Results of a small study indicated that red wine polyphenols were associated with increases in levels of certain gut bacteria, including Bifidobacterium, Enterococcus, Prevotella, and Bacteroides.
In addition, researchers from the University of Barcelona report that blood pressure fell, as did total and HDL cholesterol levels, while levels of C-reactive protein (CRP), a well-established marker of inflammation, “decreased significantly”.
“We found that red wine polyphenols can inhibit non-beneficial bacteria from the human microbiota and potentiate the growth of probiotic bacteria such as bifidobacteria, which could be implicated in the reduction of CRP and cholesterol observed in our study, promoting health benefits in the host,” wrote the scientists in the American Journal of Clinical Nutrition.
“Although further research is required, the results of this study suggest the possible prebiotic benefits associated with the inclusion of red wine polyphenols in the diet.”
Prebiotics are defined as: "Non-digestible substances that provide a beneficial physiological effect on the host by selectively stimulating the favorable growth or activity of a limited number of indigenous bacteria".
The Spanish researchers recruited 10 healthy male volunteers to participate in their randomized, crossover, controlled intervention study. The participants went through four phases for the study: The first was a washout period during which they avoided any alcohol or red wine for 15 days. The participants were each required to drink only de-alcoholized red wine (272 mL/d), red wine (272 mL/d), or gin (100 mL/d) for 20 days each.
Fecal samples showed that all the intervention periods produced changes in the populations of certain gut microbes, with the changes different for the different beverages consumed.
“These results indicate that changes in the gut microbiota composition of healthy subjects occur after a dietary intervention, which disagrees with previous studies regarding the subject specificity of the predominant fecal communities and their stability over time and resistance to perturbations,” said the researchers.
While gin only produced an increase in Bacteroides and Clostridium, and a disappearance of Prevotellaceae, compared with the other interventions, both red wine groups produced the greatest increase in the diversity of the fecal microbiota.
Indeed, both red wine groups displayed significant increases in Firmicutes and Bacteroidetes, but no changes in Lactobacillus species.
In addition, the red wine groups were associated with increases in Bifidobacteria, which was correlated to decreases total cholesterol and HDL cholesterol, and CRP concentrations.
“CRP is a blood marker of inflammation, and its concentration is a specific predictor of cardiovascular event risk in healthy subjects. Its reduction in our study links polyphenol intake to cardiovascular benefits in the host,” wrote the researchers.
“This was the first in vivo study to show that regular moderate consumption of red wine could have a noteworthy effect on the growth of select gut microbiota,” they concluded.
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.111.027847
“Influence of red wine polyphenols and ethanol on the gut microbiota ecology and biochemical biomarkers”
Authors: M.I. Queipo-Ortuno, M. Boto-Ordonez, M. Murri, et al.