Figures (4)  Tables (2)

    • Figure 1. 

      Lifestyle and dietary patterns are related to CMDs (created with BioRender.com).

    • Figure 2. 

      The main components of tea polyphenols.

    • Figure 3. 

      Enzymatic oxidation of catechins leading to the formation of theaflavins (TFs).

    • Figure 4. 

      The improving effect of tea catechins and their polymers on metabolic diseases: pharmacology and mechanism.

    • Diseases Specific compound/
      extract used      		 Activity/mechanism(s) of action Cell lines/model Dose Application (route of amelioration) Reference
      T2DM Green tea polyphenols and different tea types Inhibiting α-glucosidase activity 2.33 µg/mL; 0.25–0.016 mg/mL [20]
      EGCG Reduces blood glucose and improves insulin resistance and islet β-cell disorder High-sucrose high-fat diet (HFD) with streptozotocin-induced diabetic rats 25, 50,
      100 mg/kg/d      		 In vivo (oral gavage) [21]
      EGCG Alleviates high glucose-induced pancreatic β-cell dysfunction by targeting the DRP1-related mitochondrial apoptosis pathway MIN6 cells 10, 20, 40 μM In vitro [22]
      EGCG Inhibitor of NLRP3 inflammasome activation; improves glucose tolerance Mouse bone marrow-derived macrophages; HFD mice 20, 30, 40 μM;
      50 mg/kg      		 In vitro; in vivo (oral gavage) [23]
      (-)-Epicatechin Modulates the gut microbiota and liver insulin signaling pathways HFD rats 40, 80 mg/kg In vivo (oral gavage) [24]
      EGCG-derived oxidation products Activation of the beneficial axis of RAS and suppression of the deleterious axis of RAS, SELENOP, TXNIP, or renal PEPCK/G6Pase-α db/db mice 5, 10, 40 mg/kg In vivo (intraperitoneal injection) [25]
      Theaflavins (TFs) Promoting mitochondrial biogenesis and improving the hepatocellular insulin resistance induced by free fatty acids HepG2 cells 2.5, 5, 10 μg/mL In vitro [26]
      Theabrownin (TB) from Fu Brick tea Altering the gut microbiota and improving intestinal tight junction integrity HFD mice 100, 200,
      400 mg/kg      		 In vivo (oral gavage) [28]
      Obesity Green tea polyphenols Changing the composition and diversity of colonic microbiota HFD mice Diet supplemented with 0.05, 0.2, 0.8% In vivo [42]
      Green tea polyphenol extract Promoting the induction of thermogenic cells by reprogramming the initial steps of adipocyte commitment Cafeteria diet mice 500 mg/kg In vivo (oral gavage) [43]
      Green tea polyphenol extract Inducing adaptive thermogenesis and browning in scWAT HFD mice 500 mg/kg In vivo (oral gavage) [44]
      Green tea polyphenols Inhibition of erk1/2 activation, alleviation of PPARγ phosphorylation, and increased PPARγ expression HFD rats Drinking water supplemented with 0.8, 1.6,
      3.2 g/L      		 In vivo [45]
      Polyphenol-enriched oolong tea Increases lipid excretion into feces Healthy adult subjects 19.3 ± 12.9 g/3 d In vivo [46]
      EGCG Increases the expression of hepatic TGR5 and decreases the expression of intestinal FXR-FGF15 HFD rats 40, 160 mg/kg In vivo (oral gavage) [47]
      EGCG Induces fat deposition by targeting HSP70 through the activation of AMPK–SIRT1–PGC-1α in porcine subcutaneous preadipocytes Porcine subcutaneous preadipocytes 100 μM In vitro [48]
      EGCG Downregulated MAPK7 mRNA and protein levels time- and dose-dependently 3T3-L1 cells 10, 20, 50 μM In vitro [49]
      EGCG Upregulation of Beclin1-dependent autophagy and lipid catabolism in WAT HFD mice 20 mg/kg In vivo (oral gavage) [50]
      EGCG Promotes fat oxidation HFD mice Diet supplemented with 0.5, 1% In vivo [51]
      Oxidized tea polyphenols (OTPs) Alleviates the accumulation of lipids in liver and visceral white adipose tissue and promotes lipid excretion HFD rats Diet supplemented with 2% In vivo [53]
      MASLD Green tea extract (GTE) Prevents dietary-induced liver steatosis HFD rats Diet supplemented with 1.1, 2% In vivo [65]
      EGCG Possesses a Bmal1-dependent efficacy against insulin resistance conditions by strengthening insulin signaling and eliminating oxidative stress HepG2 cells/primary hepatocytes 0, 25, 50, 100 μM In vitro [66]
      Tea polyphenols and EGCG Promoting acid-producing bacteria HFD rats 200, 400,
      800 mg/kg      		 In vivo (oral gavage) [67]
      EGCG Decreases bile acid reabsorption HFD mice Diet supplemented with 0.32% In vivo [68]
      Green tea extract rich in EGCG Activation of AMPK via LKB1 in the liver HFD mice 50 mg/kg In vivo (oral gavage) [70]
      AS EGCG Mediated by AP-1 inactivation through ERK and JNK Human primary T cells 0.1, 1, 5, 10, 20 μM In vitro [81]
      (-)-Epicatechin gallate (ECG) Inhibition of the phosphorylation of p65 in the NF-κB pathway in the aorta VSMCs;
      HFD mice      		 10, 20, 50 μM;
      5, 25, 50 mg/kg      		 In vitro; in vivo (intraperitoneal Injection) [82]
      (-)-Epicatechin gallate (ECG) Inhibition of intracellular NF-κB signaling pathway proteins and activation of the HO-1/Nrf2 signaling pathway [83]
      Tea polyphenols Promoting the proliferation of the intestinal Bifidobacteria HFD mice Drinking water supplemented with 0.4, 0.8,
      1.6 g/L      		 In vivo [84]
      Green tea, black tea Antioxidant properties of the intervention HFD rabbits 200 mg/kg In vivo [85]
      Green tea polyphenols Increasing the mRNA and protein expression levels of hepatic PPARα and autophagy markers HFD-fed male ApoE-knockout mice Drinking water supplemented with 3.2, 6.4 g/L In vivo [86]
      Hyperuricemia Green tea polyphenols Decreasing uric acid production and increasing uric acid excretion PO-induced hyperuricemic mice 300, 600 mg/kg In vivo (oral gavage) [93]
      EGCG Inhibition of XOD activity and GLUT9 expression and the promotion of OAT1 expression BRL 3A rat liver cells;
      PO-induced hyperuricemic mice      		 10, 20, 40 µM;
      25, 50, 100 mg/kg      		 In vitro; in vivo (oral gavage) [95]
      Fermented tea extracts Inhibition of xanthine oxidase activities LO-2 cells 0.12, 2 mg/mL In vitro [97]
      Pu-erh tea polyphenols Reshaping the gut microbiota CRD-induced hyperuricemic mice In vivo [98]

      Table 1. 

      Pharmacology of tea catechins and their polymers.

    • Shared mechanism Key molecular targets/pathways Representative tea components
      Insulin resistance AMPK, IRS-1/PI3K/Akt, GLUT4, PPARγ EGCG, theaflavins, green tea catechins
      Inflammation NLRP3 Inflammasome, NF-κB, TNF-α, IL-6 EGCG, ECG, theaflavins
      Oxidative stress Nrf2/HO-1, SOD, MDA ECG, EGCG, theaflavins
      Gut microbiota dysbiosis Microbiota composition, SCFAs, intestinal FXR/FGF19, bile acids EGCG, EC, theabrownins, green tea catechins

      Table 2. 

      Summary of the key shared pharmacological targets of tea catechins and their polymers.