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 can potentially prevent depression-like behaviors induced by nighttime blue light from electronic devices by reshaping gut microbiota and increasing short-chain fatty acids generation.
2023 Food & Function Long-term Pu-erh tea consumption improves blue light-induced depression-like behaviors Zhao S, Hu S, Sun K, Luo L, Zeng L
Experimental Study Depression katana Pu-Erh Tea
The methodology used involved administering water or Pu-erh tea to two groups of mice for 120 days, followed by a 45-day exposure to a blue light simulating electronic equipment during the night. The effect of the tea and blue light on the mice's behavior and gut microbiota was then studied. Results indicated that the blue light induced depression-like behaviors and upset the gut microbiota in mice that were previously healthy.
In the discussion of results, it was noted that the intake of Pu-erh tea significantly reshaped the mice's gut microbiota, especially the metabolism of short-chain fatty acids, which helped protect the integrity of the intestinal barrier. This improvement not only lessened damage to the blood-brain barrier, but also reduced neuroinflammation by inhibiting certain cellular pathways. This ultimately regulated neurotransmitters like brain-derived neurotrophic factor and serotonin, demonstrating the potential of Pu-erh tea to prevent blue light induced depression-like behaviors by impacting the gut-brain axis.
Pu-erh tea possesses therapeutic mechanisms potentially beneficial for metabolic diseases due to its interaction with liver and gut microbiome.
2022 Journal of Traditional Chinese Medical Sciences Pu-erh tea: A review of a healthful brew Jia W, Rajani C, Lv A, Fan TP, Zheng X
Review Article Gut Microbiota Metabolic Syndrome Pu-Erh Tea
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 may prevent circadian rhythm disorders by promoting tryptophan metabolism and signaling interactions in the gut-liver-brain axis.
2022 Journal of Agricultural and Food Chemistry Pu-erh Tea Restored Circadian Rhythm Disruption by Regulating Tryptophan Metabolism Hu S, Luo L, Bian X, Liu RH, Zhao S, Chen Y, et al.
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Healthy mice were administered water or 0.25% Pu-erh tea over a period of seven weeks, and then subjected to a disruption of their light/dark cycle for forty days. The assessment of effects was based on changes in neurotransmitter secretion and gene oscillations, intestinal inflammation, and the balance of intestinal microbes and metabolites.
Results indicated that Pu-erh tea had beneficial impacts in regulating neurotransmitter secretion and clock gene oscillations, especially indole and 5-hydroxytryptamine pathways, a key process involving the gut-liver-brain axis. Moreover, the tea's metabolites improved release of brain hormones, thus enhancing hepatic glycolipid metabolism and lowering intestinal oxidative stress. Further observed beneficial effects included promotion of liver lipid metabolism and reduction of intestinal inflammation, via the enterohepatic circulation.
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.
2022 Food Chemistry Pu-erh tea increases the metabolite Cinnabarinic acid to improve circadian rhythm disorder-induced obesity Hu S, Hu C, Luo L, Zhang H, Zhao S, Liu Z, et al.
Experimental Study Cinnabarinic Acid Circadian Rhythm Gut Microbiota
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.
2022 Food Research International Pu-erh tea and theabrownin ameliorate metabolic syndrome in mice via potential microbiota-gut-liver-brain interactions Hou Y, Zhang Z, Cui Y, Peng C, Fan Y, Tan C, et al.
Animal Study Circadian Rhythm Gut Microbiota Metabolic Syndrome
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.
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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