The purpose of this article was to investigate the effects of dietary carbohydrate changes on lipids and lipoprotein composition. The data were obtained from the Women’s Health Initiative Dietary Modification Trial, an intervention designed to reduce total fat intake to 20% of energy and to increase vegetable and fruit intake to ≥5 servings/day as well as grain intake to ≥6 servings/day. The cohort included postmenopausal women who were randomly assigned to an intervention or a comparison group for a mean of 8.1 years. Analyses in a specific sample of postmenauposal women without severe hypertriglyceridemia at baseline revealed no clinically meaningful increases in triglycerides or decreases in HDL cholesterol associated with the increase in complex carbohydrate intake. However, diabetes status and race appeared to have a significant impact on the percentage of change in triglyceride levels between the intervention and control groups. The increase in triglycerides was more marked in diabetic white women with an average increase of 33.8 mg/dl (0.38 mmol/l) compared to 6.4 mg/dl (0.07 mmol/l) in black women with diabetes. Thus, these findings are in contrast with the prior literature since the intervention did not result in clinically meaningful increases in triglycerides or decreases in HDL cholesterol in the majority of women. In his comment, Willet WC qualified the findings of this study as remarkable considering the large literature that shows an increase in plasma fasting triglycerides and reduction of HDL cholesterol concentrations when replacing dietary fat with carbohydrates. However, he criticized the lack of compelling reasons to explain their findings and he proposed that it is probably the large increase in fruits and vegetables, whole grains and protein that counterbalanced the adverse effects of fat reduction. However, he suggested that the more plausible explanation is an overreporting of compliance with fat reduction by the women in the intervention group.
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