Twinlab L-Arginine Capsules contain 500 mg of L-Arginine. L-arginine is a free-form amino acid that is needed to create both creatine and urea, a waste product that is necessary for the removal of toxic ammonia from the body. While the body typically manufactures enough l-arginine, it is considered a semi-essential amino acid as supplementation is sometimes needed. Arginine is a precursor to nitric oxide, which causes relaxation of the blood vessels, and also plays a key role in the production of protein. Each capsule contains 500 mg of L-arginine. No tablet binders, coatings or added flavorings, salt, artificial sweeteners, colorings, preservatives or salicylates.