Simulated gastrointestinal digestion of beer using the simgi® model. Investigation of colonic phenolic metabolism and impact on human gut microbiota

Beer is a source of bioactive compounds, mainly polyphenols, which can reach the large intestine and interact with colonic microbiota. However, the effects of beer consumption in the gastrointestinal function have scarcely been studied. This paper reports, for the first time, the in vitro digestion of beer and its impact on intestinal microbiota metabolism. Three commercial beers of different styles were subjected to gastrointestinal digestion using the simgi (R) model, and the digested fluids were further fermented in triplicate with faecal microbiota from a healthy volunteer. The effect of digested beer on human gut microbiota was evaluated in terms of microbial metabolism (short-chain fatty acids (SCFAs) and ammonium ion), microbial diversity and bacterial populations (plate counting and 16S rRNA gene sequencing). Monitoring beer polyphenols through the different digestion phases showed their extensive metabolism, mainly at the colonic stage. In addition, a higher abundance of taxa related to gut health, especially Bacteroides, Bifidobacterium, Mitsuokella and Succinilasticum at the genus level, and the Ruminococcaceae and Prevotellaceae families were found in the presence of beers. Regarding microbial metabolism, beer feeding significantly increased microbial SCFA production (mainly butyric acid) and decreased ammonium content. Overall, these results evidence the positive actions of moderate beer consumption on the metabolic activity of colonic microbiota, suggesting that the raw materials and brewing methods used may affect the beer gut effects.