Abstract:
Background: Recent studies have reported significant beneficial effects of probiotics for prevention of Gestational Diabetes Mellitus (GDM). However, few studies have evaluated such effects in the context of background diet, specifically dietary fibre. Additionally, to date no studies have assessed the metabolome response to Lactobacillus rhamnosus HN001 supplementation in relation to GDM status and dietary fibre intakes. Therefore, this thesis will assess the dietary intake and metabolite profiles of women who participated in the Probiotics in Pregnancy (PiP) study. Aims: To evaluate, 1) whether the dietary macronutrient intake and, 2) metabolite profiles of PiP study participants differed by probiotic HN001 exposure, dietary fibre intake during pregnancy and GDM development. Methods: Participants were randomised at 14-16 weeks’ gestation to receive HN001 (6x109 CFU) or placebo supplementation daily. Three-day food diaries and blood plasma samples were collected from participants at 26-28 weeks’ gestation. The macronutrient content of the diets was determined using Foodworks 9. Metabolomics analysis was conducted by gas chromatography-mass spectrometry. Results: Protein, fat, and carbohydrate (as % total energy) of the total PiP cohort were within the recommended guidelines for pregnancy. The dietary fibre intake of women diagnosed with GDM was significantly lower compared to women without GDM (p = 0.027). While statistically insignificant, the mean dietary fibre intake was lowest for women who were supplemented with HN001, yet still developed GDM (22.5±8.5g/d, p = 0.637) compared to all other groups. The GDM metabolome was associated with biomarkers of branch chain amino acid catabolism, the tricarboxylic cycle and inflammation. The HN001 metabolome was associated with biomarkers of tryptophan metabolism. High dietary fibre intake (≥25g/d) was associated with histidine, an anti-inflammatory biomarker. Discussion: The success of probiotic supplementation in preventing GDM may depend on sufficient dietary fibre intake. Analysis of the metabolome of PiP study participants indicates that probiotic HN001 supplementation and high dietary fibre intake may prevent GDM by generation of antiinflammatory metabolites including histidine and signalling of tryptophan metabolism.
