Evaluation of the Effects of a Short Supplementation With Tannins on the Gut Microbiota of Healthy Subjects

Abstract

Western diet, high in fats and sugars and low in greens, contributes to dysbiosis of the gut microbiota, which can lead to a variety of chronic diseases related with inflammation. Supplementation with bioactive compounds can help to maintain a healthy eubiotic state. Thus, we performed a 4-weeks nutritional intervention on healthy volunteers to investigate whether a blend of natural tannin extracts could induce healthy changes in the microbial intestinal ecosystem. Changes in the composition and functionality of the microbiota could be observed from the first two weeks onward. 16S rRNA amplicon next-generation sequencing (NGS) revealed a significant increase in microbial diversity at the end of the intervention, as well as trends toward increases in the relative abundances of several beneficial taxa, such as Ruminococcus bicirculans, Faecalibacterium prausnitzii, Lachnospiraceae UCG 010, Lachnospiraceae NK4A136, Bacteroides thetaiotaomicron and B. uniformis. Remarkably, some of the identified taxa were also identified as responsible for an increase in the production of short-chain fatty acids (SCFAs), microbial metabolites that contribute to the modulation of the immune system and have various other anti-inflammatory functions in the gut. Taken together, these results suggest that the tannin supplementation could exert a prebiotic effect by selectively stimulating the growth and the activity of bacteria that are advantageous for the host.

Randomized placebo-controlled trial of oral tannin supplementation on COVID-19 symptoms, gut dysbiosis and cytokine response

“…The relatively short tannin intervention could represent one explanation why we did not observe significant shifts in α-diversity nor β-diversity, or in tannin-induced compositional shifts which we have previously been reported for Bacteroidaceae, Lachnospiraceae and Ruminococcaceae families ( Molino et al, 2022 ; Molino, Lerma-aguilera, et al, 2021). Members of these families are recognized for being producers of short chain fatty acids (SCFAs), interesting metabolites with a powerful effect in counteracting the inflammatory state ( Akhtar et al, 2022 ).…”

“…A major limitation of our study is related to the short tannin intervention time (14 days) restricted to the hospitalization of COVID-19 patients. In a previous study we showed that supplementation with a tannin blend led to an increase in SCFA release after the two weeks, whereas significant changes in microbiota composition emerged only after 4 weeks of treatment ( Molino et al, 2022 ). This might explain why in our study we could begin to observe a reduction in cytokines after 14 days of tannin supplementation, but shifts in microbiota composition were not readily evident.…”

“…Several reports have highlighted the influence of different diets on COVID-19 severity, which merits deeper investigation of therapeutic options based on nutritional support favoring restoration of gut microbiota function ( Kalantar-Zadeh et al, 2020 , Liang, 2020 ). Tannins are natural bioactive compounds that positively impact gut microbiota function, in part by promoting expansion of probiotic bacteria (Molino, Lerma-aguilera, et al, 2021; Molino et al, 2022 ). These polyphenol substrates are actively metabolized by gut microbes with end products, such as short chain fatty acids, urolithins and quercetin that can regulate local and systemic immune responses ( Fanos et al, 2020 , Molino et al, 2018 ).…”

Garcinia dulcis Flower Extract Alters Gut Microbiota and Fecal Metabolomic Profiles of 2K1C Hypertensive Rats

“…The genus Erysipelotrichaceae _UCG_003 of family Erysipelatoclostridiaceae has been linked with the formation of isobutyrate, isovalerate and valerate [ 29 ]. Lachnospiraceae are known for including many species able to produce SCFAs, which have often been revealed to have a positive association with health [ 30 ]. The Lachnospiraceae NK4A136 group has been positively correlated with the production of both acetic acid [ 30 ] and butyric acid [ 31 , 32 ].…”

“…Lachnospiraceae are known for including many species able to produce SCFAs, which have often been revealed to have a positive association with health [ 30 ]. The Lachnospiraceae NK4A136 group has been positively correlated with the production of both acetic acid [ 30 ] and butyric acid [ 31 , 32 ]. Dorea has been reported to produce acetate and lactate, which may serve as substrates for butyrate production [ 33 ].…”