“Melanosis” in the small and large intestine Melanosis Coli El Atlas Gastrointestinal gastrointestinalatlas.com Your body already makes a hormone that tells your skin to tan. Melanotan 2 is a synthetic peptide engineered to mimic that hormone but in a version that's more potent and longer lasting than 6 Things Your Poop Can Tell You About Your Health NYC Gastroenterologist Manhattan Gastroenterology