Reference
Queipe-Ortuño M. Influence of red wine polyphenols and ethanol on the gut microbiota ecology and biochemical biomarkers. Am J Clin Nutr. 2012;95:1323-1334.
Design
Randomized, crossover, controlled intervention study
Participants
Ten healthy male volunteers, 45–50 years of age, without the presence of risk factors for metabolic syndrome or infectious or inflammatory disease
Study Parameters
Following an initial 15-day washout period in which subjects consumed no alcohol, participants were assigned to consume either red wine (272 mL/d), de-alcoholized red wine (272 mL/d), or gin (100 mL/d), for a period of 20 days. Dose was portioned for equivalence in ethanol content for red wine and gin, and comparable total phenols in red wine and de-alcoholized red wine. Treatments were crossed over consecutively with no washout period in between. At baseline and at the end of each 20-day period, fecal, blood, and urine samples were collected for analysis of compliance, fecal microbiota, and comparison of serum biomarkers.
Key Findings
In urinalysis, both resveratrol and dihydroresveratrol concentrations were increased following red wine and de-alcoholized red wine interventions, confirming not only the presence of resveratrol polyphenol in these 2 groups but also the metabolization of resveratrol by microflora. Initial fecal DNA profiling identified 5 main phyla of fecal bacteria in all subjects; Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, and Fusobacteria. Throughout the study, the genera ratio within these specific phyla changed as compared to baseline. The highest change in diversity in fecal microbiota was noted after red wine intake only—specifically an increase in proteobacteria, firmicutes, and bacteroidetes phyla. Red wine increased enterococcus, bacteroides, and prevotella and decreased clostridium genera. The consumption of red wine polyphenols in both de-alcoholized red wine and red wine was associated with an increase of Blautia coccoides-Eubacteria rectale, bifidobacterium, eggerthella lenta, and bacteroides uniformis.
In addition, consumption of red wine decreased both systolic and diastolic blood pressure, while de-alcoholized red wine significantly decreased systolic blood pressure only. Both red wine and de-alcoholized red wine groups demonstrated a significant reduction in glutamate-oxaloacetate transaminase, γ-gluatmyl transpeptidse, triglycerides, HDL cholesterol, and C-reactive protein (CRP).
Clinical Implications
The health benefits of red wine have been researched extensively over the last 10 years, although little has been reported on its effects on the gut microbiota.1 The overall reduction of clostridium genera in this study could show a protective effect by red wine (resveratrol) in the human gut, thus reducing susceptibility to a range of conditions.2–5 In addition to decreasing pathogenic bacteria, resveratrol intake also showed a prebiotic effect in concentrations of beneficial gut bacteria. Commonly supplemented, Bifidobacteria has been shown to be preventive in a broad spectrum of gastrointestinal conditions and has been implicated in immune regulation and pathogen resistance.6–8
The current study adds to the growing body of research that dietary polyphenols may exert some of their positive effects through interaction with the gut microbiota such as through prebiotic effects and the production of bioactive metabolites.
The intake of red wine polyphenols also showed beneficial effects on blood pressure, triglyceride levels, cholesterol, and CRP. Of these parameters, decreased cholesterol and CRP were associated with increased bifidobacteria concentrations. The absence of cardiovascular benefits with gin consumption suggests these effects were associated with polyphenols, not ethanol, although ethanol may affect the gut microflora.9 The reduction of CRP is of particular significance as CRP has been proposed as a marker of general inflammation and a possible predictor for long-term cardiometabolic risk.10–12
The current study adds to the growing body of research that dietary polyphenols may exert some of their positive effects through interaction with the gut microbiota such as through prebiotic effects and the production of bioactive metabolites. Though further research is needed with a larger population, longer duration, and a washout period between crossovers, this study has provided a foundation to further examine the effects of various polyphenols on the gut microbiota and their overall relationship to human health and the prevention and management of disease.
