Diet and dietary biomarkers during pregnancy and lactation in relation to offspring allergy development

Sammanfattning: Allergy causes a large burden on society and reduces the quality of life for the individual. The increased allergy incidence over the last decades cannot be explained by genetics. Research has indicated that diet, which is a modifiable factor, might influence the risk of developing allergy. Traditional dietary assessment methods are, however, prone to large measurement errors. Objective biomarkers may be complementary but have typically not been applied in cohorts with pregnant women and in the early life context. The objective of this thesis was to investigate if the diet during pregnancy and lactation is related to offspring allergy development (i.e., atopic eczema, food allergy, and asthma) diagnosed by an allergologist at twelve months of age. The thesis is based on data from the birth cohort Nutritional impact on Immunological maturation during Childhood in relation to the Environment (NICE). Dietary data were collected using a repeated web-based semi-quantitative food frequency questionnaire sent out in gestational week 34, one month postpartum, and four months postpartum. Dietary intakes were quantified based on pictures of portion sizes and reported intake frequency. Maternal and infant blood, urine, and breast milk samples were collected, and nutrients, trace elements, and metabolomics-based food intake biomarkers were related to the self-reported food intake and to allergy diagnosis. The results show that maternal intake of cow’s milk products and saturated fat during lactation was associated with a lower incidence of offspring allergy. Higher proportions of n-6 polyunsaturated fatty acids in umbilical cord plasma phospholipids correlated to a higher incidence of atopic eczema during the first year of life. In addition, food intake during pregnancy was associated with maternal characteristics, primarily age and educational level. Food intake biomarkers known from a general (i.e., non-pregnant or lactating) population seemed useful also during lactation, whilst dietary biomarkers during pregnancy warrant further investigation. In summary, the findings indicate that the most crucial period of time in terms of allergy prevention may be the first months postpartum, rather than during pregnancy. Hence, changing maternal diet during lactation may be a useful strategy for allergy prevention in the offspring.