A diet restricted in saturated fat and cholesterol is recommended for subjects with elevated LDL cholesterol concentrations before and during drug therapy. Gender differences in lipoprotein subspecies response to such diets have not been studied in detail. We examined the effects of a diet low in total fat, saturated fat and cholesterol (Therapeutic Lifestyle Changes, TLC, diet: 26% of energy as fat, 4% as saturated fat, and 45 mg cholesterol/4.2 MJ), compared with an average American diet (AAD: 35% of energy as fat, 14% as saturated fat, and 147 mg cholesterol/4.2 MJ), on plasma lipoprotein subspecies in men and women. Each diet period lasted 6 wk. Body weight was kept constant during each diet period. Men (n = 19) and postmenopausal women (n = 14) >40 y old with moderate hypercholesterolemia participated in this study. Plasma lipoprotein concentrations were assessed by standardized methodology, and lipoprotein sizes were determined by gradient gel electrophoresis and NMR spectroscopy. The TLC diet resulted in greater reductions in total cholesterol and plasma apolipoprotein B concentrations in men than in women (-19% vs. -12%, P < 0.05, and -18% vs. -9%, P < 0.05, respectively). Postprandial triacylglycerol and LpAI:AII concentrations were reduced in men, but not in women (-15% vs. 8%, P < 0.05, and -9% vs. -2%, respectively, P < 0.05). Similar decreases in LpAI concentrations and LDL and HDL particle size were observed in men and women. These data are consistent with the concept that middle aged/elderly men may have a more favorable lipoprotein response to a low fat, low cholesterol diet than postmenopausal women.
We tested the effects of a National Cholesterol Education Program (NCEP) Step 2 diet (30% of calories or less as total fat, less than 7% saturated fat, and less than 200 mg cholesterol per day) on plasma lipid levels in normocholesterolemic and hypercholesterolemic middle-aged and elderly men and women. Thirty-two subjects were studied. Eight normolipidemic subjects (6 men and 2 women, mean age 56 +/- 13 years) with LDL cholesterol levels of less than 4.14 mmol/L (160 mg/dL) were given a baseline diet similar in composition to the diet currently consumed in the United States (35% of calories as total fat and 14% as saturated fat, with 147 mg cholesterol per 1000 kcal) for 6 weeks. Subjects were then placed on an NCEP Step 2 diet (26% total fat, 4% saturated fat, 45 mg cholesterol per 1000 kcal) for 24 weeks. In addition, 24 subjects (12 men and 12 women, mean age 62 +/- 12 years) with moderate hypercholesterolemia (LDL cholesterol levels of 4.14 mmol/L or above) were given a baseline diet for 6 weeks and then the NCEP Step 2 diet for 6 weeks. Energy intakes were adjusted to keep body weight constant throughout the study. In both normolipidemic and hypercholesterolemic subjects, consumption of the NCEP Step 2 diet was associated with significant changes in levels of total cholesterol (-20% and -16%, respectively), LDL cholesterol (-21% and -18%, respectively), and HDL cholesterol (-16% and -15%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
We examined the mechanisms responsible for the decrease in HDL cholesterol (HDL-C) levels after the consumption of a diet low in total fat, saturated fat, and cholesterol. Twenty-one subjects with a mean age of 58+/-12 years were placed on a baseline isocaloric diet (15% protein, 49% carbohydrate, 36% fat, and 150 mg/1000 kcals of cholesterol) and then switched to an NCEP Step 2 diet (15% protein, 60% carbohydrate, 25% fat, and 45 mg/1000 kcals of cholesterol). After 6 or 24 weeks on each diet, subjects received a 15-hour primed-constant infusion of [5,5,5-2H3]-L-leucine. HDL apoA-I and apoA-II tracer curves were determined by gas chromatography-mass spectrometry and fitted to a monoexponential equation. Compared with the baseline diet, consumption of the Step 2 diet lowered HDL-C mean levels by 15% (1.03+/-0.23 to 0.88+/-0.16 mmol/L, P<0.001), apoA-I by 12% (1.25+/-0.15 to 1.10+/-0.13 g/L, P<0. 001) and the TC/HDL-C ratio by 5% (0.145+/-0.04 to 0.137+/-0.03). No significant changes were observed in apoA-II levels and HDL particle size with diet. HDL apoA-I fractional catabolic rate did not change (0.219+/-0.052 to 0.220+/-0.043 pools/day, P=0.91) but HDL apoA-I secretion rate decreased by 8% (12.26+/-3.07 to 10.84+/-2.11 mg. kg-1. day-1, P=0.03) during consumption of the Step 2 diet. There was no effect of diet on apoA-II fractional catabolic rate or secretion rate. Our results indicate that the decrease in HDL-C and apoA-I levels during the isocaloric consumption of a Step 2 diet paralleled the reductions in apoA-I secretion rate.
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