What vitamin is found in sunlight. Vitamin D - solar hormone

Vitamin D - Calciferol, Ergosterol, Viosterol

We acquire it through sunlight or through food. The ultraviolet rays act on the oils of the skin, promoting the formation of this vitamin, which is then absorbed into the body. Vitamin D is formed in the skin under the action of sunlight from provitamins. Provitamins, in turn, partially enter the body in ready-made from plants (ergosterol, stigmasterol and sitosterol), and partially formed in the tissues of their cholesterol (7-dehydrocholesterol (vitamin D provitamin 3).

When taken orally, vitamin D is absorbed from fat through the walls of the stomach.

It is measured in International Units (IU). The daily dose for adults is 400 IU or 5-10 micrograms. After getting a tan, the production of vitamin D through the skin stops.

Benefit: Properly utilizes calcium and phosphorus, necessary for strengthening bones and teeth. When taken together with vitamins A and C, it helps in the prevention of colds. Helps in the treatment of conjunctivitis.

Diseases caused by vitamin D deficiency: rickets, severe tooth decay, osteomalacia*, senile osteoporosis.

Vitamin D belongs to the group of fat-soluble vitamins with anti-rachitic effects (D 1 , D 2 , D 3 , D 4 , D 5)

The D vitamins include:

vitamin D 2 - ergocalciferol; isolated from yeast, its provitamin is ergosterol; vitamin D 3 - cholecalciferol; isolated from animal tissues, its provitamin - 7-dehydrocholesterol; vitamin D 4 - 22, 23-dihydro-ergocalciferol; vitamin D 5 - 24-ethylcholecalciferol (sitocalciferol); isolated from wheat oils; vitamin D 6 - 22-dihydroethylcalciferol (stigma-calciferol).

Today, vitamin D is called two vitamins - D 2 and D 3 - ergocalciferol and cholecalciferol - these are colorless and odorless crystals, resistant to high temperatures. These vitamins are fat soluble, i.e. fat soluble and organic compounds and insoluble in water.

They regulate the exchange of calcium and phosphorus: they participate in the process of calcium absorption in the intestine, interact with parathyroid hormone, and are responsible for bone calcification. In childhood, with vitamin D deficiency, due to a decrease in the content of calcium and phosphorus salts in the bones, the process of bone formation (growth and ossification) is disturbed, rickets develops . In adults, bone decalcification (osteomalacia) occurs.

The German chemist A. Windaus, who studied sterols for more than 30 years, in 1928 discovered ergosterol - provitamin D, which turns into ergocalciferol under the influence of ultraviolet rays. It was found that under the influence of ultraviolet rays a certain amount of vitamin D can be formed in the skin, and irradiation can be either solar, and with the help of a quartz lamp. . It has been calculated that a 10-minute irradiation of animals has the same effect on the body as the introduction of 21% fish oil into the diet. In irradiated foods, vitamin D is formed from special fat-like substances (sterols). IN Lately in animal husbandry, ultraviolet irradiation of animals, especially young animals, as well as feed is widely used.

Main sources:fish fat, caviar, liver and meat, egg yolk, animal fats and oils, sardines, herring, salmon, tuna, milk. hay flour, Vitamin D is also found in large quantities in egg yolk, yeast, good hay, vegetable oil, grass meal and other products. As a rule, plants do not contain the vitamin, but they contain its provitamin ergosterol, which is converted into vitamin D in the body of animals.

daily requirement 2.5 mcg, for children and pregnant women - 10 mcg. Disorders of the intestines and liver, gallbladder dysfunction negatively affect the absorption of vitamin D.

In pregnant and lactating animals, the need for vitamin D increases, because. an additional amount is needed to prevent rickets in children.

Action

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

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

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

Vitamin D is unique - it is the only vitamin that acts both as a vitamin and as a hormone. As a vitamin, it maintains the level 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 has an effect on 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 increases the reabsorption of Ca ++.

Vitamin D 3 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 atherosclerosis, arthritis, diabetes, especially juvenile diabetes, is increased.

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 thyroid gland and normal blood clotting.

So, with the external use of vitamin D 3, the scaly skin characteristic of psoriasis decreases.

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 D 3 is involved in the regulation of blood pressure (in particular, with hypertension in pregnant women) and heartbeat.

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

Hypovitaminosis. Vitamin D deficiency in children leads to rickets. The main manifestations of this disease are reduced to the symptoms of calcium deficiency. First of all, osteogenesis suffers: there is a deformation of the skeleton of the limbs (their curvature as a result of softening - osteomalacia), the skull (late fusion of fontanelles), chest(the appearance of a kind of "rosary" on the bone-cartilaginous border of the ribs), teething is delayed. Muscle hypotension develops (enlarged belly), neuromuscular excitability increases (the baby has a symptom of nape baldness due to frequent rotation of the head), seizures may occur. In an adult, calcium deficiency in the body leads to caries and osteomalacia; in the elderly - to the development of osteoporosis (decrease in density bone tissue due to a violation of osteosynthesis), the destruction of the inorganic matrix is ​​explained by the increased "washout" of calcium from the bone tissue and the violation of calcium reabsorption in the renal tubules in vitamin D deficiency.

The diagram below shows inhibition (dashed arrow) of absorption, decreased calcium entry into the bone, and decreased calcium excretion in vitamin D deficiency. Simultaneously, in response to hypocalcemia, parathyrin is secreted and increased (solid arrow) calcium from the bone into the bloodstream (secondary hyperparathyroidism).

Symptoms of hypovitaminosis

The main symptom of vitamin D deficiency is rickets and softening of the bones (osteomalacia).

Milder forms of vitamin D deficiency present with symptoms such as:

loss of appetite, weight loss,

burning sensation in the mouth and throat,

insomnia,

deterioration of vision.

Rickets - one of the most common childhood diseases - has been known since time immemorial. Paintings by Flemish artists of children with twisted spines, arms and legs clearly point to the spread of rickets in the 15th century. Rickets became widespread in Great Britain - it was also called the "English disease". As it became known later, ultraviolet light is needed to activate the anti-rachitic vitamin, so the foci of rickets have become big cities with dense buildings and smoke. With rickets, the most pronounced disorders are in the bones of the legs, chest, spine and skull. Cartilage and bone tissues become abnormally soft, which leads to their deformation and curvature. Rickets is also possible with a sufficient content of the vitamin in food, but with a violation of its absorption in the digestive tract (digestive disorders at an early age).

With a lack of vitamin D in animals, the content of calcium and phosphorus in the blood decreases, appetite disappears, the work of the respiratory organs is disturbed, growth is retarded, softening of the limbs, brittle bones appear. Sometimes there are cramps in the muscles of the head, neck and limbs. The most pronounced rickets occurs in young animals. It has long been known that rickets is well treated with fish oil.

Hypervitaminosis D. Hypervitaminosis D is quite dangerous (occurs at doses that are many times higher than therapeutic), because this causes hypercalcemia of the body and calcification of internal organs: kidneys, stomach, lungs, large blood vessels. Excess vitamin D is deposited in the liver and can cause poisoning.

Excessive intake of vitamin D leads to intoxication and is accompanied by severe demineralization of bones - up to their fractures. The calcium content in the blood rises. This leads to calcification of soft tissues, especially the kidneys are prone to this process (stones are formed and kidney failure develops). An increase in the level of calcium (and phosphorus) in the blood is explained by the following: 1) bone resorption (solid arrow); 2) an increase in the intensity of calcium and phosphorus absorption in the intestine; 3) an increase in their reabsorption in the kidneys (ie, inhibition of urinary excretion - dotted line).

IN normal conditions an increase in the calcium content in the blood will lead to the formation of inactive 24,25 (0 H) 2-D3, which does not eliminate bone resorption (“resorption”), however, with hypervitaminosis D, this mechanism becomes ineffective / Interestingly, skin pigmentation (tanning) is a protective factor that protects against excessive formation of vitamin D during UV irradiation of the skin. However, light-skinned people in northern countries who lack solar insolation do not usually develop vitamin D deficiency conditions, as their diet includes fish oil.

Metabolism. Vitamins of group D are absorbed like vitamin A. In the liver, vitamins are hydroxylated by the microsomal oxygenase system at C-25 (25 (OH) -D3, i.e. 25-hydroxycholecalciferol is formed from vitamin D), and then transferred by the blood stream using a specific transport protein into the kidneys. In the kidneys, the second hydroxylation reaction at C-1 is carried out with the help of mitochondrial oxygenases (1,25 (OH) 2-D3 is formed, i.e. 1,25-dihydroxycholecalciferol, or calcitriol). This response is activated by parathyroid hormone secreted by the parathyroid gland when blood calcium levels decrease. If the level of calcium is adequate to the physiological needs of the body, secondary hydroxylation occurs at C-24 (instead of C-1), while an inactive metabolite 1,24 (OH) 2-D3 is formed. Vitamin C takes part in the hydroxylation reactions.

Vitamin D3 is stored in adipose tissue. It is excreted mainly with feces in unchanged or oxidized form, as well as in the form of conjugates.

Vitamin H - Biotin, coenzyme R

Vitamin H water soluble, relatively new member of the family b vitamins.

Biotin is needed for the synthesis of ascorbic acid. Essential for normal fat and protein metabolism.

RNP for adults 150 - 300 mcg. Can be synthesized by intestinal bacteria. Raw eggs prevent its absorption by the body. Synergistic with vitamins B2, B6, niacin, A and keeps the skin healthy.

Benefit: Helps prevent gray hair. Eases muscle pain. Reduces the appearance of eczema and dermatitis.

Diseases caused by biotin deficiency: disorders of fat metabolism.

Best Natural Sources: nuts, fruits, brewer's yeast, beef liver, milk, kidney and brown rice, egg yolk.

In 1935-1936. Kogi and Tonnies first isolated crystalline biotin from the yolk of eggs. For this purpose, they used 250 kg of egg yolks and obtained 100 mg of biotin with a melting point of 148°.

Known amino acid derivatives of biotin, among which the most

studied biocytin, which has a high activity for many microorganisms.

It is a peptide of biotin and lysine. At present, the cause of pathological changes that occur when animals are fed raw egg white. It contains avidin, a protein that specifically binds to biotin (introduced orally with food products or synthesized by intestinal microorganisms) into an inactive complex and thus prevents its absorption.

A record amount (6.81 mcg/g) was found in shark liver.

The most vitamin-rich liver, kidneys, adrenal glands; the heart and stomach contain the average, and the brain tissue, lungs and skeletal muscles the minimum amount of biotin.

The richest in vitamins are pork and beef liver, kidneys, bull's heart, egg yolk, and from plant products - beans, rice bran, wheat flour and cauliflower. In animal tissues and yeast, biotin is found predominantly in protein-bound form, while in vegetables and fruits it is found in the free state.

Biosynthesis of biotin.

The biosynthesis of biotin is carried out by all green plants, some bacteria

and mushrooms. The study of biotin biosynthesis pathways began after the elucidation of the structure of its molecule. The chemical degradation of biotin proceeds through the formation of dethiobiotin, diaminopelargonic acid, and finally pimelic acid.

Interaction with other vitamins.

The connection of biotin with other vitamins, in particular with folic acid, vitamin B12 - ascorbic acid, thiamine and pantothenic acid, has been established. A particularly close relationship exists between biotin and folic acid. Biotin has a beneficial effect on general state organism and preservation ascorbic acid in tissues of scurvy guinea pigs. In turn, ascorbic acid slows down, although it does not prevent the development of biotin avitaminosis in rats.

With biotin deficiency, the content of thiamine in the liver, spleen, decreases. kidneys and brains of animals. In rats kept on a diet devoid of biotin, the content of vitamin B12 was higher than in control animals treated with biotin. These two vitamins are closely related to each other in the exchange of propionic acid in microorganisms and animals. Exists close connection between the biosynthesis of biotin and pantothenic acid in microorganisms and green plants (VV Filippov, 1962). Biotin alleviates the symptoms of pantothenic deficiency and, conversely, pantothenic acid alleviates the manifestation of biotin deficiency.

Biotin avitaminosis in animals it is characterized by cessation of growth and a drop in body weight (up to 40%), redness and peeling of the skin, loss of hair or feathers, the formation of a red swollen rim around the eyes in the form of “glasses”, atactic gait, swelling of the legs and a typical posture of an animal with a bent (kanga -ru-like) back. The dermatitis that develops in animals with biotin deficiency can be characterized as desquamation-type seborrhea, similar to that seen in children.

In rats, vitamin deficiency of biotin develops after 4-5 weeks of feeding the experimental diet, and in chickens, the first signs of vitamin deficiency appear after 3 weeks.

Apart from external signs, biotin vitamin deficiency causes profound morphological changes in tissues and organs, as well as metabolic disorders. Known changes in the thymus, skin and muscles of rats. Abundant hyperkeratosis, acanthesis and edema are characteristic. Destroyed hair shafts are mixed with hyperkeratotic plates. An expansion of the hair follicles, the openings of which are clogged with hyperkeratotic material, has been established. In the last phase of the development of avitaminosis, atrophy of fat in hyperkeratotic plates is observed. The lack of biotin in the diet of rats leads to a decrease in its content in tissues. In the liver and muscles, the amount of the vitamin is reduced by 5 times, and in the brain tissue by 15%. Pyruvic acid accumulates in the blood of avitaminous rats, acidosis develops, and the sugar concentration decreases. At the same time, glucosuria is not observed, but the content of reducing sugars in the liver decreases with their normal content in the muscles; animals develop creatinuria.

A person fully satisfies his need for biotin due to its synthesis by the intestinal microflora, therefore, hypovitaminosis can only be obtained in an experiment.

Hypovitaminosis can develop mainly with intestinal dysbacteriosis, which occurs, for example, as a result of taking antibiotics.

Symptoms of hypovitaminosis

Possible consequences of biotin deficiency: seborrheic dermatitis, anemia, depression, hair loss, high blood sugar, inflammation or pallor of the skin and mucous membranes, insomnia, loss of appetite, muscle pain, nausea, inflammation of the tongue, dry skin, high blood cholesterol.

Interaction

* Raw egg white contains a substance called avidin, the anti-vitamin biotin. This substance binds biotin and prevents its absorption into the blood. When heated, denaturation (irreversible structural damage) of avidin occurs in egg white, and therefore cooked eggs do not interfere with the absorption of biotin.

* Alcohol impairs the ability to absorb biotin, and therefore chronic alcohol abuse can lead to biotin deficiency.

* Oil fats that have been cooked or exposed to air for a long time slow down the absorption of biotin.

* Antibiotics, sulfur medications and saccharin also interfere with biotin absorption.

If you need long-term antibiotic treatment - this applies to both children and adults - biotin synthesis can be drastically reduced due to the death of beneficial intestinal bacteria, making additional intake necessary.

Vitamin H is indicated for hair loss and psoriasis, in cosmetics it is used as part of hair care products and masks.

Metabolism Biotin, bound to proteins, is supplied with food, with the help of proteinases it passes into a free state and is absorbed in the small intestine. When it enters the bloodstream, it reconnects with proteins (albumin) and enters the tissues. Biotin is retained mainly in the liver and kidneys. It is excreted unchanged in urine and feces. The coenzyme form of vitamin H is N5-carboxybiotin.

Structure and properties.

The structure of biotin is based on a thiophene ring, to which urea is attached, and the side chain is represented by valeric acid:

Biotin is a crystalline substance, highly soluble in water and alcohol. This is a stable compound, the biological activity of which does not change after boiling solutions and with the access of oxygen.

Empirical formula: C 10 H 16 O 3 N 2 S.

Description

Vitamin D- a fat-soluble element. It is often referred to as an anti-rachitic factor because it is essential for proper bone development and growth. Since the compound dissolves in fats, it accumulates in cells various organs. In nai large quantities the element is deposited in the liver and subcutaneous adipose tissue. There is always a certain amount of vitamin D left in the body, which has previously managed to accumulate. These reserves are used up if not enough substance is supplied with food. Deficiency rarely develops unless a person is in the sun for at least an hour a day, but this dangerous state like an overdose. In both cases it is possible serious violations in the work of various organs and tissues.

Vitamin D provides proper development and growth of bones in accordance with the age of the person. This is necessary for the formation of the musculoskeletal system, as well as for the prevention of rickets in children and adults. Also, the element stimulates the healing of bone tissue in case of fractures, cracks and other injuries. Since vitamin D is involved in maintaining the metabolism of calcium and phosphorus, it provides the prevention of osteoporosis.

In the body, the element is in the systemic circulation and maintains normal levels of calcium and phosphorus. Vitamin D also improves calcium absorption in the intestines. This prevents its deficiency and leaching from the bones. With a lack of vitamin D, the concentration of calcium in the blood decreases. It begins to wash out of the bones, so osteoporosis and other disorders occur.

The functions of vitamin D also include reducing the risk of developing diseases of the skin, heart and malignant tumors. element restrains active growth cancer cells, so it is used in complex treatment and for the prevention of breast, ovarian, prostate, blood and brain cancers. while maintaining normal level vitamin D in the body reduces the risk of diabetes, atherosclerosis and arthritis.

Another element prevents muscle weakness, strengthens the immune system, maintains normal blood clotting and thyroid function. Experimental studies show that vitamin D stimulates recovery nerve cells and fibers, curbing the progression of multiple sclerosis. He takes part in the normalization of pressure and heart rate. With the external use of preparations with vitamin D, the scaly skin in patients with psoriasis decreases.

Opening

The discovery of vitamin D solved a previously acute problem childhood rickets. After the American Elmer McCollum discovered vitamin A in fish oil in 1914, the English veterinarian Edward Mellenby observed that dogs fed fish oil do not suffer from rickets. This observation led him to the conclusion that it was vitamin A, or some substance related to it, that prevented rickets.

To clarify this issue, McColum in 1922 set up an experiment with a portion of fish oil, where vitamin A was neutralized. The dogs to whom he gave this product were successfully cured of rickets. So it was proved that not vitamin A is responsible for the cure for rickets, but another hitherto unknown vitamin. Since it was the fourth vitamin discovered by science, it was named the fourth letter of the Latin alphabet - D.

In 1923, the American biochemist Harry Stenbock demonstrated that irradiating food with ultraviolet light increased its vitamin D content. After such irradiation, standard food allowed the rats that were experimented on to recover from rickets. Around the same time, A.F. Hess proved that a person can produce vitamin D under the action of sunlight.

Stenbock, meanwhile, patented a method for ultraviolet irradiation of milk and other fatty foods in order to increase the content of the "solar vitamin" in them. This practice remains fairly common in the US. In Russian retail, dairy products with the addition of vitamin D are practically not represented.

Vitamin Forms

The name "vitamin D" means not one substance, but six at once. All of them have the characteristics of sterols and are designated by the term "vitamer", which means "a kind of vitamin".

So, what is included in the collective name "vitamin D"? This:

• D1 - it is possible to create exclusively in laboratories, in nature in in kind this form of the vitamin is not found;
• D2 is ergocalciferol, a substance derived from yeast. In fact, it is a synthetic version of the vitamin. In this form, D2 plays a role food additive in bread and milk mixtures. Provitamin D2 - ergosterol;
• D3 - cholecalciferol. This natural form of the vitamin is easily found in animal products. The provitamin for D3 is 7-dehydrocholesterol;
• D4 - found in the skin, and under the influence of the sun is transformed into D3;
• D5 - sitocalciferon. Made from wheat grain oils;
• D6 - stigmacalciferol. Found in some plant species.

However, of all these forms of calciferol, the body experiences greatest need in fat-soluble forms D2 and D3. They have the highest biological activity, are found in food, withstand thermal influences, and can also be easily synthesized in skin cells under the influence of ultraviolet radiation. Therefore, most often, when talking about vitamin D and its role in the human body, these two vitamers are meant.

It is important to note that the functions and meaning of all vitamers are the same. Their main differences are the method of obtaining and biological activity.

How is a vitamin absorbed?

Part of the vitamin is synthesized independently in the skin, and partly obtained by the body from food. With the independent production of a substance, the compound can be absorbed into the body directly through the epidermis, since the formation of calciferol occurs when light is exposed to natural oils skin. When additionally taken in preparations, the compound is absorbed through the stomach. To make this process as efficient as possible, it is recommended to simultaneously provide a sufficient amount of retinol acetate, tocopherol, ascorbic acid, B vitamins, as well as calcium and phosphorus trace elements in the diet.

Top 5 Benefits of Vitamin D

Benefit 1: Strengthen Bones

When it comes to strong bones The first thing that comes to mind is calcium. Calcium is indeed the main nutrient for bone health and bone mineral density, but don't forget the importance of vitamin D.

Studies have shown that vitamin D is a strong stimulant of calcium release in the bones, which makes them stronger and healthier. If you don't get enough vitamin D, your body starts to slow or stop calcium from getting to your bones, and eventually the calcium goes back into your bloodstream instead of your bones. Over time, this cycle makes the bones weak and exposes them to more high risk fractures.

Benefit 2: Improved muscle performance

During short periods of intense training, vitamin D intake may contribute to strength gains. According to a study published in the Iranian Journal of Public Health in 2010, more than 70 percent of men aged 20-29 suffered from some degree of vitamin D deficiency.

Vitamin D deficiency is relatively common among athletes and is the cause muscle weakness and atrophy, mainly atrophy muscle fibers 2 types. Insufficient daily intake This vitamin is just as bad for muscle strength as skipping a day of leg exercise.

Benefit 3: Protection against cardiovascular disease

The classic function of vitamin D is to increase calcium absorption to maintain optimal bone health, but did you know that it has a protective effect on the heart? Data latest research showed that people with vitamin D deficiency are exposed to increased risk high blood pressure, heart disease, sudden cardiogenic death and heart failure.

Although the exact mechanisms of action have not yet been elucidated, vitamin D has been shown to help reduce arterial pressure, improves vascular elasticity (degree of elasticity of the arteries) and controls glycemic index. Support your heart health with vitamin D!

Benefit 4: Lower Risk of Type 2 Diabetes

Type 2 diabetes can lead to some devastating long-term complications, including nerve damage, heart disease, deterioration or loss of vision, and kidney failure. Recent evidence suggests that vitamin D plays a significant role in reducing the risk of type 2 diabetes, especially for those at increased risk for this deadly disease.

A number of observational studies have shown that higher intakes of vitamin D improve beta cell function, optimize insulin sensitivity, and reduce inflammation. A recent study found that subjects with higher baseline vitamin D in the body were at a lower risk of developing type 2 diabetes (by 38 percent!) low level vitamin D.

Benefit 5: Reducing the risk of cancer

Is there anything this vitamin can't do? Research shows that adequate levels of vitamin D in adulthood can significantly reduce the risk of many cancers, including colon, breast, ovarian, and prostate cancers.

Vitamin D is one of the most powerful inhibitors of cancer cell growth and also reduces the risk of cancer by increasing calcium absorption and cell differentiation while reducing metastasis (the spread of cancer from one organ to another)

Sources of Vitamin D - Sun and Diet

At this stage in the development of biological knowledge, several sources of vitamin D are known to mankind. At first, only food was classified as such sources, but over time it was discovered that some D vitamins are available to us from only one source - the sun. Therefore, ultraviolet rays are vital for the human body.

Based on this, one can observe a general lack of vitamin D for a person - a resident of the northern, "cold" countries and continents. This is especially true for places where solar activity does not exceed several months of the year. But here, too, not everything is so clear-cut. People of the Negroid race, unlike Europeans and other races (with more fair skin), even despite the long solar activity during the year characteristic of their countries, are less susceptible to the synthesis of vitamin D by exposure to ultraviolet radiation on the skin. Therefore, for all of us, regardless of skin color and climate zone, it will be useful to know about foods that are sources of D vitamins and can compensate for the lack of sunlight.

So, some algae and fish that feed on them (especially fatty varieties) contain a large number of vitamins. But to get daily dose, 400 IU of vitamin D, you need to eat 150 grams of salmon or 900 grams of cod, which, firstly, is quite expensive for the average person, and secondly, modern farms use feed with antibiotics and additives that can do more harm than good.

Much less vitamin D is found in butter (up to 35 IU per 100 g), cheese and other dairy products (up to 4 IU), eggs (25 IU), fish roe, meat (13 IU). Natural products that contain ergocalciferol are forest (rather than artificially grown) chanterelles and some other mushrooms.

The main method of industrial synthesis of vitamin D (ergosterol) is its isolation from yeast.

As you can see, milk has a small amount of vitamin D, it is much easier to get it from other foods. That is why, in some Western countries (for example, the USA), knowing about the need for food “compensation” of vitamin D, dairy products are enriched with ultraviolet rays using special devices. This practice has existed for several years, but in the CIS countries it is not yet widespread. Vitamin D deficiency can be compensated by plant food. But in connection with a small amount vitamin in such products and their meager assortment, it should be understood that it is necessary to supplement the norm of vitamin D with ultraviolet light. If for some reason this is not possible, and the state of health is deteriorating, you should seek advice.

Vitamin D (calciferol) content in some foods

The norm of vitamin D

The average daily intake of vitamin D and its active forms is 10-15 mcg or 400-600 IU, the maximum allowable intake is 100 mcg.

Vitamin D levels by age

The US Endocrine Society also states 600 IU per day for adults, but notes that more may be needed to increase blood levels of vitamin D above a certain range.

Meanwhile, other independent organizations list even higher amounts of the nutrient. For example, The Vitamin D Council lists 5,000 IU of vitamin D3 per day.

Regardless of the debate, everyone needs calciferol, but certain factors can affect the daily recommended amount:

• Daily allowance for babies. The recommended adequate nutrient intake is 400 IU (10 mcg) per day. Because mother's milk contains 25 IU or less per liter, it is important to ensure exposure to sunlight or supplemental vitamin D intake in the diet. Nutrient deficiency can lead to the development of rickets, cause growth retardation.
• Daily intake of vitamin D for children and adolescents. Although the recommended dose (RDA) of the nutrient is 600 IU (15 mcg), observational studies suggest that more high levels vitamins may help prevent the development of type 1 diabetes in children. It is important to consult a doctor if the child needs an additional amount of calciferol.
• Daily intake of vitamin D for adults. Although the nutrient intake (RDA) is 600 IU per day, a number of factors can affect the recommended intake. You should consult a doctor if the level of calciferol in the body is sufficient.
• Daily dose of vitamin D for the elderly. The recommended nutrient intake for people 70 years of age and older is 800 IU. As a person ages, the human body does not synthesize and absorb vitamin D as efficiently. This can lead to an increased risk of osteoporosis, among others. potential problems with health.
• Norm for pregnant and lactating. The daily dose for these groups is 600 IU. Pregnant women need vitamin D for bone health, immunity, cell division, it can prevent such dangerous complications pregnancy, like preeclampsia. In breastfeeding mothers, calciferol promotes healthy development baby's bones.

Vitamin D deficiency

Vitamin D deficiency is accompanied by fatigue, lack of normal appetite and a decrease in human body weight, feeling unwell, sleep problems, frequent fractures and difficult recovery period. Most often, the elderly suffer from its deficiency, which they spend most of their time at home and are at risk. More than 80% of elderly patients treated in a hospital suffer from osteomalacia and osteoporosis. The risk group also includes residents of the North, people with dark color skin and pregnant women. Residents of large metropolitan areas, due to the sad situation with the environment and increased density modern buildings are also at risk.

Vitamin D deficiency during pregnancy, consequences, prevention

One thing links children's nutrition and vitamin D unpleasant disease- rickets.

It is determined by a number of symptoms, such as:

• slow process of closing the fontanel,
• teeth erupting slowly
• irregular structure of the skull, the so-called "square head",
• facial skull changes
• deformity of the pelvis and curvature of the legs occurs,
• deformed chest,
• such manifestations of violation are noted nervous system like sleep disturbance, nervousness, increased sweating in which sweat has a sour smell.

In order to prevent vitamin D deficiency, it makes sense for pregnant women to make changes in their usual diet, eat foods rich in vitamin D and take short walks every day in sunny weather. Introducing additional intake of vitamin D from outside into your diet is worth it only after a full-time consultation with a doctor and a blood test.

Excess, overdose of vitamin D

An excess of vitamin D is extremely dangerous for human health. It leads to an increase percentage calcium in the blood, as a result, the process of ossification begins. Blood carries excess calcium to other organs of the kidney, lungs, heart. The human skeleton becomes more fragile, the metabolism in human body.
Usually, the effect of excess occurs in babies whose mothers, without a doctor's prescription, independently increase the dose of a vitamin D preparation, which can lead to the development of the "failure of prosperity" syndrome.

Main symptoms:

• inadequate weight gain
• slowdown in growth and development,
• irritability,
• decrease in appetite.

Exceeding the prescribed dose of "Vitamin of the Sun" is as dangerous as its lack.

Symptoms of an excess of vitamin D in the human body:

• increased urine production
• intense thirst, not caused weather conditions or ingestion of spicy and salty foods,
• nausea,
• constipation,
• weight loss,
• persistent increase in blood pressure.

Too much can even lead to death. It causes diseases such as kidney failure, acidosis, hypercalcemia. Hypercalcemia is usually accompanied by a sharp seizure activity, muscle spasms, calcium deposits in body tissues.

Indications for taking vitamin D

Indications for taking vitamin D are:

• bone fractures;
• osteomalacia;
• hypo- and avitaminosis D (rickets);
• osteoporosis, senile and while taking corticosteroids;
• hypocalcemia, hypophosphatemia;
• osteomyelitis (with inflammation of the bone marrow);
• delayed formation of callus;
• osteodystrophy of renal genesis;
• hypoparathyroidism and hyperparathyroidism with osteomalacia;
• lupus erythematosus predominant lesion skin;
• chronic gastritis with achlorhydria;
• chronic enteritis with malabsorption syndrome (including celiac disease, Whipple's disease, Crohn's disease, radiation enteritis);
• enterocolitis occurring with osteoporosis;
• chronic pancreatitis with secretory insufficiency;
• tuberculosis.

It is also advisable to use when:

• arthritis;
• hemorrhagic diathesis;
• hay fever;
• psoriasis;
• tetany caused by dysfunction of the parathyroid glands;
• in peri- and postmenopause;
• to increase the immune properties of the body.

Interaction and compatibility with other elements

Vitamin D promotes the absorption of calcium, as a result of which, due to its excess, iron deficiency in the blood can occur. Also important is the effect of vitamin D on the absorption of magnesium. At the same time, due to a lack of vitamin D, the mechanism of action of calciferol may be disrupted. That is why it is very important to follow a balanced diet. After all, an overdose, like a deficiency, can cause serious violations and even cause deaths from the heart and kidney failure. It is easier to comply with consumption norms than to correct mistakes later, sometimes fatal.

Little known interesting facts

Behind last years scientists have uncovered many D-secrets and, by thoroughly studying calciferol, have learned a lot of interesting things about this vitamin. For example, few are aware that a lack of calciferol can cause schizophrenia or cause seasonal depression. And to saturate the body with vitamin D, black people require 20 times more sunlight than fair-skinned people.

An overdose of the vitamin through the skin is impossible - a certain amount of the substance is produced on the human body, regardless of the time spent under the rays. It is enough to take 2-3 sunbaths weekly in order to reduce the risk of diabetes and certain types of cancer by more than 2 times.

In the countries of the North, a solarium will serve as an alternative to natural sunbathing - it stimulates the production of vitamin D by the skin under the influence of ultraviolet rays. In addition, residents of the northern territories are more at risk of cancer than the inhabitants of warm countries. This is due to the level of obtaining vitamin D from the outside. Tanned and old skin is not able to synthesize vitamin D. And for a healing tan, 15 minutes is enough - the rest of the time spent under the scorching rays is useless for health.

Vitamin D requires fat to be absorbed. This axiom also applies to the skin. Therefore, before taking a sunbath, you should not wash off sebum from yourself, just as you should not take a shower immediately after tanning, it is better to wait 15 minutes.

Natural antioxidants act as sunscreens without interfering with skin synthesis of vitamin D. Such properties are possessed by blueberries, pomegranates, acai fruits.

Rural children are less likely to suffer from vitamin D deficiency - the atmosphere in villages is cleaner than in industrial cities, which allows more easy penetration ultraviolet. Vitamin is worse absorbed by the body with diseases of the kidneys and liver. Daily intake of fortified milk will help to maintain the minimum level of calciferol necessary for an adult organism.

Drinking tea and coffee in large quantities "deplete" the body's vitamin reserves.

If the diet has been balanced for a long time, then the reserves of vitamin D accumulated in the liver will be enough for the body for 6 months.

Calciferol has the properties of a vitamin and a hormone, the structure of which is similar to steroid hormones especially testosterone. It turns out that “washing” cats is also associated with a D-substance: animals lick off a vitamin produced on their skin.

Vitamin D, which is so necessary for children, and adults, is not as simple as it might seem. And scientists are still arguing - is it enough in the summer to just get sunbathing, to provide children's body daily dose of vitamin D.

All mothers know that vitamin D deficiency causes rickets in children, and this is a scientifically proven fact. But it turns out that its meaning is much wider - since without this vitamin calcium is not absorbed, a logical conclusion follows - bones, teeth and all tissues that require calcium suffer from a lack of vitamin D. Vitamin D is involved in lipid metabolism, preventing obesity, reduces the risk of oncology ((breast, rectal, prostate cancer), with the exception of skin cancer, alas. Helps maintain immunity at the required level. Vitamin D receptors are found in almost all tissues of the human body .

Sources of Vitamin D

Group biologically active substances, discovered in 1922, includes several subspecies, including cholecalciferol, which is synthesized in our skin under the influence of ultraviolet rays from provitamin D3, and ergocalciferol, which comes from food with vitamin D2. Cholecalciferol is absorbed much better and since it is fat soluble vitamin accumulates in the body and is consumed throughout the year.

Everyone knows foods rich in vitamin D, but I remind you:

• Fish fat
• Fatty fish varieties
• Cod liver
• Fatty dairy products butter, sour cream, cheese
• Egg yolk
• Forest mushrooms (chanterelles)
• Yeast

But it is worth considering - the amount of ergocalciferol in products is completely insufficient and its deficiency is ensured without sunlight.

What interferes with the production of vitamin D

In order to get the required dose of vitamin D, you must follow certain rules, after all, it has been proven that there are too many factors that can interfere.

1. So it is reliably known that provitamin D is produced with maximum intensity at a length of sunlight of 280-315 nm, which they reach during the zenith - that is, in our latitudes this time is from about 11:00 to 14:00. Of course, at such hours it is completely unacceptable for children, especially small ones, to be in the open sun. But it is during this period that a few minutes are enough to get a daily dose of the vitamin.
2. Since ultraviolet rays do not penetrate any materials, if the child is in the shade of trees, walks in clothes when most of the body is covered, covered with even the thinnest sheet, or looks at the sun through closed window cholecalciferol is not produced.
3. Full cloud cover reduces impact ultraviolet radiation by 50-60%. But it does not exclude at all, it just takes more exposure time
4. Skin color also matters - in fair-skinned children with a small amount of melanin pigment, vitamin D is produced faster, dark-skinned children need more sunlight for a sufficient amount of cholecalciferol.
5. Interferes with the production of vitamin D anyone with a protection level (SPF) greater than 8, and for children it is recommended to use much more powerful protection.

Thus, it turns out that it is difficult to say for sure how long a child needs to be in the open sun in order to fully provide him with vitamin D. How to name the amount of vitamin D that is produced in 5 minutes is very individual and depends on many factors. In any case, the time from 11 to 14 is not suitable for sunbathing for the smallest, and for older children, such a sun is quite dangerous. What to do?

Health care is on the rise these days. Humanity has begun to think more about the presence in the body of certain vitamins and minerals. Recently, vitamin D has become popular. It is also called sunshine vitamin. But not everyone knows why and in what quantity we need it. AND main question: where is vitamin D found and how to replenish it?

What vitamin does the sun give

Nature gives us warm weather and bright sun. And this is far from easy. Everything has its own pattern and sequence. Under the influence of a bright star, complex processes in the human body.

Vitamin D refers to a group of biologically active substances. They play an important role in various processes of the body, the formation of which occurs under the influence of ultraviolet rays. That is, vitamin D is a vitamin that is produced in the sun. It can also enter the human body with food.

D for the body:

• this vitamin regulates metabolic processes calcium and;
• develops and strengthens immune forces;
• vitamin D is involved in the fight against infectious diseases;
• prevents the development of diseases associated with cardiac activity;
• reduces the risk of a number of cancers;
• strengthens the nervous system;
• prevents the development of diabetes;
• creates favorable environment for tissue and cell growth.

The D vitamins are a very important part of the human diet. It performs many functions. The presence of the solar vitamin in the body is very important. After all, without it, neither calcium nor phosphorus is absorbed. Thus, the proper functioning of the whole organism as a whole is disrupted.

The main task of vitamin D is to ensure normal growth.

And also it actively influences:

• proper development of the skeletal system;
• lack of formation of rickets and osteoporosis;
• normalizes blood pressure;
• governs correct work thyroid gland.

This is the kind of vitamin that is produced as a gift of nature, which must be used not only for pleasure, but also for your own health.

How to Get Vitamin D

The vitamin received from the Sun is also interesting in that it comes to us with food. That is, these factors can be supplemented or interchanged.

In addition to the Sun and certain foods, the formation of vitamin D in the body is facilitated by:

• massage;
• application contrast shower or air.

Must comply correct ratio sunbathing, physical manipulation and proper nutrition. In this case, the vitamin that the Sun gives will be supplied to the body regularly in full. And its lack will not overshadow life.

Vitamin D and the Sun

The sun can be considered the most important source of vitamin D. It is recommended to be under its rays more often, but not in the middle of the day. The benefits will be from sunbathing within reasonable limits, of course. There is no need to spend all day outside. It is enough to take sun baths 2-3 times a week for 15-20 minutes.

If a person receives the required dose of ultraviolet radiation, then vitamin D is synthesized in the required volumes.

When getting a vitamin from the Sun, what factors should be considered:

• time of year and day;
• the percentage of melanin in the skin;
• age and weight;
• weather;
• the use of various creams;
• place of stay.

Warm seasons are considered the best conditions. In the morning or evening, exposure to the Sun without a protective cream. An important point is environmental friendliness. It is unlikely that you will be able to recharge your solar vitamin in an urban environment. Therefore, periodic trips to the countryside to the country house, forest or pond are needed.

Lack of vitamin D in the body

Vitamin D deficiency is a fairly common phenomenon. On this moment it affects about a billion of all mankind. This is quite a large number. The main risk group includes children and the elderly.

Most frequent consequences vitamin deficiency, which gives the Sun:

1. The development of rickets in children at an early age.
2. The risk of osteoporosis increases.
3. There are diseases of the liver and intestines.
4. Men may have problems with potency.
5. There are problems with obesity.

Avitaminosis is manifested by the following symptoms:

• there is a suppression of appetite and, as a result, weight loss;
• having problems falling asleep;
• visual problems appear;
• increased bone fragility;
• in children, deformity of the limbs occurs.

If a combination of several signs is observed, it is worth immediately sounding the alarm. The sooner a problem is diagnosed, the easier it will be to correct the situation.

vitamin in food

Of course, walking fresh air- This is good. But don't forget about proper food. The vitamin that the Sun gives a person can be replenished with the following products:

• pork liver, beef and sea fish;
• fatty fish;
• pork and lamb;
• eggs;
• fatty dairy products;
• yeast;
• seaweed.

These products are in moderate amounts will only benefit.

Risk group

There are various reasons, on which you can not be on the Sun. For example, it is contraindicated in cancer patients. Less sunbathing is for people with oncological heredity, as well as light-skinned.

If the Sun is contraindicated, or for some reason it was not possible to bask under its rays in the summer, then the alternative would be to take vitamin preparations, the use of which is better to consult a doctor. It must be understood that an overdose of this substance is very dangerous.

Vitamin overdose

It happens that a person independently decided to improve his health and began to take vitamin preparations, but did not take into account all the components: the frequency of exposure to the Sun, the level of vitamin D in the body, the use fatty foods in large quantities. In this case, an overabundance is possible.

The main symptoms of a vitamin overdose, which gives the Sun:

• poor sleep and irritability;
• sharp headaches;
• unstable blood pressure;
• frequent joint and muscle pain;
• vomit;
• body dehydration.

Occurs very often hormonal disbalance. The body stops listening. Often, an overdose of a vitamin is much worse than its lack.

Delusions

Many may conclude that you need to sunbathe more often and more. But everything is good in moderation.

It must be understood that excessive exposure to the burning Sun without protective equipment won't do any good. But it can do harm. The tan itself doesn't affect anything. But the stronger it is, the lower the skin's ability to reproduce the vitamin.

Many are mistaken that this substance can be obtained by basking in the Sun in the office room. Window glass does not transmit ultraviolet spectrum.

Some people try to replace sunbathing with a solarium. And there is no definite answer here. Some are of the opinion that artificial light is safe, while others argue that tanning beds were originally designed for medical purposes only. And you need to expose the body to ultraviolet rays strictly under the supervision of health workers.

Vitamin D is one of the sunniest and most the right substances. Therefore, do not deny yourself walks in the fresh air. It is very useful to walk in silence and think about the good. And you can have a great time with your loved ones and relatives in nature. By taking care of your health, you can avoid many unpleasant consequences.

Vitamin D is needed to maintain good condition bone tissue of the body. But we get this vitamin from the outside, and it is very often not enough, and then health problems arise. Therefore, it is worth learning more about vitamin D.

Vitamin D in foods

Children used to be given fish oil to prevent rickets. Typically, this fat is very rich in vitamin D: 100 g of cod liver oil contains 1000-2000 IU. IN oily fish contains from 100 to 300 IU of this vitamin, so it is enough to eat about 200 g of salmon or sardine per day to satisfy the body's need. There are foods with a very low vitamin content (from 70 to 100 IU), including mushrooms, duck, cheese.

Vitamin D and the sun

The process of formation of vitamin D is complex, but it is already known for a long time. Under the influence of b-type ultraviolet rays (UVB), derivatives of this vitamin begin to be produced in the skin, and through the kidneys and liver, the formation of already active form vitamin D.

Thus, the sun is our main "supplier" of vitamin D. In summer, in the bright sun, which is at its zenith, if the legs and arms are bare and exposed to ultraviolet radiation, we easily get about 3000 IU, which are deposited in order to then satisfy the body's need for several days.

But in fact, not everything is so simple, because the sun is not always at its zenith, and we are not always undressed to get such a dose. But in any case, experts say that from 50% to 90% of the need for vitamin D is covered by solar radiation. Only it does not work if the skin is protected by clothing or cream with SPF.

Why you need vitamin D

This vitamin controls the process of bone formation in the body throughout life from birth. In addition, it affects the functioning of the sexual, immune system on the condition of the skin. Numerous studies have been conducted that have shown that vitamin D is vital for all cells, if its deficiency is suddenly detected, the body may fail.

Consequences of vitamin D deficiency

For several years, studies have been conducted that have proven how important vitamin D is for the body. Its deficiency can cause disease of cardio-vascular system cause diabetes , autoimmune diseases, For example, rheumatoid arthritis, multiple sclerosis and even some types of cancer (prostate, colon, breast cancer).

It has been proven that mature women who suffer from vitamin D deficiency have less developed memory and a high risk of macular degeneration. The lack of this vitamin contributes to the occurrence of seasonal depression, which manifests itself in the autumn-winter period.

lack of sun

Some scientists argue that diseases of the cardiovascular system, cancer of the breast, intestines and prostate are more characteristic of residents of the countries of the northern hemisphere than the southern. They are also more prone to seasonal depression. And the difference between the two hemispheres is that the northern hemisphere has much less sun.

People who actively prevent skin cancer by smearing themselves head to toe sunscreen, at the same time deprive themselves of vitamin D, because such drugs block b-rays, which stimulate its production.

It is true that excessive sun exposure can cause skin cancer, but in this case this refers to long-term sunbathing, which is repeated for many years from year to year. This is confirmed by scientists from National Institute cancer research (USA). And you really need to protect your skin from UV damage by using sunscreen. But in this case, the best is the enemy of the good, because if you do not allow the sun's rays to reach the skin at all, then there is a risk of getting a vitamin D deficiency.

Don't deprive yourself of the sun entirely. If possible, take a walk for a while, exposing your legs or arms to the sun. But at the same time, be careful: it is better not to do this during lunch hours, when the sun is very active and the risk of burns is high. The same rules apply for children.