Vitamin D, which is absorbed mainly thanks to the sun, is a protective factor against childhood asthma. A new study led by researchers from Valencia shows that children who live in colder, more humid cities, where sunlight hours are more limited, are at greater risk of suffering from this respiratory problem.

The research, carried out on a sample of more than 45,000 children and adolescents of nine Spanish cities and published in International Journal of Biometeorology, highlights that climatic conditions, especially solar radiation, explain in many cases the high geographical variation in the prevalence of asthma in Spain.

"Although more studies are needed on the subject - the hypothesis is only five years old - it is clear that an average exposure to the sun is important for the assimilation of vitamin D, a compound that is becoming increasingly important in the prevention of diseases such as asthma, tuberculosis or other infectious diseases, "explains the epidemiologist at the Center for Public Health of Castellón and lead author of the research, Alberto Arnedo-Pena, in an information on the Synch Platform collected by Europa Press.

Children who live in colder, wetter cities, with fewer hours of sunlight, are more at risk for asthma

In fact, the 90% of vitamin D is synthesized thanks to solar exposure. This vitamin, which is found in different cellular receptors, is usually located at lower levels in people who have asthma. Therefore, the results confirm that in areas where there is less sun and more humidity (northern Spain), the prevalence of the disease in children is higher.

In the Anglo-Saxon countries (where there are fewer hours of sun than in the Mediterranean) there is talk of the convenience of being exposed to the sun for 20 to 30 minutes a day, avoiding the hours of maximum risk (from 12 to 16 hours). At the moment, there are no similar data for Spain.

Once the benefits of the sun king are assumed, the problem arises in countries from 40º north latitude, where during the winter months not enough vitamin D is absorbed. "In these countries supplements should be taken to avoid any risk "advises Arnedo-Pena.

Newborns And Vitamin D: Levels Could Predict Respiratory Risks (November 2019).