L-Proline is one of the twenty amino acids used as protein components in living organisms. It is the primary amino acid found in cartilage and is important for maintaining youthful skin as well as repairing muscle, connective tissue and skin damage. It is also essential for the immune system and the necessary balance of this formula. It is an essential component of collagen. L-Proline is extremely important for the proper functioning of joints and tendons and also helps maintain and strengthen the heart muscle.