The findings, published in the Journal of Allergy and Clinical Immunology, showed repeated bouts of vitamin D deficiency in early childhood were linked to higher rates of asthma at aged 10, as well as allergy and eczema.
The study also found that allergic immune responses were more common in children with low vitamin D in the first few years, while children with vitamin D deficiency at 6 months of age were more likely to experience two conditions previously associated with heightened asthma risk: increased colonisation of the upper airways by harmful bacteria and increased susceptibility to severe lower respiratory infections involving fever.
Lead author Dr Elysia Hollams from the Telethon Kids Institute said the findings shed new light on a contested 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.”
She said the study was the first to track vitamin D levels from birth to asthma onset, and it had shown a clear link between prolonged vitamin D deficiency in early childhood and the development of asthma.