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Given the relationship between metabolic syndrome (MS) and disturbances of the gastrointestinal (GI) microbiome, the development of strategies to treat MS via modulation of the GI microbiome has gained much momentum. In the first research study of this thesis, we test whether a synbiotic preparation containing Bifidobacteria adolescentis IVS-1 and galactooligosaccharide (GOS) can counteract the development of MS induced by high fat (HF) diet feeding in mice. It was observed that GOS by itself ameliorated hyperglycemia, hyperinsulinemia and index of insulin resistance (IR). However, these benefits were nullified in the synbiotic. Moreover, GOS increased fecal Akkermansia muciniphila and Bacteroides vulgatus levels, which were both positively associated with the observed metabolic benefits. Together, these findings indicate that synbiotic approaches may lead to antagonistic interactions, featured by GOS competition. In the second research study of this thesis, the probiotics Bifidobacteria adolescentis IVS-1 and Bifidobacteria infantis Y2 were compared for their ability to influence metabolic and intestinal parameters in a mouse model of HF diet induced MS. This work showed that neither putative probiotics affected MS or GI parameters. However, both probiotics were able to increase plasma leptin levels. Together, these findings suggest that some probiotics might elicit similar effects on the host despite differences in the criteria used to select them. In conclusion this thesis demonstrated that combinations of prebiotics and probiotics are not always beneficial as treatment with the individual components. Moreover, a given selection method of probiotics does not ensure effectiveness in treating a disease condition.
Advisor: Amanda Ramer-Tait