Choline is an organic compound, classified as a water-soluble essential nutrient and usually grouped within the Vitamin B complex.
It is found in the lipids that make up cell membranes and in the neurotransmitter acetylcholine.
Adequate intakes (AI) for this micronutrient of between 425 to 550 milligrams daily, for adults, have been established by the Food and Nutrition Board of the Institute of Medicine of the National Academy of Sciences.
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, trimethylglycine (betaine) that participates in the S-adenosylmethionine synthesis pathways.
When choline is metabolized by the body, it may form trimethylamine, a compound with a fishy odor. Hence, when large amounts of choline are taken the person may suffer from a fishy body odor.
It is well established that supplements of methyl group transfer vitamins including B6, B12 and folate- reduce homocysteine and prevent heart disease. Choline is a necessary source of methyl groups for methyl group transfer.
The foods richest in phosphatidylcholine — the major delivery form of choline — are egg yolks, soy and cooked beef, chicken, veal and turkey livers. In 2004, the USDA released its first database of the choline content in common foods.