For many years, choline often was included in supplements as a “supposed” B-vitamin, but most nutrition experts claimed that choline was not a vitamin at all because liver synthesis could meet the requirements for choline. However, recent research demonstrates that humans consuming choline-deficient diets develop liver and kidney problems. Still, choline is not yet considered a B-vitamin. It does not have a coenzyme function and the amount of choline in the body is much greater than the amount of a typical B-vitamin.
CHOLINE IN FOODS
Choline is widely distributed in foods of animal origin, mostly in the form of phosphatidylcholine (lecithin) in cell membrane and blood lipoproteins. Milk, liver, eggs, and peanuts are rich sources. Lecithins are often added to food during processing, so this is yet another source. Data in the choline content of foods are still incomplete; however, nutrient data are increasing. Because choline is so widespread in the diet, a deficiency is unlikely.
CHOLINE NEEDS AND UPPER LIMIT
The Adequate Intake for choline for adult men is 550 mg/day; for adult women, it is 425 mg/day. Few data exist to asses whether a dietary supply is needed at all life stages. Although Adequate Intakes are set for choline, it may be that the choline requirement can be met by body synthesis at some or all stages of life. We also consume ample choline from food, at least 700 to 1000 mg/day, so there is no need to supplement a diet with choline.
The Upper Level for adults is 3.1 g/day. Very high doses of choline have been associated with low blood pressure, vomiting, salivation, sweating, and GI tract effects.
FUNCTIONS OF CHOLINE
Choline is a component of phospholipids, such as phosphatidylcholine (lecithin), a major component of cell membranes and blood lipoproteins. Choline also functions as a presurcor for acetylcholine, a neurotransmitter associated with attention, learning, memory, muscle control, and many other functions.
Liver export of VLDL is associated with the action of chiline, too. The methyl group of choline can be used to form methionine from homocysteine, and supplementation with choline in healthy men has shown to decrease homocysteine concentrations. Preliminary research suggest that high choline intakes are associated with lower plasma concentration of a compound (C-reactive protein) that indicated inflammation. /because inflammation increases the risk of cardiovascular disease, choline may offer protection against that disease.
When humans were fed choline-deficient total parenteral nutrition solutions, they developed fatty livers and liver damage. Based on these observations, plus laboratory anmal studies, choline has been deemed essential, at least in some life stages and health conditions.