According to a recent study, Vitamin D deficiency can be linked to asthma. This makes the populations of sunlight deficient regions more prone to this disease of the respiratory tract.

In the study, published in the American Journal of Respiratory and Critical Care Medicine, Dr. Juan C. Celedon at Boston's Brigham and Women's Hospital and co-investigators examined the association between vitamin D levels and markers of asthma severity and allergy in 616 asthmatic children between the ages of 6 and 14 from Costa Rica. They found that 175 had insufficient levels of vitamin D.

The investigators found that lower levels of vitamin D were associated with more asthma hospitalizations in the previous year, more airway hyperactivity in lung function tests, more use of anti-inflammatory asthma medications like inhaled steroids in the previous year, and higher blood levels of allergy markers.

However the investigators have not yet been able to establish any cause-effect relationship.

Humans primarily acquire vitamin D through their skin which synthesizes it with the help of sunlight. However, some food products can also be a source of this vitamin such as flesh of certain fish, cheese, egg yolk, etc.