Vitamin D is a group of fat-soluble chemicals (calciferols). There are two main representatives of this group - ergocalciferol (vitamin D 2 ) and cholecalciferol (vitamin D 3 ). The latter has the maximum biological activity, and therefore is the main representative of this group. Moreover, vitamin D 3 can be formed under the influence of ultraviolet rays or come from animal food into the human body, while ergocalciferol comes only from food. However, vitamins D 2 and D 3 are only provitamins for their conversion in the liver, and then in the kidneys into the active metabolite - calcitriol, which causes all the effects of vitamin D.
Vitamin D and the sun
The amazing property of vitamin D is in its independent formation when exposed to human skin sunlight and artificial ultraviolet radiation. This happens due to the presence of provitamin in the human epidermis, which under the influence of solar radiation turns into vitamin D.
The amount of high-grade vitamin D synthesized from provitamin, among other things, depends on the level of skin pigmentation. It is known that the darker the skin of a person is, the less active the processes of synthesis of vitamin D are. This can be regarded as a protective mechanism that prevents excessive formation of the “solar” vitamin.
However, the fair-skinned men of the northern countries, deprived of sun exposure, as a rule, do not develop a deficient state of vitamin D, since their diet is rich in seafood, in particular fatty fish, which are a rich source of vitamin D.
The possibility of the formation of vitamin D under the influence of sunlight weakens with age. This may be one of the reasons why the development of osteoporosis is increased in older people. Against the background of the fact that elderly people do not receive enough sunlight (they spend a lot of time at home), as well as an unbalanced diet, a vitamin D-deficient state may develop in the autumn-winter period.
The value in the body and the daily need
The main properties of vitamin D are in collaboration with calcium in building bone tissue, improving the absorption of calcium and phosphorus in the intestine and embedding them in bone tissue. As a result, the concentration of calcium in the blood increases, and it copes with its functions more effectively.
In some conditions associated with the pathology of bone tissue, such as bone fragility, fractures, osteo-articular tuberculosis, osteoporosis, it is possible to use higher doses of vitamin D.
Vitamin D and Testosterone
According to information from Dr. S. Kaadri’s book Testosterone Factor, testosterone is involved in building bone tissue, helps absorb calcium, and embed this element in the parts of the body that it needs.
If calcium intake is not enough, testosterone molecules are sent to the bones, participating in their recovery. This leads to the fact that a smaller amount of testosterone performs its direct function in the body.
Consumption of a sufficient amount of calcium along with vitamin D relieve testosterone from the work of “maintaining” bone, without interfering with it to show its hormonal action elsewhere.
Although vitamin D has an extensive effect on testosterone, the main ones are:
- Collaboration with calcium in building bones (improved calcium absorption from the intestines and bone mineralization);
- The transformation of estrogen (female hormone) into its less active forms.
Consequences of vitamin D deficiency for men:
- Reducing the effectiveness of testosterone, with all the ensuing consequences.
Sources of Vitamin D
In ideal conditions, solar exposure is enough to replenish the daily need for vitamin D. It also matters how the sun's rays are exposed to human skin. For example, exposure to solar radiation through glass does not activate the production of cholecalciferol. The same applies to clothes - on sunny days, you should try to open the sun rays as many skin areas as possible (change pants for shorts, shirts for sleeveless T-shirts, etc.). The use of sunblock also prevents the formation of vitamin.
Residents of northern countries do not suffer from vitamin D deficiency, because their diet is rich in fatty fish varieties - one of the main food sources of vitamin D. Such fish contain essential omega-3 and omega-6 fatty acids and enough fat for adequate absorption of vitamin D 3
Vitamin D is not destroyed during cooking. For the normal assimilation of this vitamin, adequate intake of proteins, vitamins A, C, vitamins of group B, calcium, phosphorus, essential fatty acids is necessary. A lot of this combines fatty fish.
The content of vitamin D in food:
(estimated availability of 100 g)
Even at the dawn of the discovery of vitamin D, it was shown that irradiation of products with ultraviolet significantly increases the amount of "solar" vitamin in them. This practice is still popular in the USA, for example, when irradiating milk and other fatty foods.
By the principle of the American food industry, milk, rich in vitamin D, can be obtained at home by irradiating it with an ultraviolet lamp. With this treatment, 1 liter of milk accounts for the daily need for this vitamin. But only one glass of such milk can be drunk per day!
- V. G. Liflyansky "Vitamins and Minerals", 2010;
- T.P. Emelyanova "Vitamins and Mineral Substances: Complete Encyclopedia", 2000;
- T. S. Morozkina, A. G. Moyseyenok “Vitamins”, 2002;
- Edaplus.info - a source of illustrations to the article.