Ma, Y., V.Y. Njike, J. Millet, S. Dutta, K. Doughty, J.A. Treu, D.L. Katz, 2010. Effects of walnut consumption on endothelial function in type 2 diabetics: a randomized, controlled, cross-over trial. Diabetes Care. 33(2):227-32.
Objective: To determine the effects of daily walnut consumption on endothelial function, cardiovascular biomarkers, and anthropometric measures in type 2 diabetics. Methods: This study was a randomized, controlled, single-blind, cross-over trial. Twenty-four participants with type 2 diabetes (mean age 58 years; 14 women, 10 men) were randomly assigned to one of the two possible sequence permutations to receive an ad libitum diet enriched with 56 g (366 kcal) of walnuts per day and an ad libitum diet without walnuts for 8 weeks. Subjects underwent endothelial function testing (measured as flow-mediated dilatation or FMD) and assessment of cardiovascular biomarkers before and after each 8-week treatment phase. The primary outcome measure was the change in FMD after 8 weeks. Secondary outcome measures included changes in plasma lipids, HbA1c, fasting glucose, insulin sensitivity, and anthropometric measures. Results: Endothelial function significantly improved after consumption of a walnut-enriched ad libitum diet compared to an ad libitum diet without walnuts (2.2 ± 1.7 % vs. 1.2 ± 1.6 %; p=0.04). The walnut-enriched diet increased fasting serum glucose, lowered serum total cholesterol and low-density lipoprotein cholesterol from baseline (10.0 ± 20.5 mg/dL; p=0.04, -9.7 ± 14.5 mg/dL; p<0.01; and -7.7 ± 10 mg/dL; p<0.01 respectively), though these changes were not significant when compared to an ad libitum diet without walnuts. There were no significant changes in anthropometric measures, plasma HbA1c, and insulin sensitivity. Conclusions: A walnut-enriched ad libitum diet improves endothelium-dependent vasodilatation in type 2 diabetics, suggesting a potential reduction in overall cardiac ris