Effects of walnut consumption on endothelial function in type 2 diabetic subjects: a randomized controlled crossover trial.
OBJECTIVE
To determine the effects of daily walnut consumption on endothelial function, cardiovascular biomarkers, and anthropometric measures in type 2 diabetic individuals.


METHODS
This study was a randomized, controlled, single-blind, crossover trial. Twenty-four participants with type 2 diabetes (mean age 58 years; 14 women and 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) walnuts/day and an ad libitum diet without walnuts for 8 weeks. Subjects underwent endothelial function testing (measured as flow-mediated dilatation [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, A1C, fasting glucose, insulin sensitivity, and anthropometric measures.


RESULTS
Endothelial function significantly improved after consumption of a walnut-enriched ad libitum diet compared with that after consumption of 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 and lowered serum total cholesterol and LDL 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), although these changes were not significant compared with those for an ad libitum diet without walnuts. There were no significant changes in anthropometric measures, plasma A1C, and insulin sensitivity.


CONCLUSIONS
A walnut-enriched ad libitum diet improves endothelium-dependent vasodilatation in type 2 diabetic individuals, suggesting a potential reduction in overall cardiac risk.
Ma
Yingying
Y
Yale University School of Medicine, Derby, Connecticut, USA.
Njike
Valentine Yanchou
VY
Millet
John
J
Dutta
Suparna
S
Doughty
Kim
K
Treu
Judith A
JA
Katz
David L
DL
D000328:Adult; D000368:Aged; D001916:Brachial Artery / Q000503:physiopathology; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000502:physiology*; D005215:Fasting; D005260:Female; D007839:Functional Laterality; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D007328:Insulin / Q000097:blood; D031324:Juglans; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D016037:Single-Blind Method; D014664:Vasodilation
D006442:Glycated Hemoglobin; D007328:Insulin; D008055:Lipids