Doctor's Best L-Arginine HCL powder helps support athletic endurance and helps boost nitric oxide production. L-arginine also helps regulate blood pressure, helps improve cardiovascular health, Helps support a healthy immune system, Helps improve blood sugar regulation and helps support brain health. Nitric oxide is a powerful neurotransmitter that helps blood vessels relax and also improves circulation. As you age, nitric oxide production falls. By the time you're 40, studies show you're only making about half or less of what you Made when you were 20. This Doctor's Best Item contains no added colors, flavors, fillers, additives or unnecessary ingredients. Vegan, Non-GMO and gluten free.