A vitamin of D3 is a calciferol 2936290000
Vitamins of group D are formed under the action of ultraviolet radiation in tissues of animals and plants from sterols.
Vitamins of group D include:
- vitamin D 2 - ergocalciferol; isolated from yeast, its provitamin is ergosterol;
- vitamin D 3 - cholecalciferol; isolated from animal tissues, its provitamin is 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 two vitamins are called vitamin D - D 2 and D 3 - ergocalciferol and cholecalciferol are crystals without color and odor, resistant to exposure to high temperatures. These vitamins are fat-soluble, i.e. are soluble in fats and organic compounds and insoluble in water.
The activity of vitamin D preparations is expressed in international units (ME): 1 ME contains 0.000025 mg (0, td style = "vertical-align: top"> synthesis in the body
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Vitamin D is formed in the skin under the influence of sunlight from provitamins ... Provitamins, in turn, age (aging skin loses its ability to synthesize vitamin D);
Additional food sources of vitamin D are dairy products, fish oil, egg yolk. However, in practice, milk and dairy products do not always contain vitamin D or contain only trace (insignificant) amounts (for example, 100 g of cow's milk contains only 0.05 mg of vitamin D), so their consumption, unfortunately, cannot guarantee that our need for this vitamin will be covered. In addition, milk contains a large amount of phosphorus, which interferes with the absorption of vitamin D.
The main function of vitamin D is to ensure normal growth and development of bones, prevent rickets and osteoporosis. It regulates mineral metabolism and promotes the deposition of calcium in bone tissue and dentin, thus preventing osteomalacia (softening) of bones.
Entering the body, vitamin D is absorbed in the proximal region small intestine, and always in the presence of bile. Some of it is absorbed in the middle sections of the small intestine, an insignificant part is in the iliac. After absorption, calciferol is found in the composition of chylomicrons in free form and only partially in the form of ether. Bioavailability is 60-90%.
Vitamin D affects the general metabolism during the metabolism of Ca2 + and phosphate (HPO2-4). First of all, it stimulates the absorption of calcium, phosphates and magnesium from the intestine. An important effect of the vitamin in this process is to increase the permeability of the intestinal epithelium for Ca2 + and R.
Vitamin D is unique - it is the only vitamin that acts as a vitamin and as a hormone. As a vitamin, it maintains the level of inorganic P and Ca in blood plasma above the threshold value and increases Ca absorption in the small intestine.
Symptoms of hypovitaminosis< (ergocalciferol) is prescribed to pregnant women to prevent rickets in children at 30-32 weeks of pregnancy in divided doses for 10 days, for a total of 400,000-600,000 ME; breastfeeding mothers - 500 IU daily from the first days of feeding until the start of the drug use in a child.
In order to prevent rickets, children are given ergocalciferol with three weeks of age, the total dose for the course is 300000 ME.
For the treatment of rickets, appoint 2000-5000 ME daily for 30-45 days.
When treating with large doses of vitamin D preparations, it is recommended to simultaneously prescribe vitamin A, In this case, calcium can penetrate into the walls of blood vessels and provoke the formation of atherosclerotic plaques. This process can be accelerated if there is a deficiency in the body of magnesium.
Vitamin D preparations are contraindicated in such diseases as:
- hypercalcemia ,
- pulmonary tuberculosis (active forms),
- peptic ulcer of the stomach and duodenum,
- acute and chronic diseases of the liver and kidneys, ;
- organic heart disease.
|Composition||A vitamin of D3 is a calciferol|