Choline functions in four broad categories in the animal body:
A) It is a metabolic essential for building and maintaining cell structure. As a phospholipid component, choline is a structural part of lecithin (phosphatidylcholine), of certain plasmologens and the sphingomyelins. Lecithin is a part of animal cell membranes and lipid transport moieties in cell plasma membranes.
B) Choline plays an essential role in fat metabolism in the liver. It prevents abnormal accumulation of fat (fatty livers) by promoting its transport as lecithin or by increasing the utilization of fatty acids in the liver itself.
C) Choline is essential for the formation of acetylcholine, a substance that makes possible the transmission of nerve impulses.
D) Choline is a source of labile methyl groups. Choline furnishes labile methyl groups for formation of methionine from homocystine and of creatine from guanidoacetic acid.
All naturally occurring fats contain some choline, and thus, it is supplied by all feeds that contain fat. Egg yolk, glandular meats, and brain are the richest animal sources; germ of cereals, legumes and oilseed meals are the best plant sources. Corn is low in choline, with wheat, barley and oats containing approximately twice as much choline as corn.
Little is known of the biological availability of choline in natural feedstuffs.