L-Phenylalanine is an essential Amino Acid, and is involved in the product of neurotransmitters and may help in the balancing of brain chemistry and improved cognitive function. It plays a role in learning and memory. Amino Acids are essential to health. Most form the small structural components of protein and are required for the synthesis of protein within the body. The primary function of most Amino Acids is to furnish the essential material for duplication of the genetic code, for cell division, and for the formation of muscles and connective tissue.