What is vitamin D responsible for? Vitamin D (Calciferol, viosterol, ergosterol)

Vitamin D, also called calciferol, is essential for people of all ages. The substance must be regularly supplied to the body in order for the skeleton to remain strong. Calciferol is extremely important for older people prone to pathologies of the musculoskeletal system. The vitamin is synthesized in the skin under the influence of sun radiation and also enters the body with food. Therefore, it is important for both adults and children to eat well and take frequent walks in the sun. If hypovitaminosis has developed, it is recommended to take vitamin D tablets.

The benefits of calciferol for the human body

Vitamin D performs several important functions in the human body:

• participates in the metabolism of calcium and phosphorus;
• moves minerals through the bloodstream into bone tissue;
• helps strengthen the immune system;
• regulates the absorption of mineral elements in the intestines;
• participates in the production of certain hormones.

There are several types of calciferol:

• D 2 – ergocalciferol;
• D 3 – cholecalciferol;
• D 5 – sitocalciferol;
• D 6 – stigmacalciferol.

Each of the above types of calciferol performs its own function in the human body. Vitamins D2 and D3 are especially important for humans. Other types of calciferol do not have a significant effect on the functioning of organs and systems.

Cholecalciferol is necessary for the complete absorption of calcium and phosphorus in the intestinal tract. Ergocalciferol optimizes the concentration of minerals in bone tissue. Vitamins D 2 and D 3 work in combination, so they both must enter the body in optimal quantities.

The effect of vitamin D on the female and male body

Vitamin D deficiency is the main enemy of female beauty. Calciferol maintains healthy bone structure, normalizes the functioning of the heart muscle and nerve fibers, regulates metabolism and blood clotting processes. If there is a lack of the substance, women's nails break, hair falls out profusely, gums bleed and teeth decay, limbs hurt, and fractures are often observed. The vitamin is also responsible for the absorption of phosphorus. With calciferol deficiency in women, due to a decrease in phosphorus in the body, skin rashes appear, health worsens, bone aches are felt, and metabolism is disrupted.

Men with vitamin D deficiency experience the same health problems as women. In addition, calciferol is important for maintaining normal hormonal levels in the male body. When there is a lack of the substance in men, the concentration of testosterone in the blood decreases, which increases the effect of female sex hormones on the body.

Daily intake of calciferol

The amount of vitamin consumed per day is determined by the age and physical condition of the person.

1. For adults, the norm is 400 IU per day.
2. For children and adolescents - from 400 to 600 IU.
3. For older people - from 600 to 800 IU.
4. For pregnant women - about 800 IU.

The best way to get vitamin D is to stand in direct sunlight. People who rarely go outside or live in northern regions have a significantly increased risk of developing hypovitaminosis D. The following categories of people need calciferol the most:

• inhabitants of high latitudes;
• residents of industrial areas where the air is heavily polluted with harmful substances;
• workers forced to work night shifts;
• vegetarians, adherents of strict diets;
• old men;
• dark-skinned people whose skin poorly receives solar radiation;
• people with reduced immunity or serious illnesses.

Indications for use of vitamin D

Vitamin D 3 is prescribed for the prevention and treatment of the following pathologies:

• rickets in children - a disease accompanied by thinning of bone tissue and skeletal deformation due to impaired calcium metabolism in the body;
• osteoporosis;
• deterioration in the functioning of the immune system, accompanied by respiratory dysfunction and chronic fatigue;
• oncology, if there is a predisposition to the development of malignant tumors;
• eczema, psoriasis and other skin diseases;
• hypocalcemia;
• renal tubular acidosis.

Vitamin D is also often prescribed as a restorative agent after long-term use of corticosteroid and anticonvulsant medications.

People living in the northern regions must periodically take calciferol preparations to prevent hypovitaminosis and other serious pathologies. For preventive purposes, the vitamin is prescribed at least once every three years.

Calciferol-rich foods

Solar radiation is the main, but not the only source of vitamin D. In the winter months, when there is a lack of sun, it is recommended to consume foods containing significant amounts of calciferol. The list of these products includes:

• fish fat;
• sea ​​fish;
• cheeses;
• butter;
• yolk;
• milk.

List of the best vitamin D tablets

Pharmacies sell large quantities of medicines based on vitamin D, both cheap and expensive. The price is determined by the form of release of the medicine, effectiveness, cost, and active substance. Thus, drugs based on vitamin D 3 are more expensive than drugs containing vitamin D 2.

1. .The best drug prescribed for frail and premature babies. The vitamin is given to infants in drop form. One drop contains 600 IU of calciferol. To give medicine to a child, the drop must be dissolved in a small amount of water. Aquadetrim is also prescribed to children and adolescents to prevent rickets.
2. Alpha D 3 -Teva. The medication is sold in capsules containing a solution of calciferol in oil. Intended for adults and children over 6 years old. The medication is taken daily, after meals you need to swallow 1 - 2 capsules with enough water. According to the instructions for use, the capsule should be swallowed without chewing.
3. Calcium-D 3 Nycomed. Chewable fruit tablets containing optimal amounts of cholecalciferol and calcium. The drug is intended for adults and children over 6 years of age. The recommended dosage is one tablet per day. The tablet is dissolved or chewed after eating.
4. Vitrum Calcium + Vitamin D 3. A complex drug, sold in tablet form, intended primarily for the prevention of osteoporosis. The optimal dosage is one tablet 2 times a day. The medication is taken before or during meals. It is better not to chew the tablet, but to swallow it whole.
5. Tevabon. The medication is sold in tablet and capsule form. Prescribed for the treatment of osteoporosis. The active ingredient is alfacalcidol. This is a synthetic analogue of vitamin D.
6. . A complex preparation based on calcium and cholecalciferol. Recommended for women as it eliminates brittle nails. It also improves the absorption of minerals in the body, prevents the development of osteoporosis, and normalizes blood clotting. You need to take 1-2 tablets a day, preferably chew them.
7. .Medicine in tablets, designed specifically for the elimination of osteoporosis and rapid regeneration of the skeleton after fractures. The components of the drug are cholecalciferol, calcium, copper, zinc, boron.
8. Calcemin. Dietary supplement containing calcium, cholecalciferol, zinc, manganese, copper. You need to take 1 tablet per day.
9. Natekal D 3. Chewable tablets based on calcium and vitamin D 3. The medication provides the body with an optimal amount of mineral and helps normalize hormonal levels. Daily dose – 1 – 2 tablets. Reception is carried out after meals.
10. Etalfa. A high-quality Danish drug is sold under this name. Available in drop and capsule form. The vitamin in capsules is dissolved in sesame oil. The medication is intended for the treatment of rickets and osteoporosis.
11. Van Alpha. A drug in tablet form based on alfacalcidol, an artificial analogue of vitamin D. It is prescribed for the treatment of rickets, strengthening the immune system, and normalizing the functioning of the thyroid gland.

Overdose and side effects

If a person is insensitive to the substance and takes the drug according to the instructions, then side effects are usually not observed. In rare cases, the following are noted:

• nausea;
• headache;
• diarrhea;
• deterioration of kidney function.

In case of sensitivity to the substance or overdose, the following symptoms are observed:

• sudden weight loss;
• nausea, vomiting;
• constipation;
• dehydration;
• calcification;
• increased blood pressure.

Contraindications to the use of vitamin D

Like all other vitamins, calciferol should not be taken in excess. It is forbidden to use vitamin D preparations for people who are sensitive to the active component, suffering from renal osteodystrophy and urolithiasis. People with tuberculosis, heart pathologies, kidney and liver disorders, stomach or duodenal ulcers should take the vitamin with extreme caution. Women during pregnancy and breastfeeding should definitely consult a medical specialist before taking a vitamin D supplement.

Sources

Food sources

• liver, yeast, fatty milk products (butter, cream, sour cream), egg yolk (mainly vitamin D2),
• fish oil, cod liver (vitamin D3).

Synthesis in skin

• is formed (vitamin D3) in the epidermis under ultraviolet irradiation (wavelength 290-315 nm) from 7-dehydrocholesterol.

Daily requirement

Vitamin D requirements can be measured in both micrograms and international units (IU) - 25 mcg of vitamin D corresponds to 1000 IU.

The physiological need for young children is 10 mcg, for older children and adults – 10-20 mcg, for people over 60 years old – 15 mcg.
The upper tolerable intake level is 50 mcg/day.

Exposure to UV radiation inducing skin redness in a minimal erythemal dose for 15-20 minutes can, depending on skin type, induce the production of up to 250 mcg of vitamin D (10,000 IU). However, the conversion of provitamin D3 to inactive metabolites lumisterol And tachisterol balances the skin biosynthesis of vitamin D3 via a feedback mechanism. This mechanism effectively prevents “overdose” of vitamin D3 during UV irradiation.

Vitamin D2, produced by plants and fungi and obtained from grains and dairy products, has been shown to be much more less effective compared to vitamin D3.

Dietary Guidelines for Americans (USA, 2015–2020) recommend daily intake of vitamin D: children and adults of both sexes from 0 to 70 years inclusive – 15 mg, elderly people, starting from the age of 71 – 20 mg

Structure

The vitamin comes in two forms - ergocalciferol And cholecalciferol. Chemically, ergocalciferol differs from cholecalciferol by the presence in the molecule of a double bond between C22 and C23 and a methyl group at C24.

The structure of two forms of vitamin D

After absorption in the intestines or after synthesis in the skin, vitamin D3 is transported to the liver by a specific protein. Here it is hydroxylated at C25 and transported by a transport protein to the kidneys, where it is hydroxylated again, this time at C1. The active form of the vitamin is formed - 1,25-dihydroxycholecalciferol or, in other words, calcitriol.

Structure of calcitriol

The hydroxylation reaction in the kidneys is stimulated by parathyroid hormone, prolactin, growth hormone and is suppressed by high concentrations of phosphates and calcium.

Biochemical functions

The most studied and well-known functions of the vitamin are:

1. Increase concentrations calcium And phosphates in blood plasma.

To achieve this, calcitriol induces synthesis in target cells calcium binding protein and components Ca 2+ -ATPases and as a result:

• increases the absorption of Ca 2+ ions into small intestine,
• stimulates the reabsorption of Ca 2+ ions and phosphate ions in proximal renal tubules.

2. Suppresses secretion parathyroidhormone through increasing the concentration of calcium in the blood, but enhances its effect on the reabsorption of calcium in the kidneys.

3. In bone tissue, the role of vitamin D is twofold:

• stimulates mobilization Ca 2+ ions from bone tissue, as it promotes the differentiation of monocytes and macrophages into osteoclasts, destruction of the bone matrix, reduction in the synthesis of type I collagen by osteoblasts,
• increases mineralization bone matrix, as it increases the production of citric acid, which forms insoluble salts with calcium here.

4. In addition, as shown in the last decade, vitamin D, influencing the work of about 200 genes, is involved in proliferation And differentiation cells of all organs and tissues, including blood cells and immunocompetent cells. Vitamin D regulates immunogenesis and reactions immunity, stimulates the production of endogenous antimicrobial peptides in the epithelium and phagocytes, limits inflammatory processes by regulating the production of cytokines.

Generalized diagram of the effects of calcitriol

Hypovitaminosis D

Currently, vitamin D deficiency is associated with increased risk development

• osteoporosis,
• viral infections (!), usually in the Russian Federation this is the flu,
• arterial hypertension,
• atherosclerosis,
• autoimmune diseases,
• diabetes mellitus,
• multiple sclerosis,
• schizophrenia,
• tumors of the mammary and prostate glands,
• duodenal and colon cancer.

Acquired hypovitaminosis

It often occurs with nutritional deficiency (vegetarianism), with insufficient insolation in people who do not go outside, with national characteristics of clothing.
Hypovitaminosis can also be caused by a decrease in hydroxylation calciferol (diseases liver And kidney) and violation suction and lipid digestion (celiac disease, cholestasis).

Vitamin D deficiency affects 50% of the world's population.
In northern European countries, the prevalence of deficiency reaches 85%.
It has been shown that in winter in the Russian Federation, vitamin D deficiency is found in more than 90% of the population.

Clinical picture

The most famous, “classic” manifestation of vitamin D deficiency is rickets, which develops in children from 2 to 24 months. With rickets, despite being supplied with food, calcium is not absorbed in the intestines and is lost in the kidneys. This leads to a decrease in the concentration of calcium in the blood plasma, impaired mineralization of bone tissue and, as a consequence, osteomalacia (softening of the bone). Osteomalacia is manifested by deformation of the bones of the skull (tuberosity of the head), chest (chicken breast), curvature of the lower leg, rachitic rosary on the ribs, enlargement of the abdomen due to hypotonia of the muscles, delayed teething and overgrowth of the fontanelles.

U adults also observed osteomalacia, i.e. Osteoid continues to be synthesized, but is not mineralized. In addition to bone tissue disorders, there is general hypotension of the muscular system, damage to the bone marrow, gastrointestinal tract, lymphoid system, and atopic conditions.

The influenza virus is detected in the human body all year round, but epidemics of the disease in northern latitudes occur only in winter, when the level of vitamin D in the blood reaches its minimum values. Therefore, a low seasonal supply of vitamin D, rather than an increase in viral activity, is considered by some researchers to be the cause of influenza epidemics during the cold months of the year.

Hereditary hypovitaminosis

IN itamin D-dependent hereditary rickets type I, in which there is a recessive renal defect α1-hydroxylase. Manifested by developmental delay, rachitic skeletal features, etc. Treatment is calcitriol preparations or large doses of vitamin D.

Vitamin D-dependent hereditary rickets type II, in which a defect is observed tissue receptors calcitriol. Clinically, the disease is similar to type I, but additionally alopecia, milia, epidermal cysts, and muscle weakness are noted. Treatment varies depending on the severity of the disease, but large doses of calciferol help.

Vitamin D-resistant rickets. It is observed in de Toni-Debreu-Fanconi disease, an autosomal recessive disease in which the proximal renal tubules are affected. Vitamin D deficiency manifests itself as rickets-like skeletal deformities, bone pain, fractures, and diffuse osteomalacia.

Hypervitaminosis

Cause

Excessive consumption with drugs (at least 1.5 million IU per day).

Clinical picture

Early signs of vitamin D overdose include nausea, headache, loss of appetite and body weight, polyuria, thirst and polydipsia. There may be constipation, hypertension, and muscle stiffness.

Chronic excess of vitamin D leads to hypervitaminosis, which is characterized by:

• demineralization bones, leading to their fragility and fractures.
• increase ion concentrations calcium And phosphorus in the blood, leading to calcification of blood vessels, lung and kidney tissue.

Dosage forms

Vitamin D– fish oil, ergocalciferol, cholecalciferol, aquadetrim, detrimax, calcium D3-nycomed.

Ergocalciferol (vitamin D2), which forms the basis of some drugs, is not able to maintain the level of the active form of vitamin D in the blood for a long time, and is not suitable for patients with moderate to severe deficiency.

Active forms of vitamin D(1α-hydroxycalciferol, calcitriol) – alfacalcidol, osteotriol, oxydevit, rocaltrol, forcal.

The main benefit of vitamin D for the human body is its ability to absorb calcium. The latter, in turn, is necessary for the growth of skeletal bones. What else is vitamin D useful for? Not everyone knows, but it nevertheless performs a number of vital functions in the body.

The role of vitamin D in the human body is not limited to the absorption of calcium. In addition, it strengthens the human defense system through the synthesis of immune cells. This allows the body to fight a wide variety of infections.

Absorbed calcium not only strengthens bone tissue, but also nerve fibers. Which in turn has a positive effect on the functioning of the entire human nervous system. Thus, it provides benefits in the fight against, for example, multiple sclerosis. The functioning of the human endocrine system cannot be complete without it. It regulates the functioning of the pancreas, which promotes the production of glucose.

And another important function is rejuvenation of the body. This process occurs due to the constant replacement of old cells with new ones. And vitamin D is involved in this process of cell replacement; this feature allows us to overcome cancer.

"Sunshine Vitamin"

Vitamin D and the sun are very strongly connected, it is not for nothing that its second name is “sunny”. When analyzing vitamin D, what it is useful for and how it helps a person, one cannot help but touch upon the topic of how it is synthesized in the body.

In fact, it is not produced under the sun's rays, but specifically under the influence of ultraviolet radiation, which, in fact, is part of solar radiation. Ultraviolet light, entering the epidermis layer, converts the substance located there into vitamin D.

It is produced in the amount in which the body received ultraviolet radiation. That is, if a person’s skin is dark in color, then there will be little vitamin D in such skin, and if the skin is white and its sun reflectance coefficient is low, then a large amount of vitamin D is synthesized.

But it is not only produced in the sun. It is found in large quantities in fatty sea fish. This fact does not allow pale-skinned residents of northern countries with weak solar activity to experience a lack of vitamin D.

The older a person is, the less vitamin D is produced in his body. This leads to various diseases, from osteoporosis to cancer. This is due not only to weak skin activity, but also to a person’s lifestyle, because older people rarely go outside.

Another interesting feature is its ability to accumulate in the body. There are situations when it is impossible to get it, and that’s when the “emergency” reserve created in the body in fatty tissues comes in handy. This ability is explained by the fact that it is very well soluble in lipids. This feature allows a person to survive a long dark winter and see the spring sun again.

What influences the content

The level of vitamin D in the body depends not only on the sun or its absence. There are a number of other reasons leading to a decrease in its level:

1. Production is highly dependent on human diet. And if he is a convinced vegetarian, then he voluntarily deprives himself of this important component, since this substance is contained only in animal or fish oil.
2. Sometimes a person is forced to undergo anthracite therapy, and it greatly reduces its content in the body.
3. Man has no control over time, which is why old people suffer from vitamin deficiency. D.
4. A pregnant or lactating woman should take the drug, because during this period of life, it is produced in her body in extremely small doses.

Symptoms of vitamin deficiency

When there is no vitamin D in the body and the sun does not appear for several months and a person’s diet does not contain foods containing the necessary substances, the following symptoms of vitamin deficiency begin to appear:

1. Bones become porous and brittle.
2. The man loses sleep.
3. Lost appetite.
4. The deficiency affects the quality of vision; it deteriorates significantly.
5. Dryness and burning occurs in the respiratory tract.
6. The general well-being of a person worsens, weakness occurs in the arms and legs.
7. Performance decreases due to rapid fatigue.

If one or several symptoms appear, you should immediately seek professional help. Since the therapy in this case is complex, and such a problem cannot be solved in one day, the sooner treatment begins, the higher the chance of completely restoring the level.

Vitamin D deficiency in men and women

A lack of vitamin D for men and women has an individual effect, so it makes sense to consider this problem in the context of specifically male and female problems. Vitamin D is extremely important for men. And this need lies in the metabolic characteristics of the male body. Namely, if there is not enough of it, bone tissue that is not supported by calcium is destroyed. When this happens, testosterone begins to strengthen the bone tissue, while a deficiency of this hormone occurs in other organs. Thus, without testosterone, a man loses sexual strength, becomes physically weaker, and loses muscle mass.

But this is not the worst thing. We must not forget that testosterone is not calcium; it cannot 100% fulfill its functions of strengthening bones. Therefore, osteomalacia and osteoporosis are added to sexual dysfunction and weight loss.

Absence also has a negative effect on a woman’s body. In addition to the problems common to men, women may experience problems with pregnancy due to a lack of calcium. Indeed, in this position, women need 4 times more calcium than, for example, a young unmarried girl. Its influence for nursing mothers cannot be overestimated; her milk must be saturated with calcium, otherwise the child will not grow up strong and healthy.

Increased vitamin D is prescribed not only for mothers and pregnant women. It is also useful for women employed in production, living in conditions with harsh climates and unfavorable environmental conditions.

Restoring normal levels

If a person is diagnosed with vitamin deficiency, with a pronounced lack of vitamin D, special therapy is prescribed. It includes a special diet, medications and a certain lifestyle.

1. Diet. A nutritionist knows what vitamin is in this or that product. It is he who can prescribe the correct diet that restores the level of D in the blood. The largest amount of it is found in the meat and fat of marine fish. You can eat fish, drink its fat, and then you won’t have problems with calcium for the rest of your life. This is explained by the fact that slave fat contains omega-3 and omega-6 acids.
2. Medicines. Medications are used to increase calcium and vitamin D levels.
3. Sun. Anyone understands what time of day you need to go for a walk to “refuel” with vitamin D - during the day when the sun is shining.

But in order for it to be completely absorbed by the body, it should be consumed together with foods containing proteins, phosphorus, calcium and vitamins A and C. By the way, they are found in the same sea fish. The human body needs them, no matter where it lives. And if the place is far from the sea, fish oil must be taken in capsule form. You need to eat at least one such capsule per day. It is necessary to give fish oil to children immediately after weaning them from breastfeeding. Replenishing vitamin D with the help of fish can be pleasant, because heat treatment does not destroy it, so you can prepare various dishes from fish.

Milk is needed to strengthen bones, it is known. But to enrich milk with vitamin D, you can irradiate it with ultraviolet light. It was American scientists who determined that ultraviolet radiation gives such an effect. And not only in relation to milk, almost any product can be irradiated with ultraviolet light.

The human body needs animal proteins and fats, it is necessary to give them to it. Pork is suitable for this. Chicken or duck meat, chicken eggs, beef liver. The amount of vitamin contained in these products cannot be found anywhere else. And if a person is a convinced vegetarian, then he must eat huge quantities of different cereals and salads a day in order to somehow maintain its level in the body.

The most famous and effective remedy is Calcium D3 Nycomed. In order to restore the daily norm, you need to take only one tablet. The drug can be taken by both children and adults. The dosage is prescribed individually, depending on the person’s condition and age.

Another well-known drug is Aquadetrim. This drug is prescribed to the youngest patients, from 1 month. It prevents the development of rickets in children and strengthens their bones. The same drug is prescribed to a pregnant woman.

“Calcium citrate” is prescribed for bone damage, such as a fracture or osteoporosis.

There are other drugs to restore levels. But any of them must be prescribed by a doctor, since not all people are affected by its positive effect. Some of them may have serious side effects or complications. For example, those who have chronic liver or kidney diseases.

Harm from vitamin D

So, vitamin D - its benefits and harms. If no questions arise regarding the benefits, then one cannot help but mention its harm. Harm may well occur if the person taking the drug is seriously ill with kidney or liver failure. Its effect on the body can be negative if a person has pulmonary tuberculosis or duodenal and gastric ulcers.

Good day, dear visitors of the project “Good IS!” ", section " "!

I am pleased to present to your attention information about vitamin D.

The main functions of vitamin D in the human body are: ensuring the absorption of calcium from food in the small intestine (mainly in the duodenum), stimulating the synthesis of a number of hormones, and also participating in the regulation of cell reproduction and metabolic processes.

General information

Vitamin D, aka calciferol(lat. Vitamin D, Calciferol) - a group of biologically active substances that regulate metabolism with.

Also called vitamin D "sunshine vitamin".

Forms of Vitamin D:

Vitamin D1- combination of ergocalciferol with lumisterol, 1:1.

Vitamin D2 (ergocalciferol) ( Ergocalciferol) - isolated from yeast. Its provitamin is ergosterol;
(3β,5Z,7E,22E)-9,10-secoergosta-5,7,10 (19),22-tetraen-3-ol.
Chemical formula: C28H44O.
CAS: 50-14-6.
Vitamin D2 is very toxic, a dose of 25 mg is already dangerous (20 ml in oil). It is poorly excreted from the body, which leads to a cumulative effect.
Main symptoms of poisoning: nausea, malnutrition, lethargy, increased body temperature, muscle hypotension, drowsiness, followed by severe anxiety, convulsions.
Since 2012, Ergocalciferol has been excluded from the list of vital and essential drugs.

Vitamin D3 (cholecalciferol, Cholecalciferol)- isolated from animal tissues. Its provitamin is 7-dehydrocholesterol;
Systematic name:(3beta,5Z,7E)-9,10-Secocholesta-5,7,10(19)-trien-3-ol.
Chemical formula: C27H44O.
CAS: 67-97-0.
Restrictions on use: Organic heart damage, acute and chronic liver and kidney diseases, gastrointestinal diseases, gastric and duodenal ulcers, pregnancy, old age.
Contraindications: Hypersensitivity, hypercalcemia, hypercalciuria, calcium nephrourolithiasis, prolonged immobilization (large doses), active forms of pulmonary tuberculosis.

Vitamin D4 (22, 23-dihydro-ergocalciferol).
Systematic name:(3β,5E,7E,10α,22E)-9,10-secoergosta-5,7,22-trien-3-ol.
Chemical formula: C28H46O.
CAS: 67-96-9.

Vitamin D5 (24-ethylcholecalciferol, sitocalciferol). Isolated from wheat oils.

Vitamin D6 (22-dihydroethylcalciferol, stigma-calciferol).

Vitamin D usually means two vitamins - D2 and D3 - ergocalciferol and cholecalciferol, but more of them are D3 (cholecalciferol), so often on the Internet and other sources, vitamin D is labeled as cholecalciferol.

Vitamin D (cholecalciferol and ergocalciferol) are colorless and odorless crystals that are resistant to high temperatures. These vitamins are fat soluble, i.e. soluble in fats and organic compounds and insoluble in water.

Vitamin D units

The amount of vitamin D, like , is usually measured in international units (IU).

The activity of vitamin D preparations is expressed in international units (IU): 1 IU contains 0.000025 mg (0.025 mg) of chemically pure vitamin D. 1 μg = 40 IU

1 IU = 0.025 mcg cholecalciferol;
40 IU = 1 mcg cholecalciferol.

Vitamin D in history

The first mention of a disease caused by vitamin D deficiency, rickets, was found in the works of Soranus of Ephesus (98–138 AD) and the ancient physician Galen (131–211 AD).

Rickets was first briefly described only in 1645 by Whistler (England), and in detail by the English orthopedist Gleason in 1650.

In 1918, Edward Melanby proved in an experiment on dogs that cod oil acts as an antirachitic agent due to the content of a special vitamin. For some time it was believed that the antirachitic activity of cod oil depended on , already known at that time.

Later in 1921, McCollum, by passing a stream of oxygen through cod oil and inactivating vitamin A, discovered that the antirachitic effect of the oil persisted after that. Upon further search, another vitamin was found in the unsaponifiable part of cod oil, which has a strong anti-rachitic effect - vitamin D. Thus, it was finally established that food substances have the property of preventing and curing rickets mainly depending on the greater or lesser content of the vitamin in them D.

In 1919, Guldchinsky discovered the effective action of a mercury-quartz lamp (artificial “mountain sun”) in the treatment of children with rickets. From this period, insufficient exposure of children to ultraviolet sunlight began to be considered the main etiological factor of rickets.

And only in 1924 A. Hess and M. Weinstock obtained the first vitamin D1-ergosterol from vegetable oils after exposure to ultraviolet rays with a wavelength of 280–310 nm.

In 1928, Adolf Windaus received the Nobel Prize in Chemistry for the discovery of 7-dehydrocholesterol, a precursor to vitamin D.

Later, in 1937, A. Windaus isolated 7-dehydrocholesterol from the surface layers of pig skin, which was converted into active vitamin D3 under ultraviolet radiation.

The main function of vitamin D is to ensure normal growth and development of bones, prevent rickets and. It regulates mineral metabolism and promotes calcium deposition in bone tissue and dentin, thus preventing osteomalacia (softening) of bones.

Upon entering the body, vitamin D is absorbed in the proximal small intestine, and always in the presence of bile. Part of it is absorbed in the middle sections of the small intestine, a small part - in the ileum. After absorption, calciferol is found in the composition of chylomicrons in free form and only partially in the form of ester. Bioavailability is 60-90%.

Vitamin D affects general metabolism in the metabolism of Ca2+ and phosphate (HPO2-4). First of all, it stimulates the absorption of calcium, phosphates and calcium from the intestine. An important effect of the vitamin in this process is to increase the permeability of the intestinal epithelium to Ca2+ and P.

Vitamin D is unique - it is the only vitamin that acts as both a vitamin and a hormone. As a vitamin, it maintains the levels of inorganic P and Ca in the blood plasma above the threshold value and increases the absorption of Ca in the small intestine.

The active metabolite of vitamin D, 1,25-dioxycholecaciferol, which is formed in the kidneys, acts as a hormone. It affects the cells of the intestines, kidneys and muscles: in the intestines it stimulates the production of a carrier protein necessary for the transport of calcium, and in the kidneys and muscles it enhances the reabsorption of Ca++.

Vitamin D3 affects the nuclei of target cells and stimulates the transcription of DNA and RNA, which is accompanied by increased synthesis of specific proteins.

However, the role of vitamin D is not limited to protecting bones; it affects the body's susceptibility to skin diseases, heart disease and cancer. In geographic areas where food is poor in vitamin D, the incidence of vitamin D is increased, especially in youth.

It prevents muscle weakness, improves immunity (the level of vitamin D in the blood is one of the criteria for assessing the life expectancy of AIDS patients), and is necessary for the functioning of the thyroid gland and normal blood clotting.

Thus, with external use of vitamin D3, the characteristic scaly skin is reduced.

There is evidence that, by improving the absorption of calcium and magnesium, vitamin D helps the body restore the protective membranes surrounding the nerves, so it is included in the complex therapy of multiple sclerosis.

Vitamin D3 is involved in the regulation of blood pressure (particularly during pregnancy) and heartbeat.

Vitamin D inhibits the growth of cancer cells, making it effective in the prevention and treatment of breast, ovarian, prostate, brain cancer, and leukemia.

Daily requirement of vitamin D

What factors reduce the level of vitamin D in our body?

The need for vitamin D is higher in people lacking ultraviolet radiation:

- living in high latitudes,
- residents of regions with high air pollution,
- working night shifts or simply leading a nocturnal lifestyle,
- bedridden patients who do not spend time outdoors.

In people with dark skin (Negroid race, tanned people), the synthesis of vitamin D in the skin is reduced. The same can be said for older people (their ability to convert provitamins into vitamin D is halved) and those who follow a vegetarian diet or eat insufficient amounts of fat.

Intestinal and liver disorders and gall bladder dysfunction negatively affect the absorption of vitamin D.

In pregnant and lactating women, the need for vitamin D increases, because Additional amounts are needed to prevent rickets in children.

Vitamin D2 (ergocalciferol) is prescribed to pregnant women to prevent rickets in children at 30-32 weeks of pregnancy in divided doses over 10 days, for a total course of 400,000-600,000 IU. Nursing mothers - 500 IU daily from the first days of feeding until the child starts using the drug.

In order to prevent rickets, children begin to be given ergocalciferol from three weeks of age, the total dose per course is 300,000 IU.

For the treatment of rickets, 2000-5000 IU is prescribed daily for 30-45 days.

When treating with large doses of vitamin D preparations, it is recommended to simultaneously prescribe, and.

For prevention purposes, vitamin D3 (cholecalciferol) is usually prescribed, usually at a dose of 300-500 IU per day.

Beware, vitamin D!

Vitamin D is fat-soluble and therefore stored in the body, so if you overdose on it, serious problems can occur.

Because vitamin D increases calcium levels in the blood, excess vitamin D intake can lead to excess calcium levels. In this case, calcium can penetrate the walls of blood vessels and provoke the formation of atherosclerotic plaques. This process can be accelerated by a deficiency of magnesium in the body.

Vitamin D preparations are contraindicated for diseases such as:

Video about vitamin D

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Vitamin D or ergocalciferol belongs to the group of fat-soluble vitamins, formed under the influence of ultraviolet rays in the tissues of plants and animals from sterols. The vitamin is soluble in organic compounds and fats, but does not have the ability to dissolve in water.

Vitamins of group D include:

• Vitamin D2 – ergocalciferol, obtained from yeast; its provitamin is ergosterol;
• Vitamin D3 – cholecalciferol isolated from animal tissues; 7-dehydrocholesterol is considered its provitamin;
• Vitamin D4 – 22, 23-dihydro-ergocalciferol;
• Vitamin D5 isolated from wheat oils; sitocalciferol (24-ethylcholecalciferol);
• Vitamin D6 – stigma-calciferol (22-dihydroethylcalciferol).

Today, two compounds are considered vitamin D - cholecalciferol and ergocalciferol (D2 and D3). The activity of vitamin-based drugs is expressed in IU - international units.

1 IU contains 0.025 mcg of vitamin D in chemically pure form.

Sources of Vitamin D

The production of vitamin D in the body is carried out from provitamins that enter the body in finished form from foods or are formed from cholesterol under the influence of ultraviolet rays.

If a person’s skin receives enough ultraviolet radiation, his need for vitamin D is more than compensated. However, vitamin D is also found in foods: egg yolk, fish oil, fermented milk products; however, consumption of food sources alone cannot guarantee full coverage of our body’s vitamin D needs.

Vitamin D in foods:

• Herring (400-1500 IU/100 g);
• Pork liver (40-50 IU/100 g);
• Beef liver (40-50 IU/100 g);
• Butter (10-150 IU/100 g);
• Egg yolk (50-400 IU/100 g).

Effect of vitamin D

The main function performed by the vitamin is to ensure complete absorption of phosphorus, calcium and magnesium, necessary for the normal development of the skeletal system. This substance promotes sufficient calcium deposition in dentin and bones, preventing the occurrence of osteoporosis and rickets, preventing softening (osteomalacia) of bones.

The role of vitamin D is not limited to protecting bones: it improves immunity, prevents muscle weakness, ensures normal blood clotting and the functioning of the thyroid gland. By improving mineral metabolism, vitamin D takes part in the restoration of the protective membranes surrounding the nerves, thus becoming part of the complex therapy and prevention of multiple sclerosis.

In addition, vitamin D effectively regulates heart rate and blood pressure, including in pregnant women, and prevents the growth of cancer cells. When vitamin D3 is applied externally, the severe scaly skin characteristic of psoriasis can be reduced.

Vitamin D requirement

The main source of vitamin D is the sun. To fully satisfy the body's need for vitamin D, it is enough to be exposed to solar ultraviolet radiation for 15-20 minutes a day, especially in the morning and sunset hours. However, the winter period, smoky atmosphere and pronounced tanning can reduce the production of the vitamin in the body. The same can be said about older people, whose body loses the ability to synthesize vitamin D from provitamins by half and about those who prefer to adhere to various diets and eat small amounts of fat.

Vitamin D requirements are:

• For full-term newborns – 500-700 IU/day;
• In newborns weighing less than 2500 g – 1000-1400 IU/day;
• In children from 5-12 years old – 400-500 IU/day;
• In adolescents – 500-600 IU/day;
• In adults from 20-50 years old – 300-400 IU/day;
• For pregnant and lactating women – 600-800 IU/day;
• In older people – 600-800 IU/day.

Symptoms of hypovitaminosis

Lack of vitamin D causes osteomalacia and the appearance of rickets, a disease of the skeletal system characterized by impaired bone formation. In milder forms, symptoms of vitamin D deficiency include:

• Burning sensation in the throat and mouth;
• Weight loss, loss of appetite;
• Deterioration of vision;
• Insomnia.
• Lack of vitamin D (vitaminosis);
• Osteoporosis;
• Osteomyelitis;
• Osteomalacia;
• Bone fractures;
• Hypophosphatemia, hypocalcemia;
• Osteodystrophy of renal origin;
• Hypoparathyroidism, including complicated by osteomalacia;
• Lupus erythematosus;
• Chronic gastritis;
• Chronic enteritis;
• Chronic pancreatitis;
• Enterocolitis complicated by osteoporosis;
• Tuberculosis.

Indications for taking vitamin D

Additional intake of vitamin D is advisable for caries and disorders in the development of teeth, psoriasis, spasmophilia, hay fever, hemorrhagic diathesis, postmenopause, as well as in order to increase the immune properties of the body. Taking vitamin D is advisable during pregnancy occurring in the autumn-winter period and treatment with glucocorticoid drugs.

In addition, preventive use of the vitamin may be required for people living and working in the Arctic Circle, metro employees, and miners.

Symptoms of hypervitaminosis

Taking inadequate doses of vitamin D can lead to the following conditions:

• Severe headaches, muscle pain, joint pain;
• Increased blood pressure;
• Loss of appetite, nausea, vomiting, weakness, stool disorders;
• Fever, difficulty breathing, increased heart rate.

Chronic vitamin D poisoning can cause symptoms such as:

• The appearance of osteoporosis, bone demineralization, stroma resorption;
• Calcification of blood vessels and heart valves;
• Deposition of calcium salts in the intestines, lungs, kidneys, leading to disruptions in the functioning of these organs.

Interaction

It is recommended to stop taking vitamin D simultaneously with hyperlipidemic drugs, since drugs that lower blood cholesterol levels can interfere with its absorption.

Mineral laxatives, steroid hormones, antacids, diphenin and barbiturates also interfere with the absorption of vitamin D.

Taking vitamin D reduces the activity of cardiac glycosides, and significant doses of the vitamin can lead to iron deficiency in the body.

Full metabolism of vitamin D in the liver is impossible with a lack of vitamin E.