A green tea extract confection decreases circulating endotoxin and fasting glucose by improving gut barrier function but without affecting systemic inflammation: A double-blind, placebo-controlled randomized trial in healthy adults and adults with metabolic syndrome.

2024-04
Nutrition research (New York, N.Y.) 124
- Min Zeng
- Joanna K Hodges
- Avinash Pokala
- Mona Khalafi
- Geoffrey Y Sasaki
- Jillian Pierson
- Sisi Cao
- Guy Brock
- Zhongtang Yu
- Jiangjiang Zhu
- Yael Vodovotz
- Richard S Bruno

PubMed: 38430822
DOI: 10.1016/j.nutres.2024.02.001

Study Design

Type: Randomized Controlled Trial (RCT)
Sample size: n = 21
Population: healthy adults (n = 19, 34 ± 2 years) and adults with MetS (n = 21, 40 ± 3 years)
Methods: Randomized, double-blind, placebo-controlled, crossover trial, 4-week administration of decaffeinated GTE confection (890 mg/d total catechins)
Blinding: Double-blind
Duration: 4 weeks
Funding: Unclear

Anti-inflammatory activities of catechin-rich green tea extract (GTE) in obese rodents protect against metabolic endotoxemia by decreasing intestinal permeability and absorption of gut-derived endotoxin. However, translation to human health has not been established. We hypothesized that GTE would reduce endotoxemia by decreasing gut permeability and intestinal and systemic inflammation in persons with metabolic syndrome (MetS) compared with healthy persons. A randomized, double-blind, placebo-controlled, crossover trial in healthy adults (n = 19, 34 ± 2 years) and adults with MetS (n = 21, 40 ± 3 years) examined 4-week administration of a decaffeinated GTE confection (890 mg/d total catechins) on serum endotoxin, intestinal permeability, gut and systemic inflammation, and cardiometabolic parameters. Compared with the placebo, the GTE confection decreased serum endotoxin (P = .023) in both healthy persons and those with MetS, while increasing concentrations of circulating catechins (P < .0001) and γ-valerolactones (P = .0001). Fecal calprotectin (P = .029) and myeloperoxidase (P = .048) concentrations were decreased by GTE regardless of health status. Following the ingestion of gut permeability probes, urinary lactose/mannitol (P = .043) but not sucralose/erythritol (P > .05) was decreased by GTE regardless of health status. No between-treatment differences (P > .05) were observed for plasma aminotransferases, blood pressure, plasma lipids, or body mass nor were plasma tumor necrosis factor-α, interleukin-6, or the ratio of lipopolysaccharide-binding protein/soluble cluster of differentiation-14 affected. However, fasting glucose in both study groups was decreased (P = .029) by the GTE confection compared with within-treatment arm baseline concentrations. These findings demonstrate that catechin-rich GTE is effective to decrease circulating endotoxin and improve glycemic control in healthy adults and those with MetS, likely by reducing gut inflammation and small intestinal permeability but without affecting systemic inflammation.

Research Insights

Camellia→Improved Intestinal Epithelial Permeability
Following the ingestion of gut permeability probes, urinary lactose/mannitol (P = .043) but not sucralose/erythritol (P > .05) was decreased by GTE regardless of health status.
Effect
Beneficial
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Aminotransferase Level
No between-treatment differences (P > .05) were observed for plasma aminotransferases, blood pressure, plasma lipids, or body mass
Effect
Neutral
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Blood Pressure
No between-treatment differences (P > .05) were observed for plasma aminotransferases, blood pressure, plasma lipids, or body mass
Effect
Neutral
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Body Mass
No between-treatment differences (P > .05) were observed for plasma aminotransferases, blood pressure, plasma lipids, or body mass
Effect
Neutral
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Circulating Endotoxin
Compared with the placebo, the GTE confection decreased serum endotoxin (P = .023) in both healthy persons and those with MetS.
Effect
Beneficial
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Colonic Permeability
Following the ingestion of gut permeability probes, urinary lactose/mannitol (P = .043) but not sucralose/erythritol (P > .05) was decreased by GTE regardless of health status.
Effect
Neutral
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Faecal Calprotectin
Fecal calprotectin (P = .029) and myeloperoxidase (P = .048) concentrations were decreased by GTE regardless of health status.
Effect
Beneficial
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Fasting Blood Glucose Levels
However, fasting glucose in both study groups was decreased (P = .029) by the GTE confection compared with within-treatment arm baseline concentrations.
Effect
Beneficial
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Fecal Myeloperoxidase
Fecal calprotectin (P = .029) and myeloperoxidase (P = .048) concentrations were decreased by GTE regardless of health status.
Effect
Beneficial
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Interleukin-6 Levels
No between-treatment differences (P > .05) were observed for plasma tumor necrosis factor-α, interleukin-6, or the ratio of lipopolysaccharide-binding protein/soluble cluster of differentiation-14 affected.
Effect
Neutral
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Lipid Level
No between-treatment differences (P > .05) were observed for plasma aminotransferases, blood pressure, plasma lipids, or body mass
Effect
Neutral
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Lipopolysaccharide-binding Protein/Soluble Cluster of Differentiation-14 Ratio
No between-treatment differences (P > .05) were observed for plasma tumor necrosis factor-α, interleukin-6, or the ratio of lipopolysaccharide-binding protein/soluble cluster of differentiation-14 affected.
Effect
Neutral
Effect size
Small
Dose
890 mg/d total catechins
Camellia→Reduced Tumor Necrosis Factor Alpha
No between-treatment differences (P > .05) were observed for plasma tumor necrosis factor-α, interleukin-6, or the ratio of lipopolysaccharide-binding protein/soluble cluster of differentiation-14 affected.
Effect
Neutral
Effect size
Small
Dose
890 mg/d total catechins