Choline is a water-soluble essential nutrient. It is usually grouped within the B-complex vitamins. Choline generally refers to the various quaternary ammonium salts containing the N,N,N-trimethylethanolammonium cation. (X− on the right denotes an undefined counteranion).
The cation appears in the head groups of phosphatidylcholine and sphingomyelin, two classes of phospholipid that are abundant in cell membranes. Choline is the precursor molecule for the neurotransmitter acetylcholine which is involved in many functions including memory and muscle control.
Choline must be consumed through the diet in order for the body to remain healthy. It is used in the synthesis of the constructional components in the body's cell membranes. Despite the perceived benefits of choline, dietary recommendations have discouraged people from eating certain high choline foods, such as egg and fatty meats. The 2005 National Health and Nutrition Examination Survey stated that only 2% of postmenopausal women consume the recommended intake for choline.