Allergic diseases (asthma, eczema, hay fever and food allergy) are major health issues in Australia with more than 20% of the population now affected by allergies. The incidence of food allergy in particular has increased dramatically over the past 10-20 years, with the greatest burden of this new epidemic being in young children. Recently low blood levels of vitamin D have been found to be a risk factor for the development of eczema and food allergies in Australian infants. Over the past two decades in particular, changes to lifestyle resulting in more indoor activities along with increased sun safe practises have resulted in less UV light exposure, which is the major source of vitamin D in humans. Infant oral vitamin D supplementation is routine in many Northern Hemisphere countries, but due to the belief that Australian children are exposed the adequate sunlight it has not been routine here.
Research question: This study is the first study globally to prospectively investigate the influence of infant oral vitamin D supplementation and UV light exposure on vitamin D status, immune function development and allergic disease outcomes.
Methodology: This study is a double-blind, randomised placebo controlled trial whereby infants with an increased risk of developing allergies (due to a family history) are orally supplemented with 400 IU vitamin D/day, or placebo, from birth to 6 months of age. Uniquely in this study a UV dosimeter is also worn by the infants from birth to 6 months of age to measure infant actual UV light exposure. Blood samples are collected at 3, 6 and 12 months of age to determine relationships between oral vitamin D intake and UV light exposure with blood 25(OH)D (vitamin D) concentration, immune cell function responses to allergens and on the development of allergic conditions in infancy such as eczema and food allergy.
Autism project, Vitamin D and glucocorticoid interactions in early life: implications for adult neuropsychiatry? - Caitlin Wyrwoll, Andrew Whitehouse
Epidemiological studies and animal models have highlighted a link between early life vitamin D deficiency to subsequent alterations in neurodevelopment and adult neuropsychiatric disorders. Recent research by our group in rodent models has revealed a novel and potentially crucial role of the hypothalamic-pituitary-adrenal (HPA) axis in vitamin D deficiency. The HPA axis produces glucocorticoids, which are classically referred to as 'stress' hormones, but these hormones have an additional critical role in the maturation of fetal and neonatal tissues. The developing brain is particularly sensitive to glucocorticoids and over-exposure has negative ramifications for brain development and subsequent adult behaviours. Our data demonstrate that vitamin D deficiency in rodent pregnancy results in increased exposure of the foetal brain to glucocorticoids, and alterations in fetal neural gene expression and adult behaviours indicative of autism spectrum disorder-like behaviour. Unravelling the significance of vitamin D and glucocorticoid interactions will be crucial for the proper understanding of how vitamin D deficiency impacts on neurodevelopment and later health.