Abstract 10859: Walnut-enriched Diet Reduces Fasting Non-HDL-cholesterol in Healthy Caucasian Subjects

Abstract

Background: Epidemiological studies indicate that regular walnut consumption reduces the risk of coronary heart disease (CHD). We therefore evaluated the effect of walnut consumption on fasting and postprandial lipid and glucose metabolism in healthy subjects.

Methods: We included 40 healthy Caucasian men and postmenopausal women over the age of 50 (age 60±6 y, BMI 25.1±3.4 kg/m², 30 females) in a randomized, controlled, prospective, cross-over study (NCT01188902). Each subject followed a nut-free Western-type diet during a 2 week run-in period. Thereafter, subjects were randomized to 2 different diet phases, each lasting for 8 weeks (separated by a 2 week wash-out). One group (n=18) first followed a diet with walnuts (43 g of shelled walnuts/day) and then switched to an individually prescribed, nut-free Western-type (control) diet. The other group (n=22) followed the diets in reverse order. At the start and end of each diet phase, subjects received a standardized test meal (1100 kcal; 72% fat, 4% protein and 24% carbohydrate). Blood was drawn at 0 (fasting), 15, 30, 60, 120, 180, 240, 360, and 480 minutes. Total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglycerides (TG), VLDL-TG, glucose, insulin, HOMA and QUICKI were determined in fasting samples. Area under the curve (AUC) and incremental AUC were calculated for postprandial TG, VLDL-TG, chylomicron-TG, glucose and insulin.

Results: Compared with the control diet, the walnut diet resulted in a significant reduction in fasting non-HDL-C (walnut vs. control: -10.0±16.7 vs. -3.0±14 mg/dl; p = 0.032). Furthermore, TC (-7.9±16.9 vs. -1.8±15.2 mg/dl) showed a trend toward improvement (p = 0.08). HDL-C (2.1±7.3 vs. 1.2±7.6 mg/dl), LDL-C (-6.6±16.0 vs. -2.0±14.5 mg/dl) TG (-9.9±32.9 vs. -2.5±28.1 mg/dl), glucose (-0.7±6.0 vs. 1.3±9.1 mg/dl), insulin (0.5±2.6 vs. 1.6±3.4 µU/ml) and parameters of insulin resistance (HOMA, QUICKI) did not change significantly. Similarly, postprandial lipid and glucose metabolism did not change (neither AUC nor incremental AUC).

Conclusion: Daily consumption of 43 g of walnuts for 8 weeks significantly reduced non-HDL-C, which may explain the epidemiological observation that regular walnut consumption decreases the risk of CHD.