Walnuts and endothelial function in hypercholesterolemic subjects.

Hypercholesterolemic Subjects To the Editor: Ros et al1 recently reported that substituting walnuts for monounsaturated fat in a Mediterranean-type diet improves endothelial function in hypercholesterolemic subjects. The investigators explain that nuts contain sizable amounts of antioxidants, as well as L-arginine and -linolenic acid, which might also confer additional antiatherogenic properties. I should emphasize, however, that a walnut-enriched diet contains high magnesium levels (ie, 169 elements of magnesium per 100 g of nut). We previously demonstrated2 that magnesium supplementation in patients with coronary artery disease (CAD) was associated with significant improvement in brachial artery endothelial function and exercise tolerance. Our group also demonstrated that oral magnesium supplementation inhibits platelet-dependent thrombosis in CAD patients, independent of platelet aggregation or P-selectin expression, and was evident despite aspirin therapy.3 Magnesium is also an antioxidant4 and therefore may additively alter lipid profile and improve endothelial function. Therefore, the magnesium found in walnuts may explain some of the beneficial effects described by Ros et al.1