Choline is an organic compound, classified as a water-soluble essential nutrient and usually grouped within the Vitamin B complex. This natural amine 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.

History

Choline was discovered by Andreas Strecker in 1864 and chemically synthesized in 1866. In 1998 choline was classified as an essential nutrient by the Food and Nutrition Board of the Institute of Medicine (U.S.A.).

Chemistry

Choline is a quaternary saturated amine with the chemical formula (CH₃)₃N⁺CH₂CH₂OHX⁻, where X⁻ is a counterion such as chloride (see choline chloride), hydroxide or tartrate. Choline chloride, in mixture with urea is used as a solvent ( DES ) and the salicylate salt is used topically for pain relief of aphthous ulcers.

Physiology

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 as a supplement

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.

Choline supplements are often taken as a form of 'smart drug' or nootropic, due to 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, intelligence and mood are mediated at least in part by acetylcholine metabolism in the brain. The compound's quaternary amine renders its lipid insoluble which might suggest it would be unable to cross the blood-brain barrier. However, despite choline's lipid insolubility, a choline transporter exists that allows transport across the blood-brain barrier. The efficacy of these supplements in enhancing cognitive abilities is a topic of continuing debate.