Effects of Reducing Dietary Saturated Fatty Acids on Plasma Lipids and Lipoproteins in Healthy Subjects

Abstract

Few well-controlled diet studies have investigated the effects of reducing dietary saturated fatty acid (SFA) intake in premenopausal and postmenopausal women or in blacks. We conducted a multicenter, randomized, crossover-design trial of the effects of reducing dietary SFA on plasma lipids and lipoproteins in 103 healthy adults 22 to 67 years old. There were 46 men and 57 women, of whom 26 were black, 18 were postmenopausal women, and 16 were men > or =40 years old. All meals and snacks, except Saturday dinner, were prepared and served by the research centers. The study was designed to compare three diets: an average American diet (AAD), a Step 1 diet, and a low-SFA (Low-Sat) diet. Dietary cholesterol was constant. Diet composition was validated and monitored by a central laboratory. Each diet was consumed for 8 weeks, and blood samples were obtained during weeks 5 through 8. The compositions of the three diets were as follows: AAD, 34.3% kcal fat and 15.0% kcal SFA; Step 1, 28.6% kcal fat and 9.0% kcal SFA; and Low-Sat, 25.3% kcal fat and 6.1% kcal SFA. Each diet provided approximately 275 mg cholesterol/d. Compared with AAD, plasma total cholesterol in the whole group fell 5% on Step 1 and 9% on Low-Sat. LDL cholesterol was 7% lower on Step 1 and 11% lower on Low-Sat than on the AAD (both P<.01). Similar responses were seen in each subgroup. HDL cholesterol fell 7% on Step 1 and 11% on Low-Sat (both P<.01). Reductions in HDL cholesterol were seen in all subgroups except blacks and older men. Plasma triglyceride levels increased approximately 9% between AAD and Step 1 but did not increase further from Step 1 to Low-Sat. Changes in triglyceride levels were not significant in most subgroups. Surprisingly, plasma Lp(a) concentrations increased in a stepwise fashion as SFA was reduced. In a well-controlled feeding study, stepwise reductions in SFA resulted in parallel reductions in plasma total and LDL cholesterol levels. Diet effects were remarkably similar in several subgroups of men and women and in blacks. The reductions in total and LDL cholesterol achieved in these different subgroups indicate that diet can have a significant impact on risk for atherosclerotic cardiovascular disease in the total population.

Dose Response of Almonds on Coronary Heart Disease Risk Factors: Blood Lipids, Oxidized Low-Density Lipoproteins, Lipoprotein(a), Homocysteine, and Pulmonary Nitric Oxide

“…MUFA has, however, been associated with higher HDL cholesterol concentrations, 15,30 reflected in lower total:HDL cholesterol and LDL-:HDL cholesterol ratios, as potentially important predictors of cardiovascular risk. 21 Higher SFA intakes in exchange for carbohydrate in the DELTA (Dietary Effects on Lipoproteins and Thrombogenic Activity) study were associated with a lower Lp(a) level, 31 an effect associated in the present study with higher MUFA intakes. This lipid risk factor for CHD is not altered by most dietary and pharmacological treatments, and the effect of almonds is therefore notable.…”

Serum lipid profiles in Japanese women and men during consumption of walnuts

“…In well-controlled studies with a large number of subjects (Ginsberg et al, 1998;Howard et al, 1995;Mensink & Katan, 1990), they showed that diet effects were similar in women and men when they investigated the effects of reducing the dietary saturated fatty acids on serum total and LDL cholesterol concentrations. In this study, the ratio of polyunsaturated to saturated fat was 3.0 in the walnut diet and 1.0 in the reference diet.…”

Differential Effect of National Cholesterol Education Program (NCEP) Step II Diet on HDL Cholesterol, Its Subfractions, and Apoprotein A-I Levels in Hypercholesterolemic Women and Men After 1 Year

“…However, most were short term, and only a few presented sex-specific results. The diet studies that have provided sex-specific data disagree, reporting similar HDL-C responses between women and men, 10,28,32,35 greater reductions in women, 7,8,31 and greater reductions in men. 38 The discrepancies in these reported results may reflect the differences in study protocols, including subject characteristics, provided versus selfselected foods, nutrient composition, and usually short study duration.…”