A walnut diet improves endothelial function in hypercholesterolemic subjects: a randomized crossover trial.
BACKGROUND
Epidemiological studies suggest that nut intake decreases coronary artery disease (CAD) risk. Nuts have a cholesterol-lowering effect that partly explains this benefit. Endothelial dysfunction is associated with CAD and its risk factors and is reversed by antioxidants and marine n-3 fatty acids. Walnuts are a rich source of both antioxidants and alpha-linolenic acid, a plant n-3 fatty acid.


RESULTS
To test the hypothesis that walnut intake will reverse endothelial dysfunction, we randomized in a crossover design 21 hypercholesterolemic men and women to a cholesterol-lowering Mediterranean diet and a diet of similar energy and fat content in which walnuts replaced approximately 32% of the energy from monounsaturated fat. Participants followed each diet for 4 weeks. After each intervention, we obtained fasting blood and performed ultrasound measurements of brachial artery vasomotor function. Eighteen subjects completing the protocol had suitable ultrasound studies. Compared with the Mediterranean diet, the walnut diet improved endothelium-dependent vasodilation and reduced levels of vascular cell adhesion molecule-1 (P<0.05 for both). Endothelium-independent vasodilation and levels of intercellular adhesion molecule-1, C-reactive protein, homocysteine, and oxidation biomarkers were similar after each diet. The walnut diet significantly reduced total cholesterol (-4.4+/-7.4%) and LDL cholesterol (-6.4+/-10.0%) (P<0.05 for both). Cholesterol reductions correlated with increases of both dietary alpha-linolenic acid and LDL gamma-tocopherol content, and changes of endothelium-dependent vasodilation correlated with those of cholesterol-to-HDL ratios (P<0.05 for all).


CONCLUSIONS
Substituting walnuts for monounsaturated fat in a Mediterranean diet improves endothelium-dependent vasodilation in hypercholesterolemic subjects. This finding might explain the cardioprotective effect of nut intake beyond cholesterol lowering.
Ros
Emilio
E
Lipid Clinic at the Endocrinology and Nutrition Service, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clínic, Barcelona, Spain. eros@clinic.ub.es
Núñez
Isabel
I
Pérez-Heras
Ana
A
Serra
Mercè
M
Gilabert
Rosa
R
Casals
Elena
E
Deulofeu
Ramón
R
D000328:Adult; D000368:Aged; D001120:Arginine / Q000097:blood; D001916:Brachial Artery / Q000000981:diagnostic imaging; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL / Q000097:blood; D018592:Cross-Over Studies; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000178:diet therapy*; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D009754:Nuts / Q000737:chemistry; D016896:Treatment Outcome; D014463:Ultrasonography; D019010:Vascular Cell Adhesion Molecule-1 / Q000097:blood; D014664:Vasodilation / Q000187:drug effects*; D017962:alpha-Linolenic Acid / Q000032:analysis; D024504:gamma-Tocopherol / Q000032:analysis
D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D004041:Dietary Fats; D008055:Lipids; D019010:Vascular Cell Adhesion Molecule-1; D017962:alpha-Linolenic Acid; D024504:gamma-Tocopherol; D001120:Arginine; D002784:Cholesterol