Insights & Discussion
Pu-erh tea's fermentation process alters its microbial community, with aging significantly impacting raw but not ripened Pu-erh, and toxic metabolites present support brewing customs.
The researchers looked into the microbial communities inherent in Pu-erh tea, a special blend originating from Yunnan, China. The fresh leaves of the tea plant, Camellia sinensis, undergo two types of fermentation- the traditional raw fermentation and the faster, ripened variant. Using high-throughput rDNA-amplicon sequencing, a method to identify and quantify various bacteria and fungi present, they examined both the leaves and both types of Pu-erh tea. The study also explored possible mycotoxins in the tea profiles through quantitative liquid chromatography-tandem mass spectrometry, a technique used to detect and quantify various substances.
Despite observing significant alterations in the fungal and bacterial compositions due to both fermentation processes, the researchers found the aging process to produce noteworthy changes in raw Pu-erh but not in the ripened type. They identified 390 fungal operational taxonomic units (OTUs) and 629 bacterial OTUs in the leaves and teas. Interestingly, despite the difference in the speed and nature of the fermentation processes, ripened and well-aged raw Pu-erh teas exhibited similar microbial communities alien from those observed in young, raw Ph-erh tea. They also found 25 toxic metabolites, primarily of fungal origin, with the most common being patulin and asperglaucide. These facts lend credibility to the Chinese custom of discarding the first preparation of the Pu-erh tea and using the damp tea for subsequent brewing.
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Pu-erh tea possesses therapeutic mechanisms potentially beneficial for metabolic diseases due to its interaction with liver and gut microbiome.
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The methodology of this research involved reviewing and summarising the processing elements and bioactive components of pu-erh tea. Extensive study of relative human and animal trials was conducted, and the potential therapeutic mechanisms of this tea were examined and extrapolated.
In discussing the results, it was discovered that pu-erh tea evidently has beneficial effects on metabolic diseases, such as hypocholesterolemic and hypolipidemic effects. The research points to the conclusion that the tea's interaction with the liver and gut microbiome is the major contributing factor to these health benefits. It helps regulate tea biotransformation and endogenous metabolism, underlining the tea's potential use in therapeutic interventions.
Pu-erh tea, through the increase of Cinnabarinic acid, can improve obesity induced by circadian rhythm disorders by enhancing fat metabolism and altering gut microbes.
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In this study, a CRD-induced obesity model in mice was developed and Pu-erh tea was used as an intervention. The effect of Pu-erh tea on obesity was observed and determined to come from its production of Cinnabarinic acid (CA). CA was found to promote adipose tissue lipolysis and heat generation response, increasing the sensitivity of fat cells to hormones and neurotransmitters. This was accomplished by targeting the expression of specific receptor proteins in adipose tissue. These processes improved mitochondrial activity in the fat cells and expedited metabolic processes in the adipose tissue, thereby speeding up glucose and fat metabolism.
In the final stage of the study, CA was found to make changes in the gut microbiota and short-chain fatty acids which further helped to improve the lipid accumulation mediated by CRD. The researchers concluded that the increase in CA, caused by drinking Pu-erh tea and reaching the fat tissue through blood circulation, could be a crucial mechanism to reduce obesity induced by circadian rhythm disorders.
Pu-erh tea and its ingredient theabrownin improve liver, jejunum, and adipose tissue functions in metabolic syndrome mice, modulating circadian rhythm, glycerophospholipid, and linoleic acid metabolism.
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In this study, varied technological applications such as metagenomics, transcriptomics, and metabolomics were utilized to explore the anti-metabolic syndrome mechanism of Pu-erh tea and theabrownin in mice with metabolic syndrome. These scientific technologies allowed the researchers to understand and explore improvements in the physiological functions of liver, jejunum, and adipose tissues in the metabolic syndrome mice as a result of Pu-erh tea and theabrownin interventions. The investigation also focused on changes to the hepatic transcriptome, revealing that both of these interventions had the capacity to regulate the circadian rhythm pathway.
The results showcased that both interventions succeeded in the modulation of glycerophospholipid and linoleic acid metabolism, this was established through a comprehensive analysis of serum and brain metabolome. Further analysis of faecal metagenome demonstrated an increase in the relative abundance of certain bacterium and a decrease in others due to both interventions. However, in comparison to Pu-erh tea, theabrownin exhibited a more pronounced influence as regards upregulating hepatic antioxidants and downregulating hepatic inflammatory factors, although there was only a slight reduction in obesity-linked short-chain fatty acids in faeces of the metabolic syndrome mice. Overall, the experiment provided essential insights into the various ways these two elements function and provide treatment for metabolic syndrome.
Pu-erh tea, with its complex components, interacts greatly with gut microbiomes and holds significant potential for healthcare applications.
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Pu-erh tea undergoes a post-fermentation process involving various microorganisms, leading to highly complex components. This tea has its potential benefit due to its rich interactions with the gut microbiomes; the structure and the homeostasis of which are deeply connected to human wellness and progress of various diseases. This study provides a systemic review of the current findings pertaining to the bioactive components of Pu-erh tea and their interactions with gut microbiomes.
For the discussion of results, the beneficial effects of Pu-erh tea on gut microbiomes may establish its role in healthcare. These benefits are due to the tea's bioactive components' impacts on the structure of the gut microbiomes, and subsequent health improvements. Additionally, the establishment of "components-function-indicators" clues can propel the standardisation of the tea's fermentation process and development of functional tea-related products.
The traditional Chinese medicine diagnosis of Cold and Hot Syndromes based on tongue-coating appearance successfully detects signals in the tongue-coating microbiomes that are indicators of the entire body's status.
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In summary, by studying the tongue-coating microbiomes of chronic atrophic gastritis patients and healthy controls using next-generation sequencing and bioinformatics analysis, we revealed the possible mechanism underlying the traditional tongue diagnosis and highlighted the potential for using tongue coating microbiome features as biomarkers to reflect the holistic status of the human body, especially in gastrointestinal diseases. The current sample size of this study is still small and further investigations with more samples and complete metagenome sequencing are needed for a comprehensive understanding of the system. The observations described here might provide a new direction for understanding the biological basis of TCM tongue diagnosis and the link between the “geographic tongue” and the human body's health status observed in modern Western medicine.
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These facts lend credibility to the Chinese custom of discarding the first preparation of the Pu-erh tea and using the damp tea for subsequent brewing.
—Jinnan C 10 Jan 2024