Vitamin D levels may affect asthma

Scores of studies in the last few years hint that adequate vitamin D levels may be much more important to human health than previously thought. Many of the studies also suggest that most people don't get enough vitamin D, which is synthesized in the body in response to sunlight and is also found in some foods, such as fish and fortified milk. The latest salvo in the vitamin D debate is a study published today showing that the nutrient may be linked to asthma severity.

Researchers from Harvard looked at 616 children with asthma in Costa Rica, in a part of the country with high rates of asthma. They found children with lower vitamin D levels were much more likely to have been hospitalized for asthma in the previous year, had more airway hyperactivity and were more likely to use inhaled corticosteroids. The children also had more evidence of allergies.

The study, published in the May 1 issue of the American Journal of Respiratory and Critical Care Medicine, is the first to demonstrate an association between circulating levels of vitamin D and markers of asthma severity and allergy, the researchers said.

"This study suggests that there may be added health benefits to vitamin D supplementation," a co-author of the study, Dr. Juan Celedon, said in a news release.

The researchers said that giving vitamin D supplements to asthma patients who are deficient may help with their asthma control.

"Whether vitamin D supplementation can prevent the development of asthma in very young children is a separate question, which will be answered by clinical trials that are getting underway," Celedon said.

The study took place in a country with abundant sunshine, noted doctors from the University of Aberdeen, Aberdeen, Scotland, in an editorial accompanying the study. The use of sunscreen and efforts to avoid too much sun exposure may be contributing to lower vitamin D levels in people in many parts of the world. And, they say, it's hard to get enough vitamin D from food alone.

-- Shari Roan

Photo credit: Lawrence K. Ho / Los Angeles Times