an NCEP Step 2 diet relatively high in fish (Step 2 high-fish, n = 11) or relatively low in fish (Step 2 low-fish, n = 11) for 24 wk. All food and drinks were provided. Compared with baseline values, consumption of both the Step 2 high-fish and the Step 2 low-fish diets under weight-stable conditions was associated with significant decreases in plasma concentrations of total cholesterol (-14% and -19%, respectively), low-density-lipoprotein (LDL) cholesterol (-15% and -20%, respectively), and high-density-lipoprotein (HDL) cholesterol (-11% and -17%, respectively). Postprandial, but not fasting, triacylglycerol concentrations were significantly reduced during consumption of the Step 2 high-fish diet. There were no significant changes in these indexes after consumption of the Step 2 low-fish diet compared with the baseline diet. LDL particle size decreased significantly (-12%) only in subjects on the Step 2 low-fish diet. Both Step 2 diets caused small but significant reductions in diastolic blood pressure. Our results indicate that NCEP Step 2 diets relatively high or relatively low in fish are both effective in significantly reducing total and LDL-cholesterol concentrations without changes in the ratio of total cholesterol to HDL cholesterol under controlled weight-stable conditions in middle-aged and elderly subjects. A beneficial effect on diastolic blood pressure was also observed.