Table 1.
Main preclinical and human data reporting the effects of polyphenols on gut microbiota and associated mechanisms.
| Polyphenol/Source | Condition/Model | Impact on Microbiota and Associated Mechanisms | Ref. |
|---|---|---|---|
| Preclinical data | |||
| Epicatechin gallate | In vitro assay in bacterial medium | Sensitizes methicillin-resistant S. aureus to beta-lactam antibiotics | [74] |
| Green tea and red wine polyphenols | In vitro assay in bacterial medium | Inhibits the VacA toxin, a key virulence factor of Helicobacter pylori | [75] |
| Quercetin | High fat diet (animal model) | Reduction of BW. Decrease Firmicutes populations, Erysipelotrichi class and Bacillus genus. Down-regulation of Erysipelotrichaceae, Bacillus and Eubacterium cylindroides | [76] |
| Proanthocyanidin rich red wine extract | Colon cancer (animal model) | Treated rats exhibited considerably lower levels of Clostridium spp. and higher levels of Bacteroides, Lactobacillus and Bifidobacterium spp. | [77] |
| Coffee and Caffeic acid | Colon cancer (animal model) | Intake precisely inhibited colon cancer metastasis and neoplastic cell transformation in mice by inhibiting TOPK (T-LAK cell-originated protein kinase) and MEK1 | [78] |
| Resveratrol | Colonic cancer (animal model) | Reduced activities of faecal and host colonic mucosal enzymes, such as α-glucoronidase, nitroreductase, β-galactosidase, mucinase, and α-glucosidase | [79] |
| Resveratrol | DSS induced colitis (animal model) | Stimulated faecal cell counts of Lactobacillus and Bifidobacterium spp. | [80] |
| Polyphenols (from plants) | In vitro assay in bacterial medium | Control of food-borne pathogenic bacteria without inhibitory effect on lactic acid bacteria growth | [81] |
| Polyphenols (from algae) | In vivo assay in TD2M mice | Hypoglycemic effect together with decreased counts of Turcibacter and Akkermansia and increase of Alistipes | [82] |
| Polyphenols (Chinese propolis, Brasilian propolis) | DSS induced colitis (animal model) | Modulation of the GM composition, namely reduction of the Bacteroides spp. | [83] |
| Polyphenols (Prunella vulgaris honey) | DSS induced colitis (animal model) | Modulation of GM composition, with increased Bacteroidetes/Firmicutes ratio and restoration of Lactobacillus spp. populations | [84] |
| Polyphenols (from fungi) | DSS induced colitis (animal model) | Modulation of GM composition, with reduction of Firmicutes/Bacteroidetes ratio and restoration of Lactobacillus spp. populations | [85] |
| Human studies | |||
| (+)Catechin and (−)Epicatechin | In vitro assay with faecal samples of healthy volunteers | Inhibition of Clostridium histolyticum growth and boosted the growth of members of the Clostridium coccoides-Eubacterium rectale group and E. coli, while growth of Lactobacillus Spp. and Bifidobacterium Spp. remained comparatively unaltered | [86] |
| Proanthocyanidin rich grape extract | Fecal flora and odor (healthy adults | Significantly increase in the number of Bifidobacteria | [87] |
| Cocoa-derived flavanols | Healthy humans | Stimulate growth and proliferation of Bifidobacterium spp. and Lactobacillus spp., together with reduction in plasma C-reactive protein (CRP) | [71] |
| Polyphenols (Red wine) | Human study | Regular intake results in BP reduction, lipid profile improvement (e.g., TGs) and decline in uric acid levels, together with increase in the proliferation of Bacteroides spp. | [88] |
| Polyphenols (Green tea, fruits, vinegar wine) | Obese volunteers | Weight lowering effect together with alteration in gut microflora | [89] |
| Dihydroxylated phenolic acid | In vitro LPS-induced inflammation | Exhibits potent anti-inflammatory properties, lowering the secretion of TNF-α, IL-1b and IL-6 in LPS-induced peripheral blood mononuclear cells from healthy individuals | [90] |
| Polyphenols (from spices) | Healthy humans | Glucose uptake and appetite modulation | [91] |