Achieving health promoting gut microbiome modulation through sustainable, nutritious and healthy foods.

The global pandemic of diet-related non-communicable diseases and the fact that global food production represents one of the largest contributors to greenhouse gas emissions, have identified unhealthy and unsustainably food chains as a major societal health challenge and a risk to ecosystem stability. This thesis aimed to investigate if digestion of nutritious, less highly processed foods could lead to health-promoting changes in the gut microbiota. Our modern Western-style diet (MWD) is characterized by high intake of extremely processed foods, which contain significant concentrations of inflammatory advanced glycation end-products (AGE) implicated in metabolic disease development. Novel observations in this thesis showed that chronic exposure to dietary AGE modulated gut microbiota (GM) community structure rendering it more similar to the GM previously observed in diabetic/obese mice. Further, I demonstrated that elevated systemic inflammatory markers could be mediated by AGE induced changes in GM composition. Measuring the potential of whole plant foods to improve gut health, a local broccoli ecotype (Broccolo of Torbole, BR) and Moringa oleifera were investigated using in vitro models of the human GM and intestinal epithelium. BR significantly reduced bacterial richness and evenness, increased Escherichia-Shigella relative abundance and decreased Alistipes and Ruminococcus 1. The GM extensively metabolized BR polyphenols and increased concentrations of short chain fatty acids. However, BR did not impact on intestinal permeability, using a Caco-2 monolayer model and trans-epithelial electrical resistance (TEER). This thesis provided novel insights on the fate of Moringa glucosinolates and polyphenols during faecal fermentation and on their potential beneficial activity on gut health, with glucomoringin significantly increasing TEER. Microbial communities are also involved in healthy and sustainable food production. Characterizing the successional development of local organic sauerkraut production, this thesis established a culture collection of sauerkraut lactic acid bacteria of potential future biotechnological evaluation and measured metabolite production during sauerkraut fermentation. Sauerkraut water improved immune response of a Caco-2-peripheral blood mononuclear cell (PBMC) in vitro model of the gut associated immune system upon inflammatory LPS challenge. Finally, since sustainable diets rely on sustainable and nutritious foods, I analyzed the role of the GM in improving the sustainability of farmed trout. Novel sustainable feeds containing poultry by-products (P) or insect protein (Hermetia illucens (H) meal), were investigated for their potential impact on fish growth performance, GM composition and inflammatory biomarkers. P increased the relative abundance of protein-degraders Paeniclostridium and Bacteroidales, while H increased chitin-degraders Actinomyces and Bacillus. This study also provided evidence of feed-chain microbiome transmission of Actinomyces from insect H feed to trout GM. The analysis of gut microbiomes therefore represents an innovative strategy to define healthy reference diets, to characterize the potential health effects of local and traditionally produced foods, to identify new sustainable and nutritious crops, and to drive the urgently needed transformation of the global food system. In order to obtain more sustainable, healthy and nutritious food production systems a better understanding and management of microbiomes along the food chain has never been more important.