Acute effects of high-fat meals enriched with walnuts or olive oil on postprandial endothelial function.
OBJECTIVE
We sought to investigate whether the addition of walnuts or olive oil to a fatty meal have differential effects on postprandial vasoactivity, lipoproteins, markers of oxidation and endothelial activation, and plasma asymmetric dimethylarginine (ADMA).


BACKGROUND
Compared with a Mediterranean diet, a walnut diet has been shown to improve endothelial function in hypercholesterolemic patients. We hypothesized that walnuts would reverse postprandial endothelial dysfunction associated with consumption of a fatty meal.


METHODS
We randomized in a crossover design 12 healthy subjects and 12 patients with hypercholesterolemia to 2 high-fat meal sequences to which 25 g olive oil or 40 g walnuts had been added. Both test meals contained 80 g fat and 35% saturated fatty acids, and consumption of each meal was separated by 1 week. Venipunctures and ultrasound measurements of brachial artery endothelial function were performed after fasting and 4 h after test meals.


RESULTS
In both study groups, flow-mediated dilation (FMD) was worse after the olive oil meal than after the walnut meal (p = 0.006, time-period interaction). Fasting, but not postprandial, triglyceride concentrations correlated inversely with FMD (r = -0.324; p = 0.024). Flow-independent dilation and plasma ADMA concentrations were unchanged, and the concentration of oxidized low-density lipoproteins decreased (p = 0.051) after either meal. The plasma concentrations of soluble inflammatory cytokines and adhesion molecules decreased (p < 0.01) independently of meal type, except for E-selectin, which decreased more (p = 0.033) after the walnut meal.


CONCLUSIONS
Adding walnuts to a high-fat meal acutely improves FMD independently of changes in oxidation, inflammation, or ADMA. Both walnuts and olive oil preserve the protective phenotype of endothelial cells.
Cortés
Berenice
B
Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
Núñez
Isabel
I
Cofán
Montserrat
M
Gilabert
Rosa
R
Pérez-Heras
Ana
A
Casals
Elena
E
Deulofeu
Ramón
R
Ros
Emilio
E
D001916:Brachial Artery / Q000503:physiopathology; D015815:Cell Adhesion Molecules / Q000097:blood; D018592:Cross-Over Studies; D016207:Cytokines / Q000097:blood; D004041:Dietary Fats / Q000008:administration & dosage* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019040:E-Selectin / Q000097:blood; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005215:Fasting / Q000097:blood; D006801:Humans; D006937:Hypercholesterolemia / Q000503:physiopathology*; D018836:Inflammation Mediators / Q000097:blood; D031324:Juglans; D008077:Lipoproteins, LDL / Q000097:blood; D009754:Nuts; D000069463:Olive Oil; D009994:Osmolar Concentration; D010938:Plant Oils; D019518:Postprandial Period; D012039:Regional Blood Flow; D014280:Triglycerides / Q000097:blood; D014664:Vasodilation
D015815:Cell Adhesion Molecules; D016207:Cytokines; D004041:Dietary Fats; D019040:E-Selectin; D018836:Inflammation Mediators; D008077:Lipoproteins, LDL; D000069463:Olive Oil; D010938:Plant Oils; D014280:Triglycerides; C099252:oxidized low density lipoprotein