Gut microbiota in host metabolism and cancer: From biological pathways to novel treatment strategies

There is compelling evidence that the gut microbiota are key regulators of many physiological processes, including eating behavior, mental well-being, immune response and metabolism. Although this influence seems a promising target for novel therapeutics, the underlying mechanisms through which these microbiota exert their influence are far from apprehended. In this thesis, we aimed to further elucidate the microbial influence in the regulation of body composition, insulin sensitivity (IS) and anti-tumor efficacy. Based on the research questions stated in the thesis, we conclude the following: 1. Modulation of the gut microbiota through FMT can – partially – affect body composition and effectiveness of anticancer therapies. 2. New microbial-metabolite pathways involved in insulin resistance and anticancer efficacy, could not be identified, emphasizing the intricate relation between microbes, metabolites and host health. 3. Visiting in-laws during Christmas disturbs the gut microbiota composition and might consequently affect both physical and mental health. These findings provide important insights in the role of the gut microbiota in host metabolism, cancer therapy and mental wellbeing. However, many more questions remain to be answered before we can move towards microbiota-based therapies to treat metabolic diseases and enhance anti-tumor efficacy and toxicity.