Vitamin B4 (choline)

Choline was first discovered in 1849 by A. Steker in bile. However, it was isolated in pure form only in 1862, and then it was first named. The physiological role of choline began to be paid attention to after the research of K. Dyakonov, who showed that choline is part of lecithin as its constant structural component. The special position of lecithin as a food factor is associated not with its phosphorus-containing component, but with choline. Exclusion of choline from food leads to the development of fatty liver. Including it in food can prevent and eliminate this type of obesity. In this regard, choline was classified as an essential food factor.

Physicochemical properties of choline

Choline is an amino-ethyl alcohol containing three methyl groups at the nitrogen atoms. The hydroxyl group at the nitrogen is in an ionized state, making choline a strong base.

It is a colourless compound that crystallises with difficulty due to its high hygroscopicity. It is usually a viscous syrupy liquid. It is highly soluble in water and alcohol, but insoluble in ether. Choline is relatively stable, and high temperatures (up to 180° C) do not destroy it. When treated with hot alkali, it can be destroyed to form trimethylamine. Choline has the ability to form salts with many organic and inorganic acids. Its hydrochloride salt is the most common.

Being a component of phospholipids, choline is a part of almost all cells of the body. In the animal organism it is found not only in lecithin, but also in a free state. In the blood there is about 35 mg% of free choline, with most of it in the plasma and only a small amount in the cells. The content of choline in human blood is subject to seasonal fluctuations: the lowest amount is usually found in July, and the highest in February and March. The content of choline in human blood is 6.1-13.1 μmol / l. In women, at different periods of the menstrual cycle, the highest amount is around day 14, and the lowest around day 26. Choline is excreted in large quantities with menstrual blood. Choline is also found in the cerebrospinal fluid. The concentration of total and free choline is 104 - 423 and 77 - 216 ng / ml, respectively. There is a lot of free and bound choline in human seminal fluid.

Choline metabolism

Choline comes with food. It is partially destroyed by intestinal microflora (with the formation of trimethylamine). With a high choline content in the diet, it is absorbed by diffusion, with a low content - by active transport.

From the intestines, phosphocholine (and partially free choline) as part of lipoproteins is carried by the blood to tissues, where it is included in metabolism.

Choline introduced into the body is excreted with urine, bile and sweat. 0.7 - 1.5% of choline per day is excreted with urine. In children under 6 months - 2 g per day. About 0.01 of the total amount of choline taken is excreted with sweat. In case of kidney dysfunction, choline and its decay products are excreted slowly and contribute to an increase in existing azotemia. Choline is not excreted with feces, except in cases of diarrhea.

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Biological functions of choline

Information about the mechanism of action of choline indicates that it is primarily a component of the biologically active acetylcholine, a mediator.

In addition, choline takes part in transmethylation reactions in the biosynthesis of methionine, purine and pyrimidine nucleotides, phospholipids, etc. Phosphocholine is also used to synthesize phosphatidylcholine (lecithin). In addition, it takes part in the synthesis of another lipid - sphingomyelin, which is formed by transferring choline from phosphatidylcholine to ceramide.

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What foods contain holi?

Choline is found in many food products. Plant products contain less choline than animal products. In the latter, the choline content is proportional to the phospholipid content. The best source of choline among animal products is egg yolk. Choline is also found in the liver, brain and pancreas. Among plant products, the best source is green leaves and legumes, in cereals, in the germ part of the grain. A certain amount of choline is lost during cooking. When boiling meat and liver, they make up 18%, when baking the product, the loss is insignificant.

Choline requirement

There is no precise data on the human need for choline. The usual diet provides 1.5 to 4.0 g of choline per day. Sufficient supply of food with protein, vitamin B12, folic acid, significantly reduces the need of the animal organism for choline. A young organism is more sensitive to choline deficiency than an adult.

Choline deficiency

With a normal diet, there is no reason to believe that a person may develop primary choline deficiency. However, the development of secondary choline deficiency is possible. More often, it occurs with a lack of protein in the diet. Protein deficiency can be not only exogenous in nature, associated with a protein deficiency in the diet, but also endogenous in origin, when, as a result of certain pathological processes, the absorption and assimilation of protein in the body is disrupted. Liver pathology as a result of choline deficiency is possible with parenteral nutrition.