Vitamin D may protect against pollution-associated asthma symptoms in obese children

A new study finds vitamin D may be protective among asthmatic obese children living in urban environments with high indoor air pollution.

Many factors contribute to worsening asthma symptoms, such as blood levels of vitamin D, obesity, and high indoor air pollution. Photo: NIEHS

“Asthma is an immune-mediated disease,” said Sonali Bose, M.D., lead author of the study and assistant professor of medicine, pulmonary, critical care, and sleep medicine at the Icahn School of Medicine at Mount Sinai, and adjunct faculty at Johns Hopkins. “From previous scientific studies, we knew that vitamin D was a molecule that may influence asthma by impacting antioxidant or immune-related pathways.”

Bose explained that at the time the study was being conceived, researchers were seeing vitamin D deficiencies across the U.S. “It became very clear that African-Americans were at higher risk for vitamin D deficiency, particularly black children,” she said. “We were also noticing a heavy burden of asthma in inner city minority children. It seemed as though vitamin D deficiency and asthma were coincident and interacting in some way.”

The study tested three factors – air pollution levels in homes, blood vitamin D levels, and asthma symptoms in 120 school-aged children with preexisting asthma. One-third of the study participants were also obese.

Overall, they found that having low blood vitamin D levels was related to the harmful respiratory effects of indoor air pollution among obese children with asthma. Conversely, in homes that had the highest indoor air pollution, higher blood vitamin D levels were linked to fewer asthma symptoms in obese children.

“What surprised us the most was that the findings of the study showed the effects were most pronounced among obese children,” Bose said. “This highlights a third factor at play here – the obesity epidemic – and helps bring that risk to light when considering individual susceptibility to asthma.”

One way to increase blood vitamin D levels is to increase sun exposure, but that isn’t always possible in urban environments, or in people with darker skin pigmentation.

Another way is through dietary supplements or eating more foods that are high in vitamin D, such as fatty fish, mushrooms, or foods fortified with vitamin D, such as bread, orange juice, or milk. (National Institutes of Health)

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