Abstract
A diet high in polyphenols is associated with a diversified gut microbiome. Tea is the second most consumed beverage in the world, after water. The health benefits of tea might be attributed to the presence of polyphenol compounds such as flavonoids (e.g., catechins and epicatechins), theaflavins, and tannins. Although many studies have been conducted on tea, little is known of its effects on the trillions of gut microbiota. Hence, this review aimed to systematically study the effect of tea polyphenols on the stimulation or suppression of gut microbiota in humans and animals. It was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Articles were retrieved from PubMed and Scopus databases, and data were extracted from 6 human trials and 15 animal studies. Overall, large variations were observed in terms of microbiota composition between humans and animals. A more consistent pattern of diversified microbiota was observed in animal studies. Tea alleviated the gut microbiota imbalance caused by high-fat diet-induced obesity, diabetes, and ultraviolet-induced damage. The overall changes in microbiota composition measured by beta diversity analysis showed that tea had shifted the microbiota from the pattern seen in animals that received tea-free intervention. In humans, a prebiotic-like effect was observed toward the gut microbiota, but these results appeared in lower-quality studies. The beta diversity in human microbiota remains intact despite tea intervention; supplementation with different teas affects different types of bacterial taxa in the gut. These studies suggest that tea polyphenols may have a prebiotic effect in disease-induced animals and in a limited number of human interventions. Further intervention is needed to identify the mechanisms of action underlying the effects of tea on gut microbiota.
Highlights
Studies on the relationship between gut microbiota and health have garnered much interest in recent years
The following key terms were applied during the search: (Tea) AND (Gut Microbiota OR Gut Microbiome OR Gut Microflora): 1
This review showed that Camellia sinensis could modulate the gut microbiota
Summary
Studies on the relationship between gut microbiota and health have garnered much interest in recent years. The term “gut microbiota” is defined as the microbial ecosystem or community that resides within the human intestinal tract [1]. The gut ecosystem comprises microorganisms, mainly bacteria, and a small number of viruses, protozoa, and eukaryotic organisms such as fungi that are distributed throughout the gastrointestinal tract [2]. Gut microbiota play an important role in human health, and they are considered a “forgotten organ” and “super-organism” that maintains intestinal epithelium integrity [4,5,6]. The dominant groups of bacteria phyla in the gut are Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria [5,9]
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