Sulfur amino acids are a group of essential amino acids that contain sulfur in their chemical structure. The two primary sulfur amino acids are methionine and cysteine. These amino acids play crucial roles in protein synthesis, metabolism, and the production of important molecules like glutathione, which helps protect cells from oxidative stress. Methionine is an essential amino acid, meaning it must be obtained through diet, while cysteine can be synthesized in the body from methionine. Both are vital for various biological processes, including the formation of proteins, the regulation of gene expression, and the detoxification of harmful substances.