Vitamin D may shield obese children against pollution-related asthma, study finds

12 Mar 2019 --- Vitamin D may help prevent asthma symptoms in obese children living in high air pollution environments. This is according to a new study from John Hopkins University School of Medicine, published in The Journal of Allergy and Clinical Immunology: In Practice.

The research was funded by the US National Institute of Environmental Health Sciences (NIEHS), part of the US National Institutes of Health (NIH). 

“The research team has identified many factors that make children susceptible to health problems from air pollution throughout Baltimore’s (Maryland, US) inner city,” says Kimberly Gray, Ph.D., Administrator for the Children’s Environmental Health Research Centers program at NIEHS.

One in 12 US children suffers from asthma, which translates into roughly 6 million children, according to the Centers for Disease Control and Prevention. Moreover, the research notes, asthma disproportionately affects urban minorities, such as African-American children. Adding to external pollution, high indoor pollution, such as cigarette smoke, cooking, burning candles and incense are all linked to respiratory issues. This results in exacerbating asthma symptoms and increased hospital visits.

“Asthma is an immune-mediated disease,” says Sonali Bose, M.D., lead author of the study and Assistant Professor of 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.”

The study came at a time when researchers across the US were noting nationwide vitamin D deficiencies, Bose says. 

“It became very clear that African-Americans were at higher risk of vitamin D deficiency, particularly black children,” she says. “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 researchers followed 120 school-aged children from the Baltimore area, with pre-existing asthma symptoms. One-third of the children were obese. They examined three factors, air pollution levels in homes, asthma symptoms and blood vitamin levels. The children were evaluated at the beginning of the study and three times over the following nine months.

The results showed that having low blood vitamin D related to the adverse respiratory effects of indoor air pollution among obese children with asthma. However, in homes that had the highest indoor air pollution, higher 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 notes. “This highlights a third factor at play here – the obesity epidemic – and helps bring that risk to light when considering individual susceptibility to asthma.”

Bose says the next step is identifying ways of increasing vitamin D levels in these children, so they can be more resilient to environmental influences.

“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,” she says. “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.”

“Another important take-home point is how the complex environment comes together to contribute to extra burden of asthma in these low-income, urban communities,” adds senior author Dr. Nadia Hansel, Director of the Division of Pulmonary and Critical Care Medicine at Johns Hopkins. “Our results suggest that improving the asthma burden in the community may require a multi-faceted approach.”

Vitamin D deficiency has been linked to several health issues in children and adults. In October 2018, a University of Leeds study suggested that Europe-wide policy focus could improve intakes of iron, vitamin D, and total folate while also reducing sodium and free sugar intake. 

“A focus on iron and vitamin D intake would be especially beneficial for girls and children over the age of 10,” said Janet Cade, Professor of Nutritional Epidemiology and Public Health at Leeds and co-author.

Moreover, according to research presented at the 57th Annual European Society for Pediatric Endocrinology Meeting in October 2018, simple vitamin D supplementation may be part of an effective strategy to tackle childhood obesity and reduce the risk of serious health problems, such as heart disease, in adulthood.

According to studies, vitamin D supplementation benefits for include reduced risk of heart disease, diabetes and lung attacks in patients suffering from chronic pulmonary disease (COPD).