choline

Choline is an essential nutrient for humans, often grouped with B vitamins though it is not itself a vitamin. It exists in multiple forms, including free choline, phosphocholine, glycerophosphocholine, and phosphatidylcholine. Dietary choline is delivered mainly as phosphatidylcholine in lecithin-containing foods.

Choline serves several vital roles. It is a precursor of the neurotransmitter acetylcholine, a component of cell membranes (phosphatidylcholine and sphingomyelin), and a source of methyl groups via betaine for one-carbon metabolism. In the liver, choline supports assembly and export of very low-density lipoproteins (VLDL), helping prevent fat accumulation.

Because endogenous synthesis is limited, dietary intake is necessary. Adequate Intake (AI) values are about 550 mg/day for men and 425 mg/day for women; pregnancy and lactation increase needs to about 450 mg/day and 550 mg/day, respectively.

Food sources include eggs, liver, meat, fish, dairy, soybeans, and legumes; eggs are among the most concentrated sources. Deficiency is uncommon but can occur with very low intake and may affect liver function and fetal development. Excess choline from supplements can cause hypotension, sweating, diarrhea, or a fishy odor; the proposed upper intake level is 3,500 mg/day.