Influence of moderate beer consumption on human gut microbiota and its impact on fasting glucose and β-cell function

Beer is a beverage that has been consumed worldwide for thousands of years due to social, religious, and cultural reasons; it contains polyphenolic compounds as well as phenolic acids with a potential positive effect on human health. This study aimed to explore the impact of moderate beer consumption on human health and gut microbiota diversity. Three hundred fifty-five mL of non-alcoholic beer (NAB) or alcoholic beer (AB) were consumed daily by the participants for 30 days in each study. Anthropometric measures, blood samples for biochemistry, and fecal samples for microbiota analysis were collected on Day 1 and Day 30. Microbial diversity was characterized by high-throughput sequencing of 16S rDNA libraries, and data were analyzed using the QIIME pipeline. We found that NAB and AB have effects on the composition of the gut microbiota, favoring the proliferation of Bacteroidetes with respect to Firmicutes. No increase in weight, waist, and hip parameters was observed, and the liver and lipid profile values were not modified for NAB. In addition, the consumption of NAB induced a decrease in fasting blood serum glucose and an increase in functional β cells, while, on the other hand, there was an increase in blood serum glucose and a decrease in functional β cells with the consumption of AB. In general, beer consumption neither changed anthropometric values, nor affected liver function. Although the glucose values decreased with NAB or increased with AB, they remained within the normal range. Our conclusion is that moderate consumption of NAB has a positive effect on human health via supplementation of biological active polyphenol and phenolic acids, and by enrichment of the gut microbiota diversity with beneficial bacteria, while the presence of alcohol in AB interferes with this effect. More work should be done on this topic before general conclusions are drawn.