Abstract P064: Weight Loss Induced by Healthy Diets Reduces Atherogenic Lipoproteins that Contain ApoC-III Independent of Dietary Macronutrient Content
Background: Weight-loss improves lipid risk factors for cardiovascular disease risk. However, the effect of weight loss on VLDL, LDL and HDL subtypes that contain apoC-III, newly emerging as important predictors of CVD, is not known. Further, the effects of dietary macronutrient composition on changes in apoC-III-containing lipoproteins in the presence of weight loss have not been studied.
Methods: The Pounds Lost Trial randomized 811 overweight and obese subjects to four healthful diets that varied in emphasis of unsaturated fat, protein, and carbohydrate for 24 months. A random 50% subsample was selected for analysis of lipoprotein subfractions (~100 per study diet). Plasma samples were collected at baseline and after 24 months and stored at -80C to await analysis. Whole plasma was fractionated first by apoC-III content and then by density (VLDL, IDL+LDL, HDL) to produce 6 subfractions: VLDL with apoC-III, VLDL without apoC-III, IDL+LDL with apoC-III, IDL+LDL without apoC-III, HDL with apoC-III, HDL without apoC-III. Apolipoprotein and lipid concentrations were measured in these subfractions. The primary aim was to determine whether macronutrient content of diets for weight loss influenced changes after weight loss in concentrations and compositions of the 6 lipoprotein subfractions. A secondary analysis determined the relation between amount of weight-loss and change in the lipoproteins, adjusted for baseline BMI, age, race, and sex.
Results: On average, the study population had lost 5% of their body weight at 2 years regardless of randomized diet group. Changes in lipoprotein subfractions from baseline to 2 years were similar among the 4 diet groups. Multiple regression analysis determined that degree of weight loss significantly predicted reductions in apoC-III in VLDL, LDL and HDL. For example, a 5% weight loss corresponded to reductions in apoC-III in VLDL of 14% (95% CI: 8.0%, 19.8%), LDL of 5.5% (0.3%, 8.6%), and HDL of 2.2% (0.1%, 4.4%). Weight loss notably predicted a decrease in the apoB concentration of LDL with apoC-III. The concentration of LDL with apoC-III was the strongest predictor of CVD in several cohorts. In contrast, weight loss predicted increases in apoE in VLDL and LDL. ApoE increases the clearance from plasma of VLDL and LDL and reduces the formation of LDL from VLDL.
Conclusion: Weight loss achieved through healthful diets reduces apoC-III and atherogenic LDL with apoC-III but increases apoE in apoB-lipoproteins regardless of macronutrient emphasis. These effects on lipoprotein subfractions represent a novel mechanism by which weight loss may reduce cardiovascular disease risk.
- © 2013 by American Heart Association, Inc.