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

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 thefirst 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

Proportions of polyunsaturated fatty acids in umbilical cord blood at birth are related to atopic eczema development in the first year of life

Atopic eczema, the most common atopic disease in infants, may pave the way for sensitization and allergy later in childhood. Fatty acids have immune-regulating properties and may regulate skin permeability. Here we examine whether the proportions of fatty acids among the infant and maternal plasma phospholipids at birth were associated with maternal dietary intake during pregnancy and development of atopic eczema during the first year of age in the Nutritional impact on Immunological maturation during Childhood in relation to the Environment (NICE) birth cohort. Dietary data were collected with a semi-quantitative food frequency questionnaire, fatty acids were measured with GC-MS and atopic eczema was diagnosed by a pediatric allergologist at 12 months of age. We found that higher proportions of n-6 PUFAs (including arachidonic acid) but lower proportions of n-3 PUFAs (including DPA) in the infant’s phospholipids at birth were associated with an increased risk of atopic eczema at 12 months of age. The n-6 and n-3 PUFAs were related to maternal intake of meat and fish, respectively. Our results suggest that prenatal exposure to unsaturated fatty acids is associated with eczema development in the infant. Maternal diet during pregnancy may partly explain the fatty acid profiles in utero

Biomarkers of seafood intake during pregnancy – Pollutants versus fatty acids and micronutrients

Intake of fish and seafood during pregnancy may have certain beneficial effects on fetal development, but measurement of intake using questionnaires is unreliable. Here, we assessed several candidate biomarkers of seafood intake, including long-chain omega 3 fatty acids (n-3 LCPUFA), selenium, iodine, methylmercury, and different arsenic compounds, in 549 pregnant women (gestational week 29) in the prospective birth cohort NICE (Nutritional impact on Immunological maturation during Childhood in relation to the Environment). Proportions of the fatty acids eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) in erythrocytes were measured using gas chromatography with flame ionization detector. Selenium was measured in blood plasma and erythrocytes, mercury and arsenic in erythrocytes, and iodine and several arsenic compounds in urine, using inductively coupled plasma mass spectrometry, arsenic compounds after first being separated by ion exchange high-performance liquid chromatography (HPLC). Each biomarker was related to intake of total seafood and to intake of fatty and lean fish, and shellfish in third trimester, estimated from a semi-quantitative food frequency questionnaire filled out in gestational week 34. The pregnant women reported a median total seafood intake of 184 g/week (5th-95th percentiles: 34–465 g/week). This intake correlated most strongly with erythrocyte mercury concentrations (rho = 0.49, p < 0.001), consisting essentially of methylmercury, followed by total arsenic in erythrocytes (rho = 0.34, p < 0.001), and arsenobetaine in urine (rho = 0.33, p < 0.001), the main form of urinary arsenic. These biomarkers correlated well with intake of both fatty fish, lean fish, and shellfish. Erythrocyte DHA and plasma selenium correlated, although weakly, mainly with fatty fish (rho = 0.25 and 0.22, respectively, both p < 0.001). In conclusion, elevated concentrations of erythrocyte mercury and urinary arsenobetaine can be useful indicators of seafood intake, more so than the n-3 LCPUFAs. However, the relative importance of the biomarkers may differ depending on the type and amount of seafood consumed

Association of maternal urinary fluoride concentrations during pregnancy with size at birth and the potential mediation effect by maternal thyroid hormones: The Swedish NICE birth cohort

Background: Observational studies have indicated that elevated maternal fluoride exposure during pregnancy may impair child neurodevelopment but a potential impact on birth outcomes is understudied. Objectives: To evaluate the impact of gestational fluoride exposure on birth outcomes (birth size and gestational age at birth) and to assess the potential mediating role of maternal thyroid hormones. Methods: We studied 583 mother-child dyads in the NICE cohort in northern Sweden. Maternal fluoride exposure was assessed by measuring urinary concentrations at late pregnancy (median: 29th gestational week) using an ion selective electrode. Plasma levels of free and total thyroxine (fT4, tT4) and triiodothyronine (fT3, tT3), and thyroid stimulating hormone (TSH) were measured with electrochemiluminescence immunoassays. The infant\u27s weight, length, head circumference, and gestational age at birth were extracted from hospital records. Results: Median urinary fluoride concentration was 0.71 mg/L (5th-95th percentile 0.31–1.9 mg/L; specific gravity adjusted). In multivariable-adjusted regression models, every 1 mg/L increase of maternal urinary fluoride was associated with a mean increase in birth weight by 84 g (95%CI: 30, 138), length by 0.41 cm (95%CI: 0.18, 0.65), head circumference by 0.3 cm (95%CI: 0.1, 0.4), and with increased odds of being born large for gestational age (OR = 1.39, 95%CI: 1.03, 1.89). Every 1 mg/L increase of maternal urinary fluoride was also associated with a mean increase of the plasma fT3:fT4 ratio (B = 0.007, 95%CI: 0.000, 0.014), but not with the hormones or TSH. In mediation analyses, the maternal fT3:fT4 ratio did not explain the urinary fluoride-birth size relationships. Discussion: Gestational urinary fluoride concentrations were associated with increased size at birth and even with increased odds of being born large for gestational age. The fluoride-related associations with increased size at birth were not explained by changes in maternal thyroid hormone levels