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

Abstract

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.

FIGURE 1

Participant flow in the Dietary Modification Trial of the Women's Health Initiative.

FIGURE 2

Six-year mean (±SE) changes in triglyceride and HDL-cholesterol (HDL-C) concentrations (A) and in non-HDL-cholesterol (Non-HDL-C) and LDL-cholesterol (LDL-C) concentrations (B) by randomization group. Significant differences in changes in HDL cholesterol at year 1 (P < 0.01) and in LDL cholesterol at year 3 (P < 0.05) were observed between women in the intervention and comparison groups of the Women's Health Initiative Dietary Modification Trial (DM-I and DM-C, respectively).

FIGURE 3

Mean differences in triglyceride concentrations at year 1 (adjusted for baseline triglyceride concentrations) in the intervention and comparison groups of the Women's Health Initiative Dietary Modification Trial, stratified by race-ethnicity and baseline diabetes.