6 factors that influence vitamin D levels in summer


The summer It is an ideal time of year to increase the levels of vitamin D, especially since one of its main sources of obtaining is the ultraviolet rays of the Sun. For this reason, this micronutrient is popularly known as the ‘sunshine vitamin’.

The experts in the field, such as the doctor Michael F. Holick, ensures that 80% of the vitamin D that we have in the body comes from the sun; while only 20% comes from food or vitamin supplements.

Although, despite having these two sources of obtaining it, vitamin D deficiency among the Spanish population is very high. The latest studies carried out during the Covid-19 pandemic speak of a deficit of more than 50%. Something that can also be extrapolated to many countries in Europe.

Factors influencing vitamin D levels

Knowing all the factors that influence vitamin D values ​​is highly complicated. However, regarding its obtaining by the sun’s ultraviolet rays, it is true that there are certain aspects that affect its metabolization.

vitamin D summer sun
Person taking a supplement

The absorption / production process of vitamin D is complex inside the body. It all starts by exposing the skin to the ultraviolet rays of the sun. Later, vital organs such as the liver or kidneys are involved in the production of this vitamin.

Thus, below we explain some of the factors that participate in obtaining this micronutrient from the sun’s ultraviolet rays.

Place of residence

In the farthest places to the Equator from the earth, the sun’s rays do not reach the same way during winter, thus influencing people’s vitamin D levels. The use of warm clothing that covers practically the entire body hinders the incidence of ultraviolet rays.


Sunscreen is essential to avoid sunburn caused by ultraviolet rays. In addition, the different studies carried out in this regard ensure that the use of sunscreen does not reduce the effect of the sun to increase vitamin D levels.

Air quality

Another important aspect that can influence vitamin D levels during the summer is air quality. Carbon particles from burning fuels and wood absorb the sun’s ultraviolet rays and reduce the production of this micronutrient.


As a general rule, obesity is related to low levels of vitamin D and is that being overweight could influence the bioavailability of this micronutrient.

Skin color

People with darker skin need a greater exposure to ultraviolet rays from the sun, compared to people with fair skin that generate the same amount of vitamin D. This is due to the substance known as melanin.


Another factor that can influence is age, since older people have lower levels of the substance in the skin that, through the action of UVB rays, becomes the precursor of vitamin D.

Also, some studies show that older people produce less vitamin D than younger people.

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