Choline is an essential water soluble nutrient that is often categorized as a B vitamin. Choline is a component of phosphatidylcholine and other phospholipids, which are critical for healthy cell membranes. It is also a precursor of acetylcholine, a neurotransmitter that performs many functions related to muscle control and memory. In addition, choline contributes to normal lipid metabolism, maintenance of normal liver function, and normal homocysteine metabolism.