The 2-Way Relationship Between Red Wine Polyphenols and Gut Microbiota

“An editorial article in the journal Gastroenterology considers the relationship between red wine polyphenols and gut microbiota.
Recent evidence from observational studies demonstrates a role for red wine in the promotion of beneficial gut microbiota”. A paper from Le Roy et al in the same issue of the journal, reports an association between red wine polyphenols and gut microbiota α-diversity, with only weak associations with white wine and no association with beer, cider, spirits, or all alcohol. The authors propose benefits to gut health even from infrequent red wine consumption and suggest a unique interaction between red wine polyphenols and the modulation of gut microbiota, which poses the question of whether long-term trials are warranted to elucidate potential health-promoting effects of red wine consumption.
The editorial states “The red wine polyphenols include flavonoids (anthocyanins and flavan-3-ols), nonflavonoids (stilbenes), gallic acid, oligomeric and polymeric proanthocyanins, catechins, and phenolic acid, and are proposed to exhibit health- promoting effects through reduction of oxidative stress and promotion of beneficial gut bacteria. Once ingested, relatively small amounts of red wine polyphenols are absorbed in the small intestine (5%–10%), with the remainder reaching the colon as the central location of activity and metabolism by the residential microbiota “producing” polyphenolic conjugates that can enter systemic circulation. However, interindividual differences in the gut microbiota play an important role in bioavailability of polyphenols and their gut microbiota metabolites. The anti-inflammatory activity of red wine polyphenols is well-defined, and its influence on gut microbiota diversity cannot be seen as single-sided, but rather a 2-way relationship. The gut microbiota is relatively stable through adulthood, but can be affected by antibiotic medications and changes in food intake, and is pivotal for the onset and development of various metabolic and inflammatory conditions.
The production of red wine includes the skin of the grapes resulting in nearly a 10-fold higher polyphenolic content than white wine. The consumption of red wine polyphenols is controversially associated with multiple health benefits ranging from reduction in cardiovascular” “disease risk factors, the metabolic syndrome and depression, improved cognition, and health benefits associated with gut microbiota diversity.Red wine polyphenols seem to increase populations of beneficial bacteria while inhibiting potentially pathogenic bacterial populations.A systematic review of clinical trials published between 2006 and 2018 examined the effects of red wine polyphenols and grapes on gut microbiota.Only 1 included study lasting 20 days reported changes in gut microbiota composition and participants consumed either 272 mL/d of red wine or dealcoholized red wine.The findings indicated divergence between groups of several different gut microbiota phyla and species, highlighting complexity surrounding the ethanol content in red wine. The other 6 studies reported increased red wine polyphenols microbial metabolites in feces, urine, plasma, and ileal fluid, representing the modulation of red wine polyphenols by intestinal bacteria and further adding another layer of intricacy to the ‘two-way relationship’.
Evidence of gut microbiota modulation from observational studies is also increasing. Across 3 cohorts, Le Roy et al found improved α-diversity, particularly barnesiella, in discordant twin analyses, which may be associated with improved cholesterol metabolism and body composition. Results from a Danish study of overall wine intake in 720 adolescents with a 20- or 22-year follow- up, reported an association with less weight gain until midlife, but not for beer and spirits.10 Wine consumption was also associated with better overall nutrition and lifestyle, whereas moderate wine drinkers exhibited better overall health and quality of life. Moderate intake of red wine is recommended as part of the Mediterranean dietary pattern and is associated with successful aging,a J-shaped relationship with all-cause mortality,and is often associated with the “French Paradox” referring to lower cardiovascular disease rates despite high saturated fat consumption in this population. However, it is not possible to derive cause and effect owing to confounding variables in epidemiologic studies such as socioenvironmental factors, healthy user bias, and limitations of self- reported dietary collection methods.” “The benefits of red over white wine are often attributed to resveratrol. Consumption of this stilbene may protect against fat accumulation through inhibition of lipogenesis and increase insulin-mediated glucose uptake, potentially lowering circulating blood glucose levels.A review of resveratrol trials indicated that its supplementation is not sufficient for the management of obesity despite anti-inflammatory effects.The levels of “pure” resveratrol used in short-term trials, if compared with those found in red wine, indicate consumption of well over 2 L of wine required to reach the equimolar levels, leading to health problems owing to alcohol levels consumed. In observational studies, beneficial effects of red wine polyphenols are observed at low and moderate regular wine consumption levels, suggesting benefits are only partially owing to resveratrol”.
The authors conclude that “It is without doubt that modifications of the gut microbiota are at the intersection between dietary intake and beneficial health outcomes, and understanding the benefits of red wine polyphenols on gut microbiota remains presented with challenges and controversies. Some of these include the diversity of consumed wines and variation in their polyphenolic content that is influenced by variety of factors. Even with doses that are exceeding physiologically relevant concentrations, evidence of cardiometabolic effects is inconclusive. Therefore, whether moderate to high dosages will exhibit beneficial health effects without negative implications on gut barrier integrity and gut microbiota remains unknown. This might be further elucidated with technological and research advances in the –omics areas, where red wine polyphenols byproducts might be investigated from the population perspective”.
Source: Untangling the 2-Way Relationship Between Red Wine Polyphenols and Gut Microbiota. Naumovski, NenadPanagiotakos, Demosthenes B.D’Cunha, Nathan
M. et al. Gastroenterology, Volume 158, Issue 1, 48 – 51.”