Vitamin D: what is it and why its deficiency is dangerous?

With the development of the laboratory diagnostic sector, it became possible to determine the level of a variety of active substances in biological material. Thanks to it, we obtain precious information for both individual human health and health of country/region population. Thus, many people learned about the deficiency of vitamin D. According to epidemiological data, on average 80% of the adult and child population of the Russian Federation suffer from insufficient vitamin D.

  1. Why do we need vitamin D?

Vitamin D performs a variety of functions that contribute to the maintenance of physical health of a person.

First, it promotes calcium absorption in the intestine and maintains the necessary levels of calcium and phosphates in the blood to ensure bone mineralization, preventing development of rickets in children and adults.

In simple words, the additional intake of vitamin D with its diagnosed deficiency can significantly reduce the number of falls and fractures dangerous for the elderly.

Secondly, vitamin D is an important link in maintaining the immune system and prevents the development of autoimmune diseases (type 1 diabetes mellitus, multiple sclerosis, rheumatoid arthritis, inflammatory bowel diseases). In addition, vitamin D reduces the risk of developing certain infectious diseases (ARVI, tuberculosis, etc.)

Third, there is evidence that vitamin D deficiency is associated with the risk of polycystic ovarian syndrome (SPS) and reduced quantitative and qualitative characteristics seminal fluid. However, more research is needed to detail the mechanisms of vitamin D’s effects on the reproductive system.

In addition, it is known that the risk of vitamin D deficiency increases when pregnancy occurs. Clinical studies demonstrate a decrease in the incidence of pregnancy complications in patients receiving high doses of vitamin D. Women receiving vitamin D have a reduced risk of vitamin D deficiency (rickets) in a child.

  1. Why is vitamin D lacking?

Before talking about why vitamin D may not be enough, it is necessary to understand what are the stages of this substance “life cycle” in the segment “synthesis /intake – activation”. These stages are presented in Figure 1.




Figure 1 Vitamin D Life Cycle at the “Synthesis-Activation segment”

As can be seen in Figure 1, vitamin D can be synthesized in the body under the influence of sunlight. However, the geographical position of most of the Russian Federation in northern latitude above 35 parallel leads to the fact that the skin produces virtually no vitamin D between November and March.

If we talk about the second way – the intake of vitamin D with food, the main sources of vitamin are some types of fish (salmon, herring, catfish) + fish oil, butter, milk, sour cream, egg yolk, cheese, beef liver. In this case, vitamin D deficiency may be associated with unbalanced nutrition/impoverishment of food, impaired absorption, increased need, impossibility of proper use of vitamin D (for example, in case of obesity, vitamin D is deposited in subcutaneous fatty tissue and is not available to the central blood flow).

Other causes of vitamin D deficiency are impaired digestion and absorption of fats (vitamin D is fat-soluble), as well as loss of vitamin D in urine in combination with the protein binding it at nephrotic syndrome.

  1. What to do?

According to the Clinical Recommendations of the Russian Association of Endocrinologists, people aged 18-50 years are recommended to receive at least 600—800 IU of vitamin D per day for the prevention of vitamin D deficiency, and persons over 50 years of at least 800—1000 IU while the recommended drugs for prevention are colecalciferol (D3) and ergocalciferol (D 2). However, before taking them it is necessary to consult a specialist.

In addition, it is necessary to adhere to a balanced diet and include additional sources of vitamin D in the diet and more often be outdoors especially in sunny weather. It is also useful to include systematic moderate physical activity in preventive measures that contribute to the release of vitamin D from subcutaneous fat.


  1. Berezov T.T., Korovkin B.F. Biological chemistry. – M.: Medicine, 2002.
  2. Petrushkina A.A., Pigarova E.A., Rozhinskaya L.Y. The prevalence of vitamin D deficiency in Russian Federation. Osteoporosis and Bone Diseases. 2018;21(3):15-20. (In Russ.)
  3. Pigarova E.A., Rozhinskaya L.Y., Belaya J.E., Dzeranova L.K., Karonova T.L., Ilyin A.V., Melnichenko G.A., Dedov I.I. Russian Association of Endocrinologists recommendations for diagnosis, treatment and prevention of vitamin D deficiency in adults. Problems of Endocrinology. 2016;62(4):60-84. (In Russ.)