The role of the human microbiome in health and disease is under massive investigation by scientists world-wide, especially the gut microbiome. There are great individual differences in the composition of the gut microbiome, which is defined as the number of different types of bacteria present and the relative quantities of each type. Certain difference in composition have been associated with a number of diseases, such as inflammatory bowel disease (IBD), celiac disease, and food allergies. One general measure of gut microbiome health is the diversity of bacterial species present, known as alpha-diversity. Greater diversity is a sign of a healthy microbial community, while reduced diversity is often seen in disease states.
A recent report in the journal Gastroenterology examined the relationship between alcohol consumption and alpha-diversity in three different study groups: one British, one Flemish, and one American. This study looked at the correlation of beer, cider, spirits, red wine, and white wine consumption on alpha-diversity. Red wine drinking was found to be associated with significantly greater alpha diversity, with white wine showing a much lesser association. Consumption of the other alcohols had no correlation with alpha-diversity. This red wine association was seen in all three study groups as well as in a smaller set of matched twins where the twins had different alcohol consumption patterns. In addition to greater alpha-diversity, red wine consumption was associated with higher levels of bacteria in the genus Barnesiella. Barnesiella is normally a minor group of gut bacteria whose role in health is not well defined yet. Fortunately, even infrequent drinking of red wine (once or twice a month) was still associated with better alpha-diversity.
In addition to better gut microbiome diversity, red wine consumption is also correlated with reduced body mass index (BMI) and higher levels of HDL, the “good” cholesterol. The authors speculate that all these positive effects could be due to the high content of polyphenols, such as resveratrol, in red wine compared to other alcohols. Resveratrol is an anti-oxidant with known anti-pathogen and anti-cancer properties, and is often touted as the compound in red grapes that is responsible for many of the reported health benefits of red wines. Interestingly, a study from several years ago showed that Barnesiella has a positive effect in controlling harmful intestinal bacteria, so a red wine-associated increase in Barnesiella could prove helpful in maintaining gut health. It’s important to remember though that this red wine report was one limited study. Consequently, all these correlations and speculations should be taken as very tentative and are just another small step towards understanding the gut microbiome and its important role in our health.