THE SUN AND THE VITAMIN D Uzm. Dr. Murat Baykır Created: 2016-03-16 12:32:21
View Count: 10520


Today, it been proven in many studies that; sunrays and UV-rays disrupt DNA structure of cells and they suppress the immune system: Therefore they cause many diseases including skin cancers.


But sunrays do not have only harmful effects. Especially the ray called UVB is the most important source of vitamin D. It also has some positive effects including on the sense of sight, destruction of pathogenic microorganisms, human psychology and on some skin diseases.

When it is considered from this perspective, constantly avoidance from the sun or never being exposed to sun is not good.

The main source of vitamin D in our body is a ray called UVB which comes from the sun. Almost 80- 90% of daily intake of vitamin D is obtained from solar radiation. Unfortunately very low amount of vitamin D is obtained nutrients and foods.

For the emergence of a positive effect on health, vitamin D level should remain at a normal level.

Vitamin D enables to have adequate level of calcium and phosphate in blood which are required for bone formation, mineralization, growth and repair in the body. It is involved in the body's defense system. It increases calcium absorption from the small intestine.

There are two forms of vitamin D;

  • Ergocalciferol (vitamin D2)
  • Cholecalciferol (Vitamin D3)

It is transformed to its active form calcitriol – i.e. 1,25 – dihydroxy vitamin - by reaching to liver and kidney.

Although the main source of vitamin D is sunlight; milk, yogurt, bread, cereals, fish, meat, cheese and eggs containing foods also contain vitamin D. While the sun is mainly a D3 source, these foods contain Vitamin D2 and Vitamin D3.

According to some sources, elderly persons, dark-skinned persons and the persons who are exposed to insufficient sunlight should take vitamin D from outside through foods or food supplements.

Vitamin D deficiency leads to deterioration of bone metabolism; therefore they cause rickets in children, osteomalacia and osteoporosis in adults.

UV rays are grouped into 3 groups as follows;

UVA ( > 315- 400nm)

UVA2 (320 - 340nm)

UVA1 ( > 340- 400nm)

UVB ( > 280 - 315nm)

UVC ( > 100 - 280nm)

The main source of ultraviolet rays is the sun.

Almost all of the UVC radiation and 70-90 % of UVB radiation are blocked in the atmosphere during the transition to the Earth. Therefore very small amount of ultraviolet reach the earth. However, even this small amount of UV is enough to have harmful effects.

Among the factors affecting our exposure to UV lights; there are: the country that we live in, the month that we are in, time of the day, whether it is cloudy or not and how high we are from the sea level.

Ultraviolet’s negative effects on increasing skin cancer have been shown in many studies. Of course, after learning this reality, the importance of sun protection measures has emerged.

However, some studies shown that sunrays have positive effects on treatment of certain diseases; therefore they show us that we should not live completely away from the sun. Many studies proved that; UV radiation has positive effects on prostate, breast, colon, ovarian, bladder, esophagus, kidney, lung, pancreas, stomach and uterine cancer; especially it reduces the mortality rates of these cancers. It is considered that; this protective effect has been reached by causing vitamin D synthesis in the body by UVB rays. However, the periods of this study, were the periods that we did not try to be protected from the sun and we were exposed to intense ultraviolet radiation. Now, we know that; in order to ensure adequate vitamin D levels, is not necessary and also it is not recommended the excessive exposure to UV radiation (with the recommendations of the World Health Organization).

Although the required daily sunray exposure duration and time in order to provide adequate serum vitamin D levels depend on the latitudinal characteristics of the region; the average time is 15 minutes in summer and 20 minutes in winter. Dark-skinned persons need nearly double of this time.

In exposure to the sun; face should be protected as much as possible; light-skinned people should be exposed to sun as little as possible; and the people who are exposed to very little sun should also consume foods containing vitamin D –and they should also take supplemental medication, if needed –.


- In order to get vitamin D, do not expose especially children to direct sunlight. Protect much better to children under 2 years of age, if possible, do not expose them to direct sunlight.

- Stay away from the sun, especially between the hours of 10:00 to 16:00. Avoidance from the sun is the best way to be protected from the sun.

- NEVER stay under the sun for tanning purposes.

- Apply proper amount of appropriate sun protector half an hour before sun exposure. If you're in a open field, use sun protector again in every 2 hours.

- Wear a hat.

- Solarium is NEVER recommended.


• The sun is the major cause of facial wrinkles.

• the son that we are exposed during our life is effective in the formation of skin cancer and its effect occurs cumulatively.

• Until we are 18 years old, we are exposed to 70-80% of the total amount of sunrays that we exposed during our whole life. So, we should be protected from the sun starting from our birth.

• Our circumstantial exposure to the sun during the day is 5 times more than the intentional exposure.

• We are not exposed to sun's harmful rays only in summer; we are exposed them in every season. So we should be protected both in winter and in summer!

• According to the WHO, the sun exposure to the upper parts of our hands and to our face during 15 minutes per day is enough to satisfy all our daily need for vitamin D.

• Sunspots are important symptoms which show that you are not adequately protected from the sun. So, be careful!

This post has been written by Uzm. Dr. Murat Baykır and viewed 10520 times.