👉 Cystine is a type of amino acid that is found in the body's urine. It is a byproduct of protein metabolism and is important for maintaining proper function of various organs, including the kidneys. In humans, cystine plays a crucial role in regulating blood pressure and in the production of proteins in the kidney. It also plays a role in the formation of certain hormones and enzymes, such as those involved in the synthesis of uric acid. While cystine is not essential for human health