A Healthier Heart L-arginine is an amino acid with many important health benefits, especially in the cardiovascular system. Its abilities to block plaque formation and blood clots have shown benefits in arterial hypertension, peripheral vascular disease and angina. Arginine reduces platelet aggregation and blood viscosity and improves blood flow. In nonacidic and high oxygen conditions, it is a precursor for the synthesis of nitric oxide, a potent blood vessel dilator, which also acts as an antioxidant. Arginine has also been shown to improve the body’s capacity for exercise.