Dietary interventions that lower lipoproteins containing apolipoprotein C-III are more effective in whites than in blacks: results of the OmniHeart trial

Abstract

Blacks have lower average triglyceride and LDL cholesterol concentrations than do whites but higher rates of coronary heart disease. Apolipoprotein (apo) C-III in VLDL and LDL stimulates atherogenic processes in vascular cells. In blacks, the concentration of lipoproteins with apo C-III is unknown, and the response to dietary strategies that lower triglyceride and apo C-III has not been investigated We compared the concentration of and dietary effects on apo C-III-containing lipoproteins in blacks and whites. In a randomized, 3-period feeding study [OmniHeart (Optimal Macronutrient Intake Trial to Prevent Heart Disease)], we measured lipoprotein concentrations in 89 blacks and 73 whites who consumed self-selected diets (baseline) and after 3 healthful diets emphasizing carbohydrate, unsaturated fat, or protein. Participants had prehypertension or hypertension, and 79% were overweight or obese. While consuming self-selected diets, blacks had lower apo C-III in total plasma, VLDL, and LDL than did whites. Unsaturated fat and protein diets lowered plasma apo C-III (16% and 18%, respectively) and triglyceride (12% and 21%, respectively) in whites but not in blacks, reducing racial differences. Most important, blacks had a lower concentration of atherogenic LDL with apo C-III at baseline and after study diets (34-41% lower, P < 0.02). The molar ratio of apo E to apo B was higher in blacks than in whites in total plasma and LDL at baseline and after the study diets. Blacks have lower concentrations of atherogenic lipoproteins that contain apo C-III than do whites when consuming diverse diets and an attenuated dietary response of triglyceride and apo C-III. Dietary efforts to lower triglyceride and apo C-III may be more effective in whites than in blacks. The OmniHeart Trial was registered at www.clinicaltrials.gov as NCT00051350.