BACKGROUND: Few studies have investigated the effect of dietary polyphenols on the complex human gut microbiota, and they focused mainly on single polyphenol molecules and select bacterial populations.
OBJECTIVE: The objective was to evaluate the effect of a moderate intake of red wine polyphenols on select gut microbial groups implicated in host health benefits.
DESIGN: Ten healthy male volunteers underwent a randomized, crossover, controlled intervention study. After a washout period, all of the subjects received red wine, the equivalent amount of de-alcoholized red wine, or gin for 20 d each. Total fecal DNA was submitted to polymerase chain reaction(PCR)-denaturing gradient gel electrophoresis and real-time quantitative PCR to monitor and quantify changes in fecal microbiota. Several biochemical markers were measured.
RESULTS: The dominant bacterial composition did not remain constant over the different intake periods. Compared with baseline, the daily consumption of red wine polyphenol for 4 wk significantly increased the number of Enterococcus, Prevotella, Bacteroides, Bifidobacterium, Bacteroides uniformis, Eggerthella lenta, and Blautia coccoides-Eubacterium rectale groups (P < 0.05). In parallel, systolic and diastolic blood pressures and triglyceride, total cholesterol, HDL cholesterol, and C-reactive protein concentrations decreased significantly (P < 0.05). Moreover, changes in cholesterol and C-reactive protein concentrations were linked to changes in the bifidobacteria number.
CONCLUSION: This study showed that red wine consumption can significantly modulate the growth of select gut microbiota in humans, which suggests possible prebiotic benefits associated with the inclusion of red wine polyphenols in the diet. This trial was registered at controlled-trials.com as ISRCTN88720134
Health benefits of moderate wine consumption have been studied during the past decades, first in observational studies and more recently, in experimental settings and randomized controlled studies. Suggested biological pathways include antioxidant, lipid regulating, and anti-inflammatory effects. Both the alcoholic and polyphenolic components of wine are believed to contribute to these beneficial effects.
Although several of these studies demonstrated protective associations between moderate drinking and cardiovascular disease, atherosclerosis, hypertension, certain types of cancer, type 2 diabetes, neurological disorders, and the metabolic syndrome, no conclusive recommendations exist regarding moderate wine consumption. Yet, it is suggested that the physician and patient should discuss alcohol use. In the CASCADE (CArdiovaSCulAr Diabetes & Ethanol) trial, 224 abstainers with type 2 diabetes were randomized to consume red wine, white wine or mineral water for two years.
Here, we summarize our previous findings, offer new evidence concerning the differential effects of wine consumption among men and women, and further suggest that initiating moderate alcohol consumption among well-controlled persons with type 2 diabetes is apparently safe, in regard to changes in heart rate variability and carotid plaque formation