Tributyrin, also known as glyceryl tributyrate, is a triglyceride (fat) naturally present in butter. It is an ester composed of three butyric acid (butyrate) moieties and glycerol. It can be described as a liquid fat with an acrid taste. About 3 to 4% of butter is tributyrin, with butter being the richest known food source of tributyrin. It is a slowly converted precursor or prodrug of the short-chain fatty acid (SCFA) butyric acid, which is a major product of gut bacteria and hence "postbiotic".