Vitamin B4 (choline)

Choline was first discovered in 1849 by A. Steker in bile. However, in its pure form, it was isolated only in 1862 and at the same time received its first name. The physiological role of choline began to be paid attention after K. Dyakonov's studies, which showed that choline is a part of lecithin as its permanent structural component. The special position of lecithin as a food factor is associated not with the phosphorus-containing component, but with choline. The exclusion of choline from food leads to the development of obesity of the liver. Incorporating it into food can prevent and eliminate this type of obesity. In this regard, choline was attributed to the number of irreplaceable nutritional factors.

Physico-chemical properties of choline

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

This is a colorless compound, which is difficult to crystallize due to high hygroscopicity. Usually it is a viscous syrupy liquid. It is readily soluble in water and alcohol, but insoluble in ether. Choline is relatively stable, and a high temperature (up to 180 ° C) does not destroy it. When treated with hot alkali, it can decompose to form trimethylamine. Choline has the ability to form salts with many organic and inorganic acids. Its most common is the hydrochloride salt.

Being an integral part of phospholipids, choline is almost a part of all cells of the body. In the animal body, it is found not only in the composition of lecithin, but also in the free state. In the blood of free choline contains about 35 mg%, with most of it in the plasma and only a small amount in the cells. The content of choline in the human blood is subject to seasonal fluctuations: the smallest 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 in different periods of the menstrual cycle, the greatest number is about 14 days, and the smallest about 26 days. Choline in large quantities stand out with menstrual blood. Choline is found in spinal fluid. The concentration of total and free choline is 104 - 423 and 77 - 216 ng / ml, respectively. Free and bound choline is abundant in the human seminal fluid.

Choline metabolism

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

From the intestine, phosphocholine (and partially free choline) in the lipoproteins with blood is carried to the tissues, where it is included in the metabolism.

Introduced into the body of choline, is excreted in the urine, bile and sweat. With urine, 0.7 - 1.5% choline per day is excreted. In children up to 6 months, 2 grams per day. After that, about 0.01 of the total amount of choline taken is output. If the kidney function is impaired, choline and its decay products are slowly withdrawn and contribute to an increase in the already existing azotemia. With feces, choline is not secreted, except in cases of diarrhea.

[1], [2], [3], [4], [5], [6], [7], [8], [9]

Biological functions of choline

Information on the mechanism of action of choline suggests that it is primarily an integral part of biologically active acetylcholine - a mediator.

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

[10], [11], [12], [13], [14], [15], [16]

Which products contain holi?

Choline is a part of many food products. Vegetable products contain less choline than products of animal origin. In the latter, the content of choline is proportional to the content of phospholipids in them. The best source of choline among products of animal origin is the egg yolk. Choline is also found in the liver, brain and pancreas. Of the plant products, its best source is green leaves and legumes, in cereals, in the germinal part of the grain. In the process of cooking, a certain amount of choline is lost. When cooking meat and liver, they are 18%, when baking the product, the losses are insignificant.

The need for choline

There is no exact data on the need of a person in choline. The usual food ration provides a day from 1.5 to 4.0 g of choline. Sufficient food supply with protein, vitamin B12, folic acid, significantly reduces the need of the animal body in choline. A young organism is more sensitive to the lack of choline than an adult.

Insufficiency of choline

With the usual composition of food, there is no reason to believe that a person may experience primary cholin insufficiency. However, the development of secondary choline insufficiency is possible. It often occurs when there is a lack of protein in the food. Protein deficiency can be not only exogenous in nature, associated with protein deficiency in nutrition, but also in endogenous origin, when as a result of various pathological processes, absorption and assimilation of protein are disturbed in the body. The pathology of the liver as a result of a deficiency of choline is possible with parenteral nutrition.