Choline (trimethyl ethanolamine) is a quaternary saturated amine with the chemical formula

(CH₃)₃N⁺CH₂CH₂OH.

It was discovered by Strecker in 1862 and chemically synthesized in 1866. In 1998 choline was classified as an essential nutrient by the Food and Nutrition Board of the Institute of Medicine (U.S.A.) and Adequate Intakes (AI) have been established. Choline and its metabolites are needed for three main physiological purposes: structural integrity and signaling roles for cell membranes, cholinergic neurotransmission (acetylcholine synthesis), and as a major source for methyl-groups via its metabolite, betaine that participates in the S-adenosylmethionine synthesis pathways.