Vitamin D is unique due to the fact that our body synthesizes it.
Exposure of the skin to the sun, i.e. to its UVB radiation, creates Vitamin D3, which travels through the lymphatic system, veins, and from the veins to the liver. In the liver, it is converted into an active form, which is further metabolized in the kidneys and gives 1.25 (OH)2D as the ultimate active form of vitamin D in our body.
Vitamin D formed in this way participates in more than 200 gene expressions, as well as in the metabolism of calcium and phosphorus. The importance of vitamin D in our body is reflected in the fact that almost all organs have vitamin D receptors.
It is believed that 50% of the world’s populationis deficient in vitamin D. The reason lies in changed life habits, i.e. spending most of the day indoors, as well as in air pollution.
In the winter, light-skinned people need 15 to 30 minutes of sun exposure at midday, primarily of the face, hands and shoulders. People with skin type III need 30 minutes to an hour, and people with skin types IV and V need 2 hours in the sun. During this period, 1,000 IU of vitamin D3 is produced daily. In summer, 6 minutes is sufficient for skin types I and II, and 15 minutes for skin type III.
Most citizens of Serbia have skin type III.
Exposing the whole body to the sun until a minimum amount of redness appears on the skin, produces between 10,000 IU and up to 25,000 IU of vitamin D3. Vitamin D3 produced in this way lasts twice as long compared to the vitamin ingested through food or supplements.
Applying SPF 30 to the skin reduces the vitamin D synthesis by 95%. Liver or kidney diseases directly lead to vitamin D deficiency.
The same applies to systemic diseases that consume large amounts of vitamin D such as sarcoidosis, tuberculosis, fungal infections, disorders od lipid metabolism, diabetes, hypothyroidism, obesity.
The role of vitamin D
Vitamin D acts as a steroid hormone in our body. Its action is necessary for the metabolism of bones, intestines, muscles, brain, heart. The life cycle and destruction of cells is dependent on vitamin D. It passes through the blood-brain barrier. The entire brain tissue has vitamin D receptors, although its function in the brain is still unknown.
It has been proven that the possibility of developing colon cancer is reduced by 50% in people with high levels of vitamin D. It is similar with breast cancer.
Cardiovascular diseases are 60% lower in people with adequate vitamin D level.
Obesity in middle age leads to the development of cancer and cardiovascular diseases, and one of the causes is increased consumption of vitamin D.
Depressive states are significantly reduced by adding 20,000 IU to 40,000 IU of vitamin D per week.
Daily supplementation of vitamin D reduces the possibility of bone fractures in later years by 20%.
A Japanese study conducted on children showed that daily supplementation with 1,200 IU of vitamin D reduces the possibility of getting Influenza A (flu) by 40%.
Vitamin D and Covid-19
Vitamin D3 supplementation is used in the prevention of Covid-19 infection. It is believed that the exact effect of this hormone on the survival and severity of the clinical picture of Covid-19 infection will be known in one year. The groups most at risk of getting the Covid-19 virus are the elderly, obese and diabetics. As many as 95% of these individuals are deficient in vitamin D. The protective effect for them should be achieved by taking 4,000 IU per day, while for the general population the amount should be 1,000 IU.
Apart from the fact that vitamin D receptors are located on the cells that participate in immune response, the role of this vitamin is not fully known. It is known that the inflammatory process in the lungs is more massive and more severe in people who are vitamin D deficient.
Vitamin D: Supplements and prevention
Prevention is carried out by vitamin D2 or D3 supplementation.
For newborns and babies up to 12 months of age, the recommended amount is 2,000 IU for 6 weeks in order to achieve a level higher than 30ng/mL.
For children and adolescents between the ages of 1 and 18, the recommended amount is 2,000 IU per day or 50,000 IU per week until an adequate value is reached. The value is maintained by supplementing 400 IU per day.
For adults aged 18 to 50, the recommended amount is 50,000 IU per week for 8 weeks until a value greater than 30 ng/mL is reached. The value is maintained by supplementing 1,000 IU per day.
People with increased need for vitamin D should take 6,000 to 10,000 units a day, and when an adequate level in the blood is achieved, it is maintained with 3,000 -6,000 IU per day.
The importance of vitamin D for the body is great. Numerous studies are still researching its full function in maintaining health. Since a large percentage of the population is deficient in vitamin D, it is necessary to pay attention to supplementation and adequate intake through food.