Essential amino acids are a group of nine amino acids that are essential for human health and cannot be produced by the body. Valine, Lysine, Leucine, and Arginine are all essential amino acids. Valine is a branched-chain amino acid with six letters, Lysine is an essential amino acid with six letters, Leucine is an essential branched-chain amino acid with seven letters, and Arginine is an essential amino acid with eight letters.