Fatty acids are a class of compounds composed of carbon, hydrogen, and oxygen, which are the main components of neutral fats, phospholipids, and glycolipids. Fatty acid metabolism Fatty acids can be divided into Short-chain fatty acid according to different carbon chain lengths. The number of carbon atoms on the carbon chain is less than 6, also known as volatile fatty acids; Medium chain fatty acids refer to fatty acids with 6-12 carbon atoms on the carbon chain, mainly composed of octanoic acid (C8) and decanoic acid (C10); Long chain fatty acids have a carbon atom number greater than 12 on their carbon chain. Most foods contain long-chain fatty acids. According to the difference between saturated and unsaturated hydrocarbon chains, fatty acids can be divided into three categories: Saturated fat acids, which have no unsaturated bonds on hydrocarbon; Monounsaturated fatty acid has an unsaturated bond in its hydrocarbon chain; Polyunsaturated fatty acid has two or more unsaturated bonds in its hydrocarbon chain.