This is one of our most popular supplements. Formulated WITHOUT caffeine, its effects help your body function at peak performance during exercise. Nitric oxide is produced by nearly every type of cell in the human body and one of the most important molecules for blood vessel health. It’s a vasodilator, meaning it relaxes the inner muscles of your blood vessels, causing the vessels to widen. In this way, nitric oxide increases blood flow and lowers blood pressure. It also can decrease plaque growth and blood clotting.