Pass the Nuts, Please

Traditional holiday meals in earlier times always ended (after the Christmas pudding) with fruit and nuts, maybe accompanied by port. That’s a fairly healthy way to end a meal, you might say. Fruit is on everyone’s health list, and port has plenty of resveratrol (the ‘good’ component of red wine). And now nuts – specifically, walnuts - are being touted as life-savers.

Spanish researchers examined the effect of a single meal, containing either walnuts or olive oil, on blood flow in the brachial artery (the main arm artery). The blood flow is related to the elasticity of the artery wall, which in turn depends on the degree of atherosclerosis present. They used 12 healthy and 12 patients with high blood cholesterol for their study; the test meal was high in fat, and contained 40 g walnuts or 25 g olive oil.

The blood flow-mediated dilatation of the artery in the high-cholesterol patients was increased by 24% after the walnut-enriched meal, but was decreased by 36% after the olive-oil enriched meal. In the healthy volunteers, the flow was unchanged after the walnut meal, but impaired by 17% after the olive oil.

Before you start gulping a handful of walnuts after every naughty meal, take note that this study was sponsored by the California Walnut Board, and you should therefore take your nuts with a pinch of salt. Confirmatory studies will doubtless follow, to see if this is a walnut effect, an ‘any-nut’ effect, or an irreproducible result.