Nature's Plus is the first to offer a 100% pure L-Tyrosine capsule together with its synergistic partner, Vitamin B-6. Vitamin B-6 is an integral cofactor in the body's utilization of L-Tyrosine. Amino acids, the famed building blocks of protein, are essential to the formation of muscle tissue and mass. They have widespread involvement in a range of bodily functions, including efficient brain function and the manufacture of energy.