Gut-level Antiinflammatory Activities of Green Tea in Metabolic Syndrome

This study evaluates dietary green tea extract to improve gut health and inflammation in persons with metabolic syndrome and healthy adults. Participants will complete two phases of intervention in random order in which they will consume green tea extract or placebo for one month and then switch to the opposite treatment for an additional month.

Study Overview

• Status: Completed
• Conditions: Inflammation; Metabolic Syndrome; Endotoxemia; Dysbiosis
• Intervention / Treatment: Dietary supplement: Green Tea Extract; Dietary supplement: Placebo

Detailed Description

Tea is the most abundantly consumed prepared beverage in the world. Green tea, containing catechins, exerts antiinflammatory activities. However, a fundamental gap exists concerning its intestinal-level targets that can prevent metabolic syndrome (MetS) development and progression. Studies in obese rodents indicate that green tea inhibits nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) activation by limiting gut-derived endotoxin translocation to the portal circulation and decreasing hepatic Toll-like receptor-4 (TLR4) pro-inflammatory signaling. The objective of this clinical investigation is to establish evidence-based recommendations for green tea, based on improvements in endotoxemia and restored gut barrier function, that promote optimal health. The hypothesis is that green tea catechins function to limit metabolic endotoxemia by ameliorating gut dysbiosis-mediated inflammation that otherwise provokes intestinal permeability. This will be tested by conducting a double-blind, placebo-controlled, randomized-order, crossover trial in MetS and healthy persons to examine the efficacy of green tea on metabolic endotoxemia. Each treatment will be one-month in duration and separated by a washout period. The anticipated outcomes are expected to be of significance, because they will advance a dietary strategy to help avert MetS complications attributed to metabolic endotoxemia by establishing antiinflammatory prebiotic and antimicrobial bioactivities of catechins that promote intestinal health.

• Study Type: Interventional
• Enrollment (Actual): 46
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Ohio
    • Columbus, Ohio, United States, 43210
      • The Ohio State University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion criteria:

Individuals with ≥3 of the following established criteria for metabolic syndrome:

• Fasting glucose 100-126 mg/dL
• Waist circumference >89/>102 cm for females/males
• HDL-C <50/<40 mg/dL for females/males
• Triglyceride >150 mg/dL
• Blood pressure >130/85 mmHg

Healthy adults:

• Body weight 19-25 kg/m2
• Fasting glucose <100 mg/dL
• HDL-C >50/>40 mg/dL for females/males
• Triglyceride <150 mg/dL
• Blood pressure <120/80 mmHg

Exclusion criteria:

• Concurrent tea consumption
• Use of dietary supplements, prebiotics, or probiotics
• Use of antibiotics or antiinflammatory agents
• History of liver disease, cardiovascular disease, hypertension (blood pressure >140/90 mmHg), or cancer
• History of gastrointestinal disorders, chronic diarrhea, or surgeries
• Hemochromatosis
• Parkinson's disease
• Use of medications to manage diabetes, hypertension, or hyperlipidemia
• Use of antipsychotic medications [Clozapine, lithium, Diazepam]
• Use of blood thinning medications [Warfarin]
• Use of high blood pressure medications [nadolol]
• Use of monoamine oxidase inhibitors [selegiline]
• Alcohol consumption >2 drinks/d
• Smoking tobacco
• Vegetarian
• Pregnancy, lactation, or recent changes in birth control use for women

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Green Tea; Participants consuming gummy confections with catechin-rich green tea extract daily for 4 weeks	Dietary supplement: Green Tea Extract; A gummy confection with catechin-rich green tea extract (1 g/d); Other Names: Camellia sinesis plant extract
Placebo Comparator: Placebo; Participants consuming matched gummy confections formulated without green tea extract daily for 4 weeks	Dietary supplement: Placebo; A matched gummy confection formulated without green tea extract

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Serum Endotoxin	Data are biomarker fasting concentrations.	Day 28

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Plasma Lipopolysaccharide-binding Protein	Data are biomarker fasting concentrations	Day 28
Urinary Lactulose/Mannitol Ratio	Lactulose/mannitol ratio in urine collected 0-5 h post-ingestion of non-digestible sugar probes.	Day 28
Urinary Sucralose/Erythritol Ratio	Sucralose/Erythritol ratio measured in urine collected 0-24 h post-ingestion of non-digestible sugar probes	Day 28
Plasma Interleukin-6	Data are biomarker concentrations at fasting	Day 28
Fecal Calprotectin	Data are biomarker fecal concentrations, measured in samples pooled from specimens collected on Days 25-27 of the 28-day intervention.	Day 25-27 (pooled samples) of the 28-day intervention
Fecal Myeloperoxidase	Data are biomarker fecal concentrations, measured in samples pooled from specimens collected on Days 25-27 of the 28-day intervention.	Day 25-27 (pooled samples) of the 28-day intervention
Plasma Epigallocatechin Gallate	Data are plasma concentrations of epigallocatechin gallate	Day 28
Plasma Epicatechin	Data are plasma concentrations of epicatechin.	Day 28
Plasma Epicatechin Gallate	Data are plasma concentrations of epicatechin gallate.	Day 28
Plasma 3,4-γ-valerolactone	Data are biomarker concentrations at fasting	Day 28
Plasma 3,4,5-γ-Valerolactone	Data are biomarker concentrations at fasting	Day 28
Plasma Soluble Cluster of Differentiation-14	Data are biomarker concentrations at fasting	Day 28
Plasma Glucose	Data are biomarker concentrations at fasting	Day 28
Plasma Insulin	Data are biomarker concentrations at fasting	Day 28
Plasma Triglyceride	Data are biomarker concentrations at fasting	Day 28
Plasma Total Cholesterol	Data are biomarker concentrations at fasting	Day 28
Serum Alanine Transaminase	Data are biomarker concentrations at fasting	Day 28
Serum Aspartate Transaminase	Data are biomarker concentrations at fasting	Day 28
Blood Hematocrit	Data are biomarker concentrations at fasting	Day 28
Plasma Tumor Necrosis Factor-alpha	Data are biomarker fasting concentrations	Day 28
Fecal Butyrate	Data are biomarker concentrations in fecal samples, measured in samples pooled from specimens collected on Days 25-27 of the 28-day intervention.	Days 25-27 (pooled samples) of the 28-day intervention
Fecal Acetate	Data are biomarker concentrations in fecal samples, measured in samples pooled from specimens collected on Days 25-27 of the 28-day intervention.	Days 25-27 (pooled samples) of the 28-day intervention
Fecal Valeric Acid	Data are biomarker concentrations in fecal samples, measured in samples pooled from specimens collected on Days 25-27 of the 28-day intervention.	Day 25-27 (pooled samples) from the 28-day intervention
Fecal Hexanoic Acid	Data are biomarker concentrations in fecal samples, measured in samples pooled from specimens collected on Days 25-27 of the 28-day intervention.	Day 25-27 (pooled samples) from the 28-day intervention
Fecal Isobutyric Acid	Data are biomarker concentrations in fecal samples, measured in samples pooled from specimens collected on Days 25-27 of the 28-day intervention.	Day 25-27 (pooled samples) from the 28-day intervention
Fecal 2-Methylbutyric	Data are biomarker concentrations in fecal samples, measured in samples pooled from specimens collected on Days 25-27 of the 28-day intervention.	Day 25-27 (pooled samples) of the 28-day intervention
Fecal Isovaleric Acid	Data are biomarker concentrations in fecal samples, measured in samples pooled from specimens collected on Days 25-27 of the 28-day intervention.	Day 25-27 (pooled samples) of the 28-day intervention
Plasma Ascorbic Acid	Data are biomarker fasting concentrations	Day 28
Plasma Uric Acid	Data are biomarker fasting concentrations	Day 28

Collaborators and Investigators

• Sponsor: Ohio State University
• Collaborators: United States Department of Agriculture (USDA)
• Investigators: Principal Investigator: Richard S Bruno, PhD, RD, Ohio State University

Publications and helpful links

General Publications

• Dey P, Sasaki GY, Wei P, Li J, Wang L, Zhu J, McTigue D, Yu Z, Bruno RS. Green tea extract prevents obesity in male mice by alleviating gut dysbiosis in association with improved intestinal barrier function that limits endotoxin translocation and adipose inflammation. J Nutr Biochem. 2019 May;67:78-89. doi: 10.1016/j.jnutbio.2019.01.017. Epub 2019 Feb 8.
• Li J, Sasaki GY, Dey P, Chitchumroonchokchai C, Labyk AN, McDonald JD, Kim JB, Bruno RS. Green tea extract protects against hepatic NFkappaB activation along the gut-liver axis in diet-induced obese mice with nonalcoholic steatohepatitis by reducing endotoxin and TLR4/MyD88 signaling. J Nutr Biochem. 2018 Mar;53:58-65. doi: 10.1016/j.jnutbio.2017.10.016. Epub 2017 Nov 3.
• Hodges JK, Zhu J, Yu Z, Vodovotz Y, Brock G, Sasaki GY, Dey P, Bruno RS. Intestinal-level anti-inflammatory bioactivities of catechin-rich green tea: Rationale, design, and methods of a double-blind, randomized, placebo-controlled crossover trial in metabolic syndrome and healthy adults. Contemp Clin Trials Commun. 2019 Nov 20;17:100495. doi: 10.1016/j.conctc.2019.100495. eCollection 2020 Mar.
• Zeng M, Hodges JK, Pokala A, Khalafi M, Sasaki GY, Pierson J, Cao S, Brock G, Yu Z, Zhu J, Vodovotz Y, Bruno RS. 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. Nutr Res. 2024 Apr;124:94-110. doi: 10.1016/j.nutres.2024.02.001. Epub 2024 Feb 5.

Study record dates

Study Major Dates

• Study Start (Actual): July 1, 2019
• Primary Completion (Actual): March 1, 2021
• Study Completion (Actual): March 1, 2021

Study Registration Dates

• First Submitted: May 30, 2019
• First Submitted That Met QC Criteria: June 3, 2019
• First Posted (Actual): June 4, 2019

Study Record Updates

• Last Update Posted (Estimated): December 19, 2025
• Last Update Submitted That Met QC Criteria: December 3, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Inflammation; Microbiome; Metabolic syndrome; Gut barrier function; Green tea; Gut dysbiosis; Metabolic endotoxemia
• Additional Relevant MeSH Terms: Pathologic Processes; Metabolic Diseases; Infections; Sepsis; Systemic Inflammatory Response Syndrome; Glucose Metabolism Disorders; Insulin Resistance; Hyperinsulinism; Bacteremia; Toxemia; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Metabolic Syndrome; Inflammation; Dysbiosis; Endotoxemia; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages; Beverages; Plant Preparations; Biological Products; Complex Mixtures; Tea
• Other Study ID Numbers: 2018H0592

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No