AbstractThe foetus relies on sufficient nutrient supply from the mother for optimal growth and development in the uterus. Fish is an excellent source of nutrients including proteins, polyunsaturated fatty acids and antioxidants such as selenium; however, fish consumption also increases exposure to the environmental toxin methylmercury (MeHg). Owing to this exposure, the risks and benefits of fish consumption has been of concern for many decades as many communities around the world rely on fish as their main source of animal protein. The overall aim of this thesis was to examine associations between maternal diet, with a focus on fish consumption, and markers of inflammation, oxidative stress and child outcomes. This thesis provides an extensive review of changes in maternal serum cytokine concentrations in healthy pregnancy and in women who developed preeclampsia. The critical review provided, for the first time, a detailed insight into the cytokine profile in normal pregnancy, which is important when investigating the impact of environmental factors on the cytokine profile in a healthy pregnancy cohort. Following from this, associations between infant MeHg exposure, cord cytokines and polyunsaturated fatty acids (PUFA) were undertaken in a high fish eating healthy pregnancy cohort. To explore the impact of habitual dietary patterns on inflammation during pregnancy, associations between maternal dietary patterns and markers of inflammation at 28 weeks gestation were examined. Finally, the relationship between maternal fish consumption and markers of inflammation, oxidative stress and infant birth outcomes was investigated.
The review indicated tumour necrosis factors (TNF)-α increases as pregnancy progresses, interleukin (IL)-8 decreases in the second trimester and IL-4 concentrations remain consistent throughout gestation. Furthermore, alterations in the normal immune response contributes to pregnancy health as preeclampsia as associated with elevated pro-inflammatory cytokines and lower IL-10 in the second trimester may be an early predictor for developing preeclampsia. Subsequent chapters in this thesis focused on the mother-child pairs participating in the Seychelles Child Development Study (SCDS) Nutrition Cohort 2 (NC2), a longitudinal observational study designed to investigate prenatal exposure to methylmercury (MeHg) through fish consumption on child development. The Republic of Seychelles is a high fish eating population and despite relatively high infant prenatal exposure to MeHg, there was no overall association between cord MeHg concentrations and the cord cytokine profile, with or without adjusting for PUFA. Meanwhile, total n-3 PUFA was associated with lower IL-10 and total Th2 cytokines, suggesting n-3 PUFA may have a role in the regulation of the inflammatory milieu in pregnancy. The impact of habitual dietary patterns during pregnancy in NC2 on inflammation was determined using dietary pattern analysis. A “Western” dietary pattern was significantly associated with higher pro-inflammatory markers while the “Traditional Seychellois” dietary pattern was characterised by fish and fruit and may have a beneficial role in immune regulation through associations with chemokines, monocyte chemoattractant protein-1 (MCP-1) and Thymus and Activation-Regulated Chemokine (TARC). Further analysis of the NC2 mothers found maternal fish consumption reported by a fish use questionnaire (FUQ) significantly associated with IL-6, but not with any other marker of inflammation and oxidative stress or infant birth outcomes.
Overall, this thesis highlights the importance of maternal diet in relation to inflammation and oxidative stress in pregnancy. Considering the importance of fish consumption around the world and the nutritional benefits to foetal development, this thesis provides further evidence supporting the safety of maternal fish consumption during pregnancy.
|Date of Award||May 2021|
|Sponsors||Department for the Economy, United States National Institute of Environmental Health Sciences & Government of the Republic of the Seychelles|
|Supervisor||Maria Mulhern (Supervisor), Alison Yeates (Supervisor), Emeir Mc Sorley (Supervisor) & Sean Strain (Supervisor)|
- Fish consumption
- Dietary patterns