Amino Acids are most commonly known as the building blocks of proteins and are compounds which play many essential roles in the body ranging from the building of proteins to the synthesis of hormones and neurotransmitters. Essential Amino Acids are the 9 amino acids that the body cannot synthesize itself and must be obtained through dietary sources. Double Wood s Essential Amino Acid supplement contains all 9 of the essential amino acids: L-Leucine, L-Lysine, L-Threonine, L-Valine, L-Isoleucine, L-Phenylalanine, L-Histidine, L-Tryptophan, L-Methionine.