Choline was first isolated from ox bile (the Greek word is chole) by Andreas Strecker in 1862 and chemically synthesized in 1866. To fulfill the need of Choline in food and feed, Choline is synthesized as a natural identical product meeting several pharmacopoeia.But till mid 20th century people were not aware of the importance of enough Choline in the diet. In 1998 choline was classified as an essential nutrient by the Food and Nutrition Board of the Institute of Medicine (U.S.A.) and Adequate Intakes (AI) have been established.
Choline is a product becoming more and more in the focus as a food additive or as one of the components of pharmaceutical products. Therefore it is sometimes indicated as a nutraceutical (nutrition+pharmaceutical).
Choline is not truly a vitamin, because some mammals are able to synthesize Choline in the body. Neonates are not: they have a lack of Choline. Therefore the European Union obliged the use of Choline in milk replacers for babies!
Choline is indespensable for a number of fundamental processes in the body.
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.
Choline is ubiquitously distributed in foods where it is present in free and esterified forms. It is required to make the phospholipids phosphatidylcholine, lysophosphatidychloline, choline plasmalogen and sphingomyelin-essential components of all membranes. It is a precursor for the biosynthesis of the neurotransmitter acetylcholine and is also an important source of labile methyl group.
Metabolism of Choline
All tissues accumulate choline, but uptake by liver, kidney, mammary gland, placenta and brain are particular importance.
Choline as a supplement
Generally classed as a B-complex vitamin (sometimes referred to as vitamin B4)
Due to its role in lipid metabolism, Choline has also found its way into nutritional supplements which claim to reduce body fat; but there is little or no evidence to prove that it has any effect on reducing excess body fat or that taking high amounts of Choline will increase the rate at which fat is metabolised.
It is well established that supplements of methyl group transfer vitamins B6, B12, folic acid reduce the blood titer of homocysteine and prevent heart disease. Choline is a necessary source of methyl groups for methyl group transfer. Supplements of lecithin/choline by Central Soya scientists reduced heart disease in laboratory studies. The reduction in heart disease with lecithin supplements may however relate more to the cholesterol carrying capacity of lecithin than to the methyl group transfer role of choline.[specify]
Choline supplements are often taken as a form of 'smart drug' or nootropic, due to the the role that the neurotransmitter acetylcholine plays in various cognition systems within the brain. Choline is a chemical precursor or "building block" needed to produce the neurotransmitter acetylcholine. And research suggests that memory and intelligence are mediated at least in part by acetylcholine metabolism in the brain. The efficacy of these supplements in enhancing cognitive abilities is a topic of continuing debate.
It is an essential component for ensuring the proper functioning of the nervous system. Choline plays a vital role by:
- building and maintaining cell structures;
- forming acetylcholine the nerve transmitter. Reduction could result in memory disorder.
- in fat metabolism of the liver, to transport fat from the liver. This will reduce the risk of a fatty liver.
Choline also plays a nonessential role as a methyl donor used for transforming homocysteine into the essential amino acid methionine.
The Adequate Intake (AI) for choline is 550 mg/ day for men and 425 mg/ day for women. Choline is used in fat burner formula, as a food supplement in baby foods, a memory booster, and clinical nutrient in women.
Choline(trimethyl(2-hydroxyemethyl) ammonium hydroxide; hydroxide formula ((CH3)3N-CH2CH2OH) +OH-M 121) Usually occures as a colourless, syrupy liquid. This quaternery amine is a strong base (pkb=5) and absorbs carbon dioxide from the atmosphere. It crystallizes with difficulty and is very soluble in water alcohol, but insoluble in diethyl ether. While choline is stable in dilute solutions, at high concentrations and temperatures of 100º C it decomposes to ethylene glycol, polyethylene glycol and triethylamine.
Choline may be assayed by a wide variety of techniques.
The selection of the method should be based on the detection level required, the type of sample and equipment available.
Choline and Carcinogenesis
Choline-deficient animals are much more likely to develop liver cancer spontaneously, or in response to a carcinogen. Several mechanisms have been suggested for this cancerpromoting effect of choline deficiency.
Deficiency of Choline.
Consuming a Choline deficient diet results in a fatty liver, liver-cell death and could initiate liver cancer. Especially important is a sufficient rate of Choline in the diets for:
Infants and children, because they have an increased need for growth and brain development. Recently there has been published an article about the need of Choline for pregnant women to improve brain development in fetus.
Diabetics, who have reduced transport of Choline leading to memory dysfunction.
Athletes, having a reduced Choline level after training, therefore a reduced acetylCholine content and reduced performance.
Choline occurs in nature in the form of lecithin. Some producers use this lecithin in stead of Choline.
High doses of Choline(5-30 g per 70 kg of body weight) have been associated with 'fishy' body odour, vomiting, salivation, sweating and gastrointestinal distress. These side-effects are probably dose-dependent, and all but the fishy body odour can be prevented by prior administration of muscarinic receptor blocker as methscopolamine.