Effect of L-arginine supplementation on NO production in man

L-arginine is the substrate for the enzyme nitric oxide synthase (NOS), which is responsible for the production of nitric oxide (NO), an endogenous messenger molecule involved in many of the processes associated with the development of atherosclerosis. Acute and chronic administration of L-arginine has been shown to improve endothelial function in animal models of hypercholesterolemia and atherosclerosis. Therefore, numerous studies have been conducted to elucidate whether dietary L-arginine supplementation can augment NO production in humans and thereby improve vascular health. In this review, the results of studies of intravenous and oral L-arginine supplementation with a wide spectrum of doses, study duration, and surrogate parameters of endothelial function are summarized. The pharmacokinetics of L-arginine have been investigated; side effects are rare and mostly mild and dose-dependent. Several possible mechanisms of action of L-arginine are discussed. An evaluation of L-arginine as a therapeutic agent from the point of view of a clinical pharmacologist is given.