Effects of moderate (MF) versus lower fat (LF) diets on lipids and lipoproteins: a meta-analysis of clinical trials in subjects with and without diabetes

BackgroundDyslipidemia increases coronary heart disease (CHD) risk and often presents in diabetes, which amplifies risk of CHD. Lower fat (LF) diets increase triglyceride (TG) and decrease high-density lipoprotein cholesterol (HDL-C); moderate fat (MF) diets decrease TG and lower HDL-C less.ObjectiveTo quantify the magnitude of lipid and lipoprotein responses to MF versus LF cholesterol-lowering weight maintenance diets in subjects with and without diabetes.MethodsA meta-analysis of 30 controlled-feeding studies (n = 1213 subjects) was conducted to evaluate LF versus MF diets on lipids and lipoproteins in subjects with and without diabetes.ResultsIn all subjects, MF and LF diets decreased low-density lipoprotein cholesterol (LDL-C) similarly. MF diets decreased HDL-C less versus LF diets. The estimated increase in HDL-C after MF diets versus LF diets was 2.28 mg/dL (95% confidence interval 1.66 to 2.90 mg/dL, P < .0001). MF diets decreased TG, whereas LF diets increased TG. The decrease in TG was −9.36 mg/dL (−12.16 to −6.08 mg/dL, P < .00001) for MF versus LF diets. In subjects with diabetes, there was a similar increase in HDL-C (2.28 mg/dL) versus subjects without diabetes; however, there was a greater reduction in TG (−24.79 mg/dL, P < .05) on the MF diet. Subjects with diabetes had greater reductions in the total cholesterol (TC) to HDL-C ratio (TC:HDL-C) (—0.62, P < .0001) and non–HDL-C (−5.39 %, P < .06) after MF versus LF diets.ConclusionsBoth men and women had greater estimated reductions (6.37% and 9.34%, respectively) in predicted CHD risk after MF diets compared to LF diets. Moreover, based on greater reductions in TG, the TC:HDL-C ratio and non–HDL-C in subjects with diabetes, the CHD risk reduction would be greater for a MF versus a LF weight maintenance, cholesterol-lowering diet.