Vitamins (from lat. Vita – life + amines ) – a group of low molecular weight organic chemicals of various structures, necessary for the normal functioning of the body. The name vitamins is somewhat outdated. At the dawn of the era of the discovery of vitamins, it was believed that all of them contain a grouping (NH3), that is, from the point of view of chemical structure, they are amines. Later, a large group of chemicals of various structures, possessing the properties of vitamins, was discovered. The name of vitamins, yet stuck in scientific literature, and in everyday practice. Vitamins are substances that are absolutely necessary for normal metabolic processes in the body. The state of vitamin deficiency (one or more) is called Avitaminosis, and is characterized by a profound metabolic disorder (metabolism in the body). The human body is not able to synthesize vitamins (with the exception of nicotinic acid), just as other substances are synthesized (proteins, fats, carbohydrates). The main source of vitamins for humans are food; Some vitamins are synthesized by intestinal microflora. Insufficient intake of vitamins from food or intestinal dysbiosis (violation of the intestinal microflora), leads to the development of hypovitaminosis (low content of vitamins) or beriberi (the complete absence of one or several vitamins).
Unlike other vital substances (essential amino acids, polyunsaturated fatty acids), vitamins are not used by the body as a building material or energy resource. The role of vitamins in the body is that they are part of enzymes (enzymes) – biologically active molecules that catalyze various biochemical reactions. By themselves, most enzymes are protein molecules. Activation of the enzyme molecule is carried out by attaching to it a vitamin molecule (in this case, a coenzyme). Enzyme-coenzyme complex and has a catalytic activity. Such a complex will accelerate biochemical reactions thousands and millions of times.
Classification of vitamins
Today, more than 13 vitamins and vitamin-like substances are known. The most simple and common vitamin classification involves the division into two main groups, based on the principle of the solubility of vitamins in the water and fat environment. Knowledge of the solubility of vitamins is the basis of their proper use in the treatment and prevention of hypo-and avitaminosis.
So we distinguish two main groups of vitamins:
- Water-soluble vitamins – are a group of chemicals that are highly soluble in water. This group includes all the B vitamins, vitamin C, as well as folate, pantothenic acid, niacin, biotin.
- Fat-soluble vitamins are insoluble in water, but dissolve well in fats and other non-polar solvents (for example, alcohol). This group of vitamins include vitamins A, D, E, K.
Water soluble vitamins, as mentioned above, it is highly soluble in water. Due to this, they are well absorbed from the intestines and circulate freely in the blood. Fat-soluble vitamins are absorbed by their intestines, only in the presence of fats of vegetable or animal origin – this circumstance is important to consider when prescribing the treatment of beriberi: the vitamin is used along with a small amount of vegetable oil or animal fat.
The solubility of vitamins determines their prevalence in nature. This will be discussed below.
The prevalence of vitamins in nature. Sources of vitamins
Like all organic compounds, vitamins are synthesized by living organisms. The biochemical apparatus of human cells is unable to synthesize certain substances (in this case, vitamins), so in the process of evolution, the human body has adapted to extract vitamins from foods of different origin.
Vitamin C – is the most famous and affordable vitamin. It is found in large quantities in fresh vegetables and fruits. The most rich in vitamin C are wild rose and black currant. The daily dose of vitamin C necessary for an adult is contained in 30 g of black currant or 10 g of wild rose. Fresh herbs – parsley, dill also contain a sufficient amount of vitamin C. Smaller amounts of this vitamin are found in potatoes, fresh and sauerkraut. Contrary to the current conviction, citrus fruits contain an amount of vitamin C only twice as large as in potatoes, and 5-10 times less than in currants or dogrose.
Vitamin Bone (thiamin) – in sufficient quantities found in lean pork, liver and kidneys, as well as cereals (buckwheat, oatmeal). Fresh fruits and vegetables contain negligible amounts of vitamin Bone.
A reliable source of vitamin Bone is rye bread or bread made from fortified flour. Daily dose of vitamin bone necessary for an adult is contained in 800 g of rye bread or 400 g of pork.
Vitamin B2 (riboflavin) – found in large quantities in the liver and kidneys. In smaller, but sufficient quantities, this vitamin is contained in lactic acid products (cottage cheese, cheese). Meat, rye bread and cereals contain about the same amount of vitamin B2. The daily dose of riboflavin is contained in 200 g of liver or 500 g of cottage cheese or cheese.
Vitamin B3 (Pantothenic acid) – in small quantities found in fresh vegetables, fruits, rye and wheat bread. Eggs are more rich in Pantothenic acid. The greatest amount of this vitamin is found in the liver and kidneys. The daily need for pantothenic acid is covered 50-100 g of the liver.
Vitamin B6 (Riboxin) – is contained in large quantities in the liver (the daily dose is contained in 200g of the liver). Meat, cereals, and whole grain bread contain about the same amount of pyridoxine. Fruits and vegetables contain this vitamin in small quantities.
Vitamin PP (niacin) – the greatest amount of vitamin PP is found in cheese. Liver, kidneys and grains are also rich in this vitamin. Whole grain wheat bread and lean meat can serve as a reliable source of this vitamin. Vegetables and fruits contain vitamin PP in small quantities.
Vitamin B9 (folic acid) – the largest amount of folic acid is contained in the liver (the daily dose is contained in 100 g of the liver). Fresh herbs (parsley, dill) contain two times less folic acid than in the liver. Vegetables and fruits contain vitamin B9 in small quantities.
Vitamin B12 (cyanocobalamin) – is contained in sufficient quantities in the liver of meat and fish (the daily dose of vitamin is contained in 10-20 g of the liver). Lactic acid products and cheese can also serve as a source of this vitamin.
Vitamin H (biotin) – liver, eggs and meat are rich in these vitamins. Bread and cereals contain smaller amounts of biotin, and vegetables and fruits contain only minor amounts of it.
Vitamin A (retinol) – found in large quantities in beef and pork liver, as well as in cod liver. Butter and fat cottage cheese also contain sufficient amounts of this vitamin. A much more affordable source of vitamin A is fruits and vegetables. True, these products do not contain vitamin A itself, but its predecessor (B-carotene). Once in the body, B-carotene is converted to vitamin A through special biochemical reactions.
Vitamin E – found in large quantities in vegetable oils. The daily dose of this vitamin, necessary for an adult, is contained in 40 g of vegetable sunflower oil. Bread and cereals also contain an adequate amount of this vitamin.
Vitamin D – The daily dose of this vitamin is contained in a few milliliters of cod liver oil. Much less, but still enough of this vitamin is contained in eggs and butter. Vitamin D is synthesized from its precursors in the skin under the action of ultraviolet rays and in the kidneys.
Vitamin K – Like other vitamins is absolutely necessary for the normal functioning of the body. However, unlike other vitamins, its intake with food products is very insignificant. The main part of the necessary vitamin K for the body is synthesized by intestinal microflora. Absorption of this vitamin depends on the normal functioning of the intestine and the presence of lipids (fats) in the diet.
As it became apparent, the main source of most vitamins are animal products, especially liver and kidneys. This is explained by the high metabolic activity of these organs and the ability of vitamins to accumulate in them. However, vitamins such as A and C are mainly found in products of plant origin (fresh vegetables and fruits). Therefore, in order to ensure adequate intake of vitamins in the body you need to eat right. A balanced diet virtually eliminates the need to consume vitamins of synthetic origin.
Transformation of vitamins in the body
Most vitamins enter the body in an inactive state (provitamins). Through special biochemical transformations, provitamins are converted into active molecules that join the enzyme molecules. Some vitamins exist in several active states at once. Activation of vitamins occurs in various organs of the body. For example, B vitamins are activated in the liver. Vitamin D is activated in the skin (by ultraviolet rays and in the kidneys).
In addition to the transformation of provitamins into their active forms, the body is able to store some vitamins. To a greater extent this applies to fat-soluble vitamins (A, D, E, K), as well as folic acid and cyanocobalamin. Water-soluble vitamins accumulate in the body to a lesser extent, since due to the good solubility in water, they easily penetrate the renal barrier and are excreted in the urine.