Cysteine

Cysteine, abbreviated as Cys, is a sulfur-containing non-essential amino acid. It is often used as a dough conditioner which also extends shelf life of baked goods. It is a known flavor enhancer and is also used in cosmetics and pharmaceuticals in the drug industry. This sulfer-containing amino acid is synthesized for industrial use. Studies show links to allergic reactions, toxicity, interference with certain medications, and even ethical concerns as some cysteine is derived from human hair and feathers.