Lifestyle, dietary and environmental exposures in infancy and the development of allergic sensitization

Allergy related diseases have increased in the Western world, affecting nearly half of the children. Lifestyle, dietary and environmental changes are thought to be important for disease risk and disease development. The aim of the prospective ALADDIN (Assessment of Lifestyle and Allergic Disease During INfancy) cohort is to study how lifestyle and environmental factors during pregnancy and early childhood affect the development of allergic disease in children. The aim of this thesis was to study lifestyle, environmental and dietary exposures during pregnancy and infancy in relation to the development of allergic sensitization in the ALADDIN birth cohort. In study I we investigated if there are differences in concentrations of toxic and essential metals in maternal blood, placenta and cord blood between 40 mother-child pairs with and 40 without an anthroposophic lifestyle. Metal concentrations were analyzed using inductively coupled plasma mass spectrometry. We found higher concentrations of Cd, Pb and Co in samples from mother-child pairs with an anthroposophic lifestyle. None of the studied lifestyle factors explained the higher concentrations observed in this study. In study II we investigated if the long chain fatty acid composition in breast milk was associated with allergic sensitization in the child at two years of age. 225 mother-child pairs were included in this study. We found an inverse association between the concentration of omega-3 fatty acids and child sensitization at two years of age. However, this association could not explain the lower prevalence of sensitization among children of anthroposophic families. In study III we investigated if the incidence and prevalence of food, animal and pollen sensitization differed with lifestyle and age of the children. 100 children from anthroposophic, 209 from partly anthroposophic and 165 children from non-anthroposophic families were included. We found a lower incidence of food allergen sensitization among children of anthroposophic families. The lower prevalence of sensitization in children from anthroposophic families was largely explained by the lower incidence of food sensitization before one year of age. In study IV we studied the development specific IgE to egg, milk and peanut from six months to five years of age in 372 children, with a particular interest in low levels of IgE. IgE concentrations were divided into non-sensitized (≤0.09 kU/L), low levels (0.1-0.34 kU/L) and sensitized (≥0.35 kU/L). At six months, 5% of the children had low IgE levels to egg, 14% to milk and 4% to peanut. Low levels to egg seemed to be more transient than low levels to milk. Early low levels to egg and milk seemed to decrease over time, but might increase the probability of sensitization to inhalant allergens. In conclusion, this thesis together with previous publications from the ALADDIN cohort lead to better understanding of risk and protective factors during pregnancy and infancy for the development of allergic disease in children