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An estimated 300 million people worldwide suffer from asthma, a chronic disease marked by recurrent attacks of breathlessness and wheezing as the lining of the lungs’ bronchial tubes swells and narrows the airways.

A new study suggests that a vitamin D deficiency – a common problem — increases the likelihood of flare-ups in people whose condition cannot be sufficiently controlled with medication. Rather than adding more pharmaceuticals, such people may want to have their vitamin D levels checked and add supplementation if necessary.

A team led by Dr. Ronit Confino-Cohen of the Allergy and Clinical Immunology Unit at Meir Medical Center in Kfar Saba came to this conclusion after analyzing the medical records of nearly four million members of Clalit Health Services, Israel’s largest healthcare provider.

They zeroed in on records of 307,900 patients age 22 to 50 whose vitamin D levels were documented between 2008 and 2012. Of those, some 21,000 also were diagnosed with asthma.

Looking at the 21,000 records, they discovered that those with a vitamin D deficiency were 25 percent more likely than other asthmatics to have had at least one flare-up in the recent past, according to results recently published in the journal Allergy by Confino-Cohen and her colleague Arnon Goldberg, with Becca Feldman and Ilan Brufman of the Clalit Research Institute.

Confino-Cohen, who is on the faculty of Tel Aviv University’s Sackler medical school, says that most of the existing data regarding vitamin D and asthma came from pediatric studies and was inconsistent.

“Our present study is unique because the study population of young adults is very large and ‘uncontaminated’ by other diseases,” she explains.

The researchers found that vitamin D-deficient asthmatics were at a higher risk of an asthma attack if their condition was uncontrolled – defined as being prescribed at least five rescue inhalers, one prescription of oral corticosteroids or visiting the doctor for asthma at least four times in a single year.

A walk in the sunshine

“The real conclusion is that if a young adult with asthma is not responding to regular medication, he or she should probably get vitamin D levels checked,” the physician tells ISRAEL21c. “Adding vitamin supplementation is certainly less harmful than adding medication.”

While sufficient vitamin D can be obtained from 10 minutes of sun exposure daily, concerns about skin cancer cause many doctors to recommend getting the vitamin instead from supplements or from foods such as eggs, fatty fish, mushrooms or fortified drinks.

Confino-Cohen said that she anticipates further research will support her team’s findings “and open a new treatment modality to the population of uncontrolled asthmatics.”

Worldwide, the incidence of asthma is steadily rising. According to the US Centers for Disease Control and Prevention, about one in 12 people in the United States has asthma, or about 25 million people. From 2001 to 2011, the number of Americans with asthma grew by 28 percent.

“We know a lot about this disease and many therapeutic options are available. So it’s quite frustrating that the prevalence of asthma is not decreasing and many patients suffer exacerbations and significant impairment in their quality of life,” Confino-Cohen says. “Increasing vitamin D levels is something we can easily do to improve patients’ quality of life.”

She emphasizes that her team’s conclusions are an educated guess at this point.

“We know that vitamin D has an effect on the immune system and is considered protective against asthma, but there is not much data on the genetic connection,” she says.

“You would have to follow vitamin D levels of newborns till adulthood before making an assumption on the connection. We have speculated based on information we know from the lab and immunological effects we know in terms of osteoporosis and cancer. It’s not that we know for sure, but it makes sense.”