Effects of walnut consumption on endothelial function in type 2 diabetic subjects: a randomized controlled crossover trial

Diabetes Care. 2010 Feb;33(2):227-32. doi: 10.2337/dc09-1156. Epub 2009 Oct 30.

Abstract

Objective: To determine the effects of daily walnut consumption on endothelial function, cardiovascular biomarkers, and anthropometric measures in type 2 diabetic individuals.

Research design and 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.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Brachial Artery / physiopathology
  • Cross-Over Studies
  • Diabetes Mellitus, Type 2 / physiopathology*
  • Endothelium, Vascular / physiology*
  • Fasting
  • Female
  • Functional Laterality
  • Glycated Hemoglobin A / metabolism
  • Humans
  • Hyperemia / physiopathology
  • Insulin / blood
  • Juglans*
  • Lipids / blood
  • Male
  • Middle Aged
  • Single-Blind Method
  • Vasodilation

Substances

  • Glycated Hemoglobin A
  • Insulin
  • Lipids