Low-fat dietary pattern and lipoprotein risk factors: the Women's Health Initiative Dietary Modification Trial.

BACKGROUND The Women's Health Initiative Dietary Modification Trial tested the effects on chronic disease of a dietary pattern lower in fat and higher in vegetables, fruit, and grains. OBJECTIVE The objective was to evaluate the effects of dietary carbohydrate changes on lipids and lipoprotein composition. DESIGN Postmenopausal women were randomly assigned to an intervention or a comparison group for a mean of 8.1 y. Lipoprotein analyses and subclasses were based on subsamples of 2730 and 209 participants, respectively. RESULTS At year 6, the total reported fat intake was 7.8% lower and carbohydrate intake was 7.6% higher in the intervention group than in the comparison group. Triglyceride change between groups differed by 2.3, 3.8, and -0.8 mg/dL at 1, 3, and 6 y, respectively, and HDL-cholesterol change differed by -1.6, -0.7, and -1.0 mg/dL at 1, 3, and 6 y, respectively. Changes did not differ by age, ethnicity, or obesity. In diabetic intervention women who were white, the triglyceride difference between the intervention and comparison groups was 33.8 mg/dL, whereas in black women with diabetes (n = 50 in the intervention group; n = 83 in the comparison group), the triglyceride difference was 6.4 mg/dL (P for 3-factor interaction = 0.049). No significant changes were observed in apolipoprotein or lipoprotein particles. Reductions in LDL cholesterol varied by quartile of reported lowering of saturated or trans fat. CONCLUSIONS The replacement of 7-8% of fat intake with complex carbohydrates over 6 y was not associated with clinically adverse effects on triglycerides, HDL cholesterol, or lipoprotein subclasses. Diabetic white women with higher triglyceride concentrations may have greater increases in triglycerides.