L-Arginine is a substance produced by the body in limited quantities which is important in maintaining good oxygen flow throughout the body, in manufacturing Creatine (an exercise stimulant and energy creator), and in maintaining good functioning of the liver and kidneys. The HCL is added to maintain a neutral pH so that the resulting concoction creates less stomach issues than standard Arginine base, which has been linked to a few cases of stomach upset. L-Arginine is a type of amino acid that works to maintain the integrity of the skin, joints, liver, and muscles. It also helps in maintaining good levels of blood sugar, hormones, and keeps the immune system functioning well.