Scientific Study

OBJECTIVE: The aim of this study was to examine the effect of a moderate-fat diet inclusive of walnuts on blood lipid profiles in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: This was a parallel randomized controlled trial comparing three dietary advice groups each with 30% energy as fat: low fat; modified low fat; and modified low fat inclusive of 30 g of walnuts per day. Fifty-eight men and women; mean age 59.3 +/- 8.1 years; started the trial. Dietary advice was given at baseline with monthly follow-up and fortnightly phone calls for support. Body weight; percent body fat; blood lipids; HbA1c; total antioxidant capacity; and erythrocyte fatty acid levels were measured at 0; 3; and 6 months. Data were assessed by repeated-measures ANOVA with an intention-to-treat model. RESULTS: The walnut group achieved a significantly greater increase in HDL cholesterol-to-total cholesterol ratio (P=0.049) and HDL (P=0.046) than the two other treatment groups. A 10% reduction in LDL cholesterol was also achieved in the walnut group; reflecting a significant effect by group (P=0.032) and time (P=0.036). There were no significant differences between groups for changes in body weight; percent body fat; total antioxidant capacity; or HbA1c levels. The higher dietary polyunsaturated fat-to-saturated fat ratio and intakes of omega-3 fatty acids in the walnut group were confirmed by erythrocyte biomarkers of dietary intake. CONCLUSIONS: Structured "whole of diet" advice that included 30 g of walnuts/day delivering substantial amounts of polyunsaturated fatty acid improved the lipid profile of patients with type 2 diabetes.