Repeated periods of vitamin D deficiency in the first decade of life in high-risk children are associated with increased risk of asthma, eczema, and allergic sensitization that persists to age 10 years, new research shows.
The study led by researchers from the Telethon Kids Institute in Western Australia found the inverse relationship between 25(OH)D concentration and concurrent sensitization was most pronounced during infancy.
One mechanism by which vitamin D deficiency can drive asthma development is by promoting early allergic sensitization, a known proasthmatic factor in high-risk children, they said in the study published in the Journal of Allergy and Clinical Immunology.
They noted that their findings mirrored their earlier findings in a larger Australian community cohort linking vitamin D deficiency at age 6 years with subsequent sensitization and wheeze at age 14 years.
Lead author Dr Elysia Hollams said the findings shed new light on a controversial area of research.
“We know vitamin D plays an important role in regulating the immune system and promoting healthy lung development,” said Dr Hollams.
“But while it has been suggested that inadequate vitamin D may be a factor contributing to the surge in asthma rates over recent decades, previous studies investigating the relationship have yielded conflicting results. There has been a lack of research looking at whether vitamin D deficiency is more detrimental at certain periods in childhood.”
“Our study is the first to track vitamin D levels from birth to asthma onset, and it has shown a clear link between prolonged vitamin D deficiency in early childhood and the development of asthma”
“We’ve also shown for the first time that babies deficient in vitamin D have higher levels of potentially harmful bacteria in their upper airways, and are more susceptible to severe respiratory infections.”
“Earlier research by our team and others around the world has identified the first two years of childhood as a critical period during which allergies and chest infections can combine to drive asthma development in susceptible children. Our new findings identify vitamin D deficiency as a co-factor that may promote this process.”
Watch: The authors give a summary of their research findings.
But Dr Hollams said there were still many unknowns in the field of vitamin D research and cautioned against vitamin D supplements.
“We still don’t know what the optimal level of vitamin D is for good lung health and immune function, and we don’t know if supplementation would address this issue, or if healthy sun exposure is what is required, given that vitamin D is an indirect measure of recent sun exposure.”
According to Professor Katie Allen from the Murdoch Childrens Research Institute the findings raises the question of whether there should be increased Vitamin D exposure through the diet.
“Australia is one of the few developed countries that does not fortify its food supply with Vitamin D and therefore it may not be a coincidence that we have the highest rates of allergic disease including food allergies in the developed world,” she said.
“We believe that Vitamin D supplementation trials in infancy are essential to answer this important public health question.”