Sun what vitamin gives through sunburn. The sun and vitamin D are the key to health. vitamin in food

And in the dark and cold winter months, when there is so little sun and colds and viral diseases waiting around every corner, and in hot sunny summers, when it is so easy to burn out in the scorching sun, the most important factor for maintaining immunity is high level vitamin D in the body, which directly depends on the amount of ultraviolet radiation received. Numerous studies are now being conducted on this topic, which often refute data that were previously considered indisputable facts and, as a result, recommendations are often directly opposite to those given before. You've probably heard some vague advice, such as being in the sun for "a few minutes every day." But they are too general and vague to be useful. The amount of sun you need to meet your vitamin D needs varies greatly depending on your location, skin type, time of year, time of day, and even atmospheric conditions.
Myths about tanning:
1. Sunbathing Best before 12 pm and after 3 pm.


4. With the help of any solarium, you can gain the missing vitamin D in the winter.

1. Sunbathing is best before 12 noon and after 3 pm.
The optimal sun exposure time for vitamin D production is, as far as possible, around noon, between about 11:00 am and 3:00 pm.

The fact is that the region of ultraviolet radiation includes waves of various ranges, which are conditionally divided into three groups:

UV-A (UVA) (315-400nm)

UV-B (UVB) (280-315nm)

UV-C (UVC) (100-280nm)

UVA and UVB rays are able to pass through the ozone layer to reach our skin, but they are vastly different when it comes to their individual characteristics.

UVB rays:

Responsible for starting the production of vitamin D in the skin.

They cause sunburn.

Cannot penetrate glass or clothing.

Active only in certain times year and day.

UVA rays

Do NOT induce vitamin D production in the skin.

Does not cause sunburn.

Penetrate deeper into the skin than UVB rays and therefore cause premature aging, discoloration, and wrinkles.

They are able to penetrate glass and clothing, and are active throughout the year all day.

Between 11:00 am and 3:00 pm, short sun exposure is enough to get vitamin D, because UVB rays are most intense at this time. But you need to be very careful with the amount of time you spend in the sun. Remember that this exposure is enough for the skin to become a slightly pink hue. For some, this will take a few minutes, and for someone it may take an hour or more, after which the chances of burning out only increase, and this, definitely, I would like to avoid. The fact is that the body can only produce limited quantity vitamin D per day. After it reaches its limit, further exposure to the sun will only bring harm and damage to the skin.
When the sun goes down to the horizon, much more UVB rays are filtered out than dangerous UVA. It is also possible that the sun at 9 am or 5 pm will reduce vitamin D levels, as there is evidence that UVA destroys it.
So if you want to get out in the sun to optimize your vitamin D production, and minimize your risk malignant melanoma- the middle of the day is the best and safest time.

2. To maintain the required level of vitamin D in the body, it is enough to expose your hands and face to the sun 2-3 times a week for 5-15 minutes during the summer months.
It is generally accepted that for most people, 15 minutes of exposure to UV light is enough to form as much vitamin D in the skin as, according to the recommendations of doctors, should be produced daily to maintain health.
However, once you get a tan, you need to spend a lot more time in the sun. If you have dark skin, it can take two to six times longer (up to an hour or two) to reach the equilibrium point, depending on the pigmentation. People with fair skin. those who live quite far from the equator (for example, in the UK or in the northern United States, central Russia) need at least three of the 20-minute sessions per week, in bright midday sunlight and with a minimum of clothing. A dark-skinned person, of course, must be exposed to the sun much more, and more often, to get the same effect.

This information is just beginning to filter through the media, so it's important to emphasize this point.

3. When going out into the sun, you should always use sunscreen.
Keep in mind that using sunscreen largely negates your efforts to metabolize enough vitamin D. It is advisable to make sure that you do not have a vitamin D deficiency before resorting to sunscreen of any kind.

But, if you really need some form of protection when you're out in the sun for extended periods of time, it's best to use light clothing to cover exposed areas, or look for safer, natural ones.sunscreens that do not contain petroleum products.
It's also important to remember that if you're using the sun or a safe tanning bed to get your vitamin D, keep in mind that it takes about 48 hours for vitamin D to fully pass from the surface of your skin into your bloodstream, and you can easily wash it off with soap and water. water. Thus, it makes sense to limit ourselves to the minimum hygiene procedures for at least 48 hours so that all vitamin D is absorbed. As strange as it sounds, washing can negate all your efforts.

4. With the help of any solarium, you can gain the missing vitamin D in the winter.
AT winter time many people use a tanning bed to prepare their skin for the summer sun, maintain their vitamin D levels, avoid winter depression, and just for beauty. If someone is doing this in a commercial location, remember that it's a good idea to ask the owners what kind of lamps they're using. There are solariums that use both UVA and UVB radiation in different proportions, and some use only UVA. As noted above, UVB radiation is necessary for the production of vitamin D. In natural sun, the ratio of UVA to UVB is approximately 2.5-5.0% UVB, respectively, being in a tanning bed with 5% UVB and 95% UVA is about the same as if you were in bright sunlight in the middle of the day and this enough to get the right dose of UVB radiation, and therefore vitamin D.

In recent years, it has become more and more obvious that even taking into account the recommendations of scientists and doctors, it is not so easy to understand what measures need to be taken in order to. on the one hand, due to excessive caution, do not deprive yourself of what the body needs to maintain good health, and on the other hand, do not harm yourself by neglecting dangerous factors.
The exact data that OpenWeatherMap delivers to the IT market using the most modern technologies(eg Big Data) can be and, in many areas already are, the basis for products that can help people get accurate predictions and recommendations to maintain and protect their health.

For the past couple of decades, the scientific world has been fascinated by vitamin D. Perhaps a revolution of no lesser magnitude occurred when Linus Pauling formulated his theory about the benefits of vitamin C. Some enthusiastic scientists even claim that Pauling said everything correctly, only he made a mistake in the letter.

Thousands of studies show that vitamin D deficiency increases the risk of cardiovascular disease, multiple sclerosis, some types of cancer and even psoriasis. Health authorities say that the statistics are not so clear, so it is too early to recommend vitamin D as a curative and preventive agent.

The only thing that can be said with certainty is that there is no pharmacological lobby and special interests behind these studies. After all, sunlight on Earth is completely free, and moderate and safe exposure to its rays is quite capable of providing the recommended level of vitamin in the blood.

What is it and how does it work

Vitamin D is a fat-soluble inert substance (prohormones), from which the body itself synthesizes special hormones. The first substance is called D 3 , or cholecalciferol, and it can be formed under the influence of ultraviolet B (wavelength 280-320 nm) or come from animal food. The second - D 2 , ergocalciferol - is not synthesized under the action of light, but enters our body only with food, for example, with some types of fungi (Fig. 1).

The precursor D 3 is formed in the epidermis of the skin from cholesterol under the influence of UV rays, isomerizes into D 3 at body temperature, then binds to a special protein and penetrates into the blood, and is transferred with the blood to the liver. Vitamin D (both D 2 and D 3) from food also gets there. In the liver, D is converted to 25-hydroxycholecalciferol (abbreviated as calcidiol, or 25(OH)D). At the next stage, in the kidneys, calcidiol finally turns into active hormone- 1,25-dihydroxycholecalciferol (calcitriol, or 1,25(OH) 2 D; see Fig. 2). However, to assess whether a person is deficient in vitamin D, blood levels of the precursor of the active form, calcidiol, are measured. The fact is that even when there is not enough vitamin D in the body, there can be a lot of calcitriol in the blood serum, so its level cannot be a true indicator.

The most important function for which vitamin D is responsible is the formation and renewal of bone tissue, because without it, neither calcium nor phosphorus is absorbed in the body. But he also has many other tasks. Among them are the regulation of cell division and control of cell differentiation, the regulation of the immune response and the secretion of hormones. Where does this vitamin get such opportunities from?

In the cells of many organs and tissues, in the nuclei and on the membranes, there are calcitriol receptors (they are called VDR, from vitamin D receptor). 1,25(OH) 2 D attaches to them, activates these receptors, and they, in turn, activate the genes encoding certain proteins - the synthesis of these proteins is turned on. VDR receptors are present in the cells of the brain, heart, skin, mammary glands, intestines, genital organs - more than 40 organs and tissues in total. There is evidence that 3% of the human genome is regulated by the hormone 1,25(OH) 2 D. Perhaps this explains its diverse and diverse action (Fig. 3).

Calcitriol may also act outside the genome. For example, its attachment to a receptor (in this case, most likely, to the membrane, and not to the nuclear one) opens ion channels or changes the activity of intracellular kinases - enzymes that attach a phosphorus group to proteins and thereby trigger a cascade of regulatory reactions (about similar reactions "Chemistry and Life" featured in #11, 2012, in a report on Nobel Prize for research on G-protein coupled receptors). It's over fast way regulation than through genes - from seconds to tens of minutes.

A very simple solution

Employees of many research centers today are trying to answer the question: does a constant deficiency of vitamin D really increase the risk of not only osteoporosis, but also cancer, diabetes, psoriasis, multiple sclerosis and others terrible diseases? The assumption that sunlight can protect against cancer was first formulated in 1937 by Sigismund Peller and Charles Stephenson. Then, in 1941, they found that cancer mortality depends on the latitude of residence: the closer to the equator, the fewer people die from cancer.

In 1980, Cedric Garland and Frank Garland published in the magazine " International Journal of Epidemiology» the results of their research - a sufficient amount of vitamin D in the body significantly reduces the risk of developing colon cancer. This was also confirmed by other researchers. There are also statistics, according to which residence in countryside and moving to more southern latitudes also reduce the risk of getting cancer.

Since the late 1990s, the number of publications on this topic has exploded. Many of these studies have confirmed that a sufficient amount of 25(OH)D (not less than 75 nmol / l) in the blood serum reduces the risk of breast, ovarian, prostate and intestinal cancer. However, in some experiments, the expected effect did not work. Even a person far from science understands that it is difficult to collect such statistics. Need to find volunteers - more or less healthy people of the same age, divide into groups, give them various doses vitamin, and the placebo control group and observe them for a long time. Oncological diseases, fortunately, do not develop quickly, and we cannot predict their appearance - someone will be diagnosed in a year, someone in ten years, and someone will not find anything during the study period. And if some of the participants in the study developed cancer two years later, even while taking enough of the vitamin, does this mean that the vitamin did not help? What if these people lacked him for the previous 25 years?

Many of the results were the result of clinical trials not of vitamin D itself, but of calcium in combination with vitamin D (after all, it is known that not only women after menopause, but men also develop osteoporosis at a certain age). In this case, the experiment was originally aimed at something else (to prevent age-related fragility of the skeleton), and it is also quite difficult to isolate the effect.

The numbers published in the review "Vitamin D for Cancer Prevention: A Global Perspective" by Garlands et al (see link at end of article) are impressive. People who spent enough time in the sun or took calcium and vitamin D by mouth (1,100 IU of vitamin D and 1,450 mg/day of calcium) had a 50 percent or more reduced risk of prostate, breast, or colon cancer.

It has even been calculated that every 25 nmol/L increase in blood 25(OH)D reduces the risk of cancer by 17%. Scientists also note that with sufficient levels of the vitamin, tumors, even if they occur, are much less aggressive and easier to deal with.

The reviewers went so far as to suggest revisiting vitamin D intake (we’ll talk about the norms a little later, but now they are significantly lower) and give everyone 2000-4000 IU of vitamin D per day, depending on latitude. For North America, the recommended dose was 2000 IU of the vitamin, which, according to the authors, would significantly reduce the number of patients with breast and colon cancer. Recall that IU - international unit, or unit of action, is a dose of a vitamin, hormone or other substance that corresponds to a certain biological activity; in many cases IU is more convenient than units of mass. By the way, by the time the review was published in 2009, 3,000 studies had been completed and published in biomedical journals, including 275 epidemiological studies on the association of vitamin D and its metabolites with oncology. According to the authors, only some of them did not confirm this inverse relationship.

With epidemiological studies, as well as with statistical ones, not everything is going smoothly. They show that in more northern latitudes, the mortality rate from cancer is generally higher than in southern latitudes, that is, more people die from this disease - for every 10 ° of latitude, the annual production of the vitamin increases by 50%. (Of course, speaking here about the north and south, we mean ours, North hemisphere.) But if we study the statistics of death within one country, distributed over the seasons, then its connection with the sun is not always found. In general, in many northern countries more people die during the winter season, but not in all. Also, a clear dependence of death on specific diseases (cancer, cardiovascular diseases, etc.) by season and latitude is not everywhere visible. For example, for Norway it is not confirmed that more people die of cancer in winter, and there are more of them in the north of the country. But the researchers found an explanation: in the north they eat a lot of oily fish, and this compensates for the lack of UV illumination. On the other hand, Norwegian scientists have found another obvious relationship: in winter and spring, most cancers are detected.

What is the possible defense mechanism vitamin D? About ten mechanisms have been proposed, and all of them are somehow connected with it not very widely. famous action on a cell. Solar vitamin regulates growth, cell differentiation and apoptosis, inhibits vascular growth, has an anti-inflammatory effect, etc. Indeed, in many studies, 1,25(OH) 2 D inhibited the growth of tumor cells, in experiments in vivo and in vitro in rats inhibited vascular growth factor and inhibited prostaglandin synthesis.

Now even attempts are being made to treat (or at least make less aggressive) some tumors with vitamin and its derivatives. Now there are more than one hundred clinical trials, so perhaps something will become clear soon. The Charite clinic (Berlin, Germany) also undergoes clinical trials for the treatment of multiple sclerosis with vitamin D.

How much should it be

Let us immediately state that different countries accepted different norms. According to the protocol adopted in 2010 by the Institute of Medicine of the US National Academy of Sciences ( Institute of Medicine US), if the level of 25(OH)D in the blood serum does not reach 50 nmol/l, this is a vitamin deficiency, if 50–74 nmol/l is a deficiency, and values ​​from 75 nmol/l and above are considered normal. Rickets and osteomalacia (softening of the bones) begin at values ​​less than 25 nmol/L.

In principle, a person who eats a varied diet regularly and for a long time outdoors, should not be deficient in vitamin D (the exception is people with dark skin, in whom melanin interferes with the production of the vitamin). But that's the problem, that modern look life involves enclosed spaces and monotonous food on hastily. Therefore, many people on Earth today have too low serum levels of calcidiol - by some estimates, a billion people, including more than half of women who have reached menopause.

According to large-scale measurements, a third of the US population is at risk of inadequate intake, that is, they have less than 75 nmol / l of the vitamin. The most surprising thing is that even in sunny countries - in India, Pakistan, Iran, China - 60-80% of the population does not reach this indicator. The main reasons are long stay in enclosed spaces, dark color skin, insufficient amount of fish in the diet.

Food is pretty simple. The main source of vitamin D 2 , or ergocalciferol, is some mushrooms. Not mushrooms from greenhouses, but “wild” mushrooms: various sources call shiitake mushrooms, white mushrooms. Vitamin D 3 is found in animal products. There is quite a lot of it in the liver of fish, less in fatty fish, and even less in milk, butter, cheese, egg yolk(see table).

According to current recommendations, a person needs 600 IU per day. This dose can be obtained from food only if you eat only oily fish. And so, in normal life, we get a maximum of 10% of the daily requirement of vitamin D from food. Therefore, we cannot do without the sun.

Sunbathing is needed at the same time quite long. Here is one recommendation: 30 minutes in the sun every day. If you are sunbathing in Spain or California (38° latitude), then 12 minutes of sunbathing a day with 50% of your body exposed will give you 3000 IU per day. Or the minimum erythema dose (MED), that is, exposure to the sun, which gives slight redness skin after 24 hours, is equivalent to the production of 10-20 thousand IU of the vitamin. Naturally, without sunscreens that block its synthesis.

Many readers probably remember that doctors recommend avoiding direct sunlight because of the risk of skin cancer. Today, taking into account the data on vitamin D, it is still advised to take short sunbaths, but the main thing is to eat more oily fish. (And if necessary, take nutritional supplements in winter.)

By the way, since there is very little sun in autumn and winter and the vitamin level inevitably drops, by the end of summer its values ​​​​should exceed 80 nmol / l in order to be enough for the winter. If tanning enthusiasts take this information as a guide, they should keep in mind that many lamps produce a different UV spectrum than that of the sun - UV A (320–400 nm) rather than B (280– 320 nm). Therefore, in the solarium you can get a pretty dark skin tone, but not replenish your vitamin D reserves.

At-risk groups

Who is vitamin D deficient? Of course, the elderly, who rarely go out, the children breastfeeding(if mother does not spend enough time in the sun), as well as to everyone who lives in northern latitudes (to the north of 42 ° - that is, this is both Moscow and St. Petersburg ...). However, not only them. There are people who simply avoid the sun - they protect their skin or consider ultraviolet radiation to be harmful and are afraid of it. And even when we go sunbathing, we habitually take a whole set of sunscreens with us. They really protect the skin from sunburn, but at the same time block the production of vitamin D. As already mentioned, people with dark skin. They take many times longer to produce the same amounts of vitamin D.

And finally (although, perhaps, this should be put at the beginning) - people with overweight. Body mass index (BMI) is calculated as weight twice divided by height in meters (M/L·L, kg/m2). If it turns out 25–30 kg / m 2, then a person overweight, and more than 30 - already obesity. So, the higher this index, the significantly lower 25(OH)D in blood serum: an increase in BMI by one unit reduces the content of 25(OH)D by 0.7–1.3 nmol/l. Statistics state the following: 19% of men and 27% of women with normal weight (BMI less than 25 kg/m2) have vitamin D levels above 100 nmol/l; 75% of men and 40% of women with a body mass index of more than 40 kg / m 2 do not have enough vitamin in winter, and a quarter in summer too; 71% of obese men and 62% of women are deficient in vitamin D (less than 75 nmol/l). We add that by 2015 there will be 2.3 billion overweight people in the world, of which 700 million will be obese.

The reason is clear: vitamin D is fat-soluble, so it is stored in excess subcutaneous adipose tissue and becomes extremely inaccessible. It is estimated that in a woman of normal weight, 35% of vitamin D is distributed in adipose tissue, 30% in blood serum, 20% in muscles, and 15% in other tissues. Overweight women store three quarters of their stock in adipose tissue.

Relentless statistics say that obesity is increased risk get cancer. Not all of its types, in addition, for men and women, the risks differ slightly, but for some positions, the danger increases by almost one and a half times. Why? Presumably, the chain looks like this: first, with excess weight, insulin receptor insensitivity occurs (the so-called type II diabetes). Then adipose tissue begins to actively secrete hormone-like substances adipokines into the blood, inflammation begins, the concentration of estradiol and testosterone in the plasma increases, and at the same time the concentration of globulins that bind them decreases - the process is started. It turns out that obesity, vitamin D content and the risk of getting cancer are closely related (Fig. 4). According to research by Norwegian scientists published three years ago (“ Molecular Nutrition & Food Research”, 2010, 54, 1127–1133, doi: 10.1002 / mnfr.200900512), people with a body mass index close to 45 kg / m 2 are almost twice as likely to develop cancer, and almost 20% of cases are the contribution of reduced vitamin D content. For breast cancer, this contribution rises to 40%, and for colon cancer, almost up to 70%.

What about us, the victims of modern civilization? Although a large number of experts believe that modern conditions the norms need to be reviewed, the authorities of all countries are in no hurry to change. Therefore, if today we look at Wikipedia in three languages ​​- Russian, English and French, we will see that the mechanism of action is described the same, but the texts on the protective role and recommendations are different. While the US FDA and a similar organization in Canada advise not to be tempted by the thought of another panacea, the Canadian Osteoporosis Organization and the Canadian Cancer Society, as well as many experts, believe that there is nothing to wait for and everyone should take from 2000 to 6000 IU per day. Meanwhile, although it seems to be verified that high doses of the vitamin are well tolerated without any consequences, there is evidence that too high levels of vitamin D (more than 150 nmol / l), as well as too low, can also lead to increased risk get some types of cancer and premature aging.

A laudatory ode to the "vitamin of the sun"
Vitamin D was discovered in the 20-30s of the last century, and the first studies have already shown that it is with a lack of this vitamin in children's body diseases such as rickets, bone curvature and spinal deformity are associated. Currently, a whole group of vitamins D is known - D1, D2, D3, etc. The most important of them are D2 (ergocalciferol) and D3 (cholecalciferol), they are very similar in properties and effects on the body, and they are most often combined one common name- calciferol or vitamin D.

Perhaps someone will doubt whether we, adults, should attach such importance to the “children's” vitamin, because the time of formation skeletal system long gone, rickets no longer threatens us. It turns out that vitamin D is not so simple, and it physiological role is not only in the regulation of metabolism in the body of calcium and phosphorus, which is especially important for a growing organism. Intestinal permeability and other minerals (zinc, iron, cobalt, magnesium) depend on vitamin D. It is indispensable in the fight against violations in work and in the battle against infections, helps the smooth functioning of the heart, regulates the activity nervous system. Vitamin D is necessary for normal blood clotting, prevents the development of atherosclerosis, is important for the functioning thyroid gland and normal blood clotting, helps to get rid of many eye diseases. Women with sufficient levels of vitamin D in the blood are less likely to have benign and malignant tumors breast and ovarian cancer.

So, vitamin D is necessary for everyone and always - both in childhood, and in blooming youth, and at the age of elegance, and at sunset. As soon as we stop caring about supplying our body with this vitamin, problems pile up, ranging from aching bones, back pain, and ending with fractures, depression, memory impairment, problems with blood pressure, and you never know what else can happen if you neglect sunshine vitamin.

And the way it enters the body is simple:
- from the outside with food and medicines,
- and production by the body under the influence of the sun. Moreover, about 90% of vitamin D is formed in the body in the sun, while about 10% comes from food.

It is also important to note that vitamin D is fat soluble, it is not washed out of the body with fluid, but rather slowly excreted in the bile, so it is quite possible to store some inactive vitamin D in the liver for several months.

How vitamin D is formed in the skin, or some of the nuances of sunbathing ...
is the main source of vitamin D in the body. Under the sun's rays on the surface of the skin covered with thinnest layer cholesterol-like substance ergosterol and sweat, vitamin D is formed, which is then absorbed by the skin, penetrates into bloodstream and eventually enters the liver, where then, in the course of metabolism, its transformation into active forms begins. Moreover, part of the inactive vitamin D is stored in reserve in special cages liver reticulocytes, which ensures the maintenance of the required level of its active forms in the body for several months. In the liver, the process of converting the so far passive calciferol into the active hormone calcitriol begins and ends in the kidneys, and it is from here that this hormone sets out to fulfill its important mission, controlling the absorption of calcium and phosphorus by the body.

Luckily, our bodies can store vitamin D, so it's important that our skin produces enough vitamin D over the summer to last through the rest of the year.

Sunbathing to replenish vitamin D(and not for chocolate tanning) some features should be considered:

- "sunshine" vitamin is formed when exposed to ultraviolet rays on sebum located on the surface of the skin, so you should not wash it off before sunbathing;

Also, don't be in a hurry to accept. water procedures immediately after sunbathing, allow time for the vitamin to be absorbed into the skin;

They protect us from ultraviolet radiation and at the same time block the ability of the skin to produce vitamin D. Sunbathing without sunscreen within 15-20 minutes in the morning and in the late afternoon, several times a week, according to experts, is able to provide synthesis required amount vitamin D;

The activity of the synthesis process is directly dependent on the intensity of irradiation and inversely on the degree of skin pigmentation, that is, the more you tan, the lower the skin's ability to produce vitamin D.

It should also be taken into account that the skin is able to efficiently produce vitamin D when exposed to ultraviolet rays in a clean atmosphere, so walking through the city streets, over which a haze of dust and exhaust gases hangs, is unlikely to promote health and accumulation of the vitamin.

Give the sun a chance!
And what happens? If we, following the recommendations of dermatologists-oncologists, do not appear outdoors without sunscreen and appropriate clothing, we save ourselves from sunburn, dermatitis, photoaging, malignant neoplasms and at the same time deprive our body of vitamin D that we need so much. our skin is already covered with a chocolate tan and it is not afraid of burns, we no longer use a protective cream so strictly - and our own tan is already getting in the way of vitamin D synthesis.

Let's try to find a reasonable compromise. Moreover, the tan itself, in recent years, is not such a prestigious factor. Thanks to numerous warning publications, excessive tanning is no longer taken as evidence these days. healthy lifestyle life and social status of its owner, but rather as evidence of some ignorance or a frivolous attitude to one's own health.

So, our choice is short sunbathing without protective equipment in safe time days (morning, evening), the rest of the time sunscreen of the desired degree of protection, skin care products and good nutrition.

Alternative ways
The second way that vitamin D enters our body is through food. The main sources are raw egg yolk, cheese, butter, fish liver (especially cod and halibut), fatty varieties marine fish(herring, mackerel, tuna, mackerel). There are also plant sources vitamin D - parsley, nettle, mushrooms, alfalfa, horsetail - however, its content in them is very small.

daily requirement in the vitamin that enters the body with food, approximately 200 international units / ME /, this is if you are daily outdoors under the influence of sunlight for 30 minutes. If sunbathing is not for you, then the norm increases to 1000 IU.

Based on 100 g:
- animal liver contains up to 50 IU of vitamin,
- in egg yolk - 25 ME,
- in beef -13 ME,
- in corn oil - 9 ME,
- in butter - up to 35 IU,
- in cow's milk- from 0.3 to 4 IU per 100 ml.

As you can see, even with a complete diet, the body's need for a vitamin is difficult to fully meet through food. combination of sunlight and right choice menu is the most reliable way to solve the problem.

You can also diversify your diet with foods additionally enriched with vitamin D, these are milk, yoghurts, breakfast cereals, cookies, bread. It is only important to take into account that vitamin D is recommended to be taken together with calcium, because its main function is to promote the absorption of calcium by the body, to regulate phosphorus-calcium metabolism. If calcium is not supplied with food, then it is taken from the bones, and this is a direct path to the development of osteoporosis. Therefore, milk fortified with vitamin D can be considered healthier than fortified bread.

Well, in the cold season, or in the case when the sun is contraindicated for you, you will have to replenish your vitamin D reserves with the help of vitamin preparations. Before deciding on the use of vitamin preparations, consult your doctor. You should not take vitamin D in larger quantities than you need, its excess is just as dangerous as its deficiency.

In the meantime, summer reigns, the sun is shining, think about medicines early, spend more time outdoors, catch sunshine vitamin» all exposed parts of the body, but do not forget about safety rules.

- such a bright nickname, or calciferol, was not accidental. After all, the main way to replenish it in the human body is synthesis in skin cells under the influence of ultraviolet radiation. And as often as we lack the gentle rays of the sun, just as often researchers note hypovitaminosis D among the population of the middle and northern latitudes of the globe. Is it dangerous? And how can you get vitamin D in other ways?

The importance of vitamin D for human health

If life on Earth is impossible without the sun, then without vitamin D it is impossible to perform a number of vital functions in human body. It is most widely known as a means of preventing rickets in infants and strengthening bones in and. It is needed for the full assimilation of the bone mineral in the intestines, maintaining the calcium-phosphorus balance in the blood, mineralization and renewal of bone tissue. But this is only part of the iceberg.

The solar vitamin never ceases to surprise researchers, exposing its new facets. So, scientists have found that almost all tissues and organs have receptors for it, which means that it is involved in their work. So, high sensitivity cells differ in vitamin D immune system– monocytes, macrophages, lymphocytes and dendritic cells. Interacting with them, he manages defensive reactions and helps fight disease. The same applies to cardiovascular reproductive systems, brain, intestines, breast, skin, etc.

A lot of research points to the relationship of vitamin D deficiency with and, heart and, infectious and colds, autoimmune pathologies, obesity and diabetes, depression and dementia, oncology and other disorders.

Along with such data, the prevalence of hypovitaminosis D is especially alarming. Thus, during an impressive 2-year study conducted by the Federal Research Center and Biotechnology, a massive deficiency of vitamin D was revealed among Russians: 80% of the inhabitants of the Russian Federation receive less of it. One of the leading reasons for this is due to low level insolation of the vast majority of Russian territories.

How to get the sunshine vitamin if there is not enough sun?

No matter how diligently you sunbathe in the summer months, if you live higher, that is, north of the 35th parallel, you are provided. So you should take care of replenishing the body with vitamin D from other sources.

Vitamin D plays important role in the work of the immune, nervous, cardiovascular and other body systems.

Irina Zhukova, PhD, dermatocosmetologist

For a long time, vitamin D was “in the shadows” and was considered a drug for the prevention of rickets for children, as well as for strengthening bone tissue in old age. In recent years, vitamin D in combination with calcium has been actively promoted to strengthen bone tissue. But clinical and experimental data of recent years have proven the widest range its effect on the human body. Vitamin D is involved in the regulation of fat and carbohydrate metabolism substances, maintaining normal blood pressure, the prevention of the so-called metabolic syndrome. The role of vitamin D in immune responses, cancer prevention and other aspects of human life has also been proven.

In this regard, large-scale studies have been carried out to assess the content of vitamin D in the body of a modern person. And the results of these studies were very sad.

Humans get their vitamin D from two sources: animals and herbal products containing different forms vitamin D, as well as from the skin, where vitamin D is formed in the upper layers of the skin under the influence of UVB spectrum with a wavelength of 270-315 nm.

The foods richest in vitamin D are fatty fish and canned fish, butter, and eggs. Vitamin D is not destroyed by food storage and cooking and also has a high bioavailability, but its dietary intake is usually so small that it does not meet the needs of the body. And the main source is its synthesis in the skin under the influence of UV radiation. The production of provitamin D in the skin depends on the geography of the place, time of day, ecology and cloudiness of the atmosphere. The required wavelength is present in the solar spectrum characteristic of the tropics; for the spring and summer sun in temperate countries, and is not found in arctic latitudes. The formation of vitamin D almost completely stops in the morning and evening, throughout the day in the winter months at latitudes above and below 35 degrees, as well as in a polluted or cloudy atmosphere. The UVR type B spectrum necessary for a full-fledged synthesis is characteristic of the tropics, while the formation of vitamin D in the skin of Russian residents occurs within about 7 months at the latitude of Sochi, 4 in Moscow, less than 3 (May-June) months in St. Petersburg.

30 minutes- during this time in the summer, a fair-skinned person receives an amount of vitamin D equal to 227 chicken eggs or a pound of cod liver.

6 months the “winter of vitamin D” lasts for residents of Russia, Northern Europe and Canada.

In addition, other factors also influence the production of vitamin D: age, the degree of “openness” of the body, skin color and the severity of subcutaneous fatty tissue. The formation of vitamin D is reduced in the elderly and obese people. The skin pigment melanin, which is formed during the tanning process, is a natural sunscreen, so dark-skinned people need 3-6 times large dose sun exposure to produce the same amount of vitamin D as fair-skinned people. In addition, ordinary windows of houses and cars, clothes and cosmetics with sun protection factors prevent the action of UV-B even in summer.

But excessive inmolation causes the so-called “photoaging of the skin”, and also provokes the development of malignant neoplasms. Therefore, doctors strongly recommend avoiding abuse sunbathing and carefully protect the skin from the sun. And the result of this was, along with the positive phenomenon - the "unfashionable image" of tanning, that people who avoid the sun have an increased risk of developing hypovitaminosis throughout the year. According to the world's leading experts, about a billion people on Earth, children and adults, are deficient in vitamin D.

SO WHY DO WE NEED VITAMIN D?

Vitamin D is most important for the normal functioning of bone tissue. The role of calcium in bone formation is beyond doubt, but, unfortunately, very often even experts forget that with vitamin D deficiency normal exchange calcium is almost impossible. addicting even large quantities calcium in dietary supplements or medicines with hypovitaminosis D not only does not lead to an improvement in the state of bone tissue, but, on the contrary, may be accompanied by the appearance kidney stones and deposition of calcium in the body.

According to statistics, 30% of older people fall once a year, 10% of those who fall have a hip fracture, and every fourth patient with a hip fracture dies within a year after the fracture. In connection with the progressive “aging” of the population, especially in developed countries, this problem is of great social importance. Of great importance are various injuries and in younger people - on slippery sidewalks, during classes various types sports, etc. Regular intermittent intake of vitamin D leads to a reduction in the number of fractures by more than 30%. Moreover, there is not only a decrease in the number of fractures, but (and this sounds fantastic at first glance!) A decrease in the number of falls. Normalization of vitamin D levels results in improved neuromuscular transmission and muscle function, resulting in human body automatically reacts faster to changes in position in space and manages to maintain balance. In addition, vitamin D prevents the decrease in muscle mass and strength characteristic of older people.

The next important aspect of the impact of vitamin D on the human body is its effect on the so-called “metabolic syndrome”, the main manifestations of which are: lipid metabolism disorders, overweight, arterial hypertension, diabetes 2 types. Metabolic syndrome and its consequences such formidable diseases as heart attack and stroke are considered the number one cause of death of modern man. Positive influence vitamin D for various aspects The formation of the metabolic syndrome is confirmed by the results of numerous studies conducted according to all the rules of evidence-based medicine.

Vitamin D provides the human body with a complete immune defense. It is believed that hypovitaminosis D in winter can be one of the main reasons for the seasonality of influenza and SARS. active form vitamin D is one of the effective regulators of the inflammatory process, which is why it positive action with chronic inflammatory processes in osteoarticular system. It is also believed that vitamin D is an unexplored substance that helps to reduce the sensation of pain. A pronounced analgesic effect (more than 90% of patients) from taking vitamin D was noted in patients of all ages with pain in the back, joints, etc.

Vitamin D and doctors did not ignore aesthetic medicine. Vitamin D has a regulatory effect on the functioning upper layers skin and protect it from photoaging. Vitamin D improves condition and function muscular system by stimulating the synthesis of muscle fibers. Normalization of its level leads to an improvement in neuromuscular transmission and muscle function, which has a positive effect on the condition of the face and body, and allows you to deal with flabby muscles of the arms, thighs, and abdomen. In addition, vitamin D supplementation prevents a decrease in the absolute amount with age. muscle mass, that is, it is necessary to maintain muscle strength, endurance and youthful body contours. Nutritionists have come to the conclusion that vitamin D helps the body not only absorb calcium and strengthen bones, but also regulates the formation of adipose tissue.

Women who were found to be deficient in vitamin D weighed an average of 8-9 kg more than those who had sufficient amounts of this vitamin. Why? Doctors suggest: either the vitamin slows down the formation of fat cells, or, conversely, fat cells block vitamin D, preventing its absorption by the body.

Thus, it can be concluded that vitamin D plays an important role in maintaining correct operation immune, nervous, cardiovascular and many other body systems. Low content vitamin D in blood plasma is associated with the development of diseases such as osteoporosis, arterial hypertension, diabetes mellitus type 1 and 2, malignant neoplasms, infectious diseases, periodontal disease.

The need for vitamin D is increased when there is a deficiency ultraviolet irradiation: in people living in high latitudes, residents of regions with high air pollution, working on the night shift or simply leading a nocturnal lifestyle who do not go outdoors. Disorders of the intestines and liver, gallbladder dysfunction negatively affect the absorption of vitamin D. In pregnant and lactating women, the need for vitamin D increases, because. an additional amount is needed to prevent rickets in children.

How modern man fight hypovitaminosis D? The main source of vitamin D is dietary intake as part of traditional and fortified foods or biologically. active additives to food.

There are several pharmaceutical forms of vitamin D preparations. Questions of the duration of courses of administration, optimal dosages are currently being discussed by specialists. In accordance with the Norms adopted in 2008 physiological needs”, children and people of working age should receive 10 micrograms (400 IU) of vitamin D per day, pregnant and lactating women - 12.5 micrograms (500 IU), people over 60 years old - 15 micrograms (600 IU).

30% – This is how much the number of fractures decreases with regular intake of vitamin D.

10 mcg (400 IU) - such is the generally accepted daily rate vitamin D for children and people of working age.

Thus, the pronounced prevalence of hypovitaminosis D throughout the globe and its steady progression have turned “ children's vitamin” into one of the main objects of interest for the rapidly aging population of developed countries. Not in vain modern doctors called vitamin D - vitamin sun and longevity.