Green tea extract improves gut health and lowers blood sugar

Summary: For people with heart disease risk factors, daily use of green tea extract can lower blood sugar levels and improve gut health by reducing inflammation and “leaky gut.” Green tea extract may be effective in reducing some of the risks of metabolic syndrome.

A source: The Ohio State University

New research in people with a cluster of heart disease risk factors shows that drinking green tea extract for four weeks lowers blood sugar levels and improves gut health by reducing inflammation and “leaky gut.”

Researchers say this is the first study to evaluate whether the health risks associated with a condition known as metabolic syndrome, which affects about a third of Americans, may be mitigated by green tea’s anti-inflammatory benefits in the gut.

“There is a lot of evidence that higher consumption of green tea is associated with better levels of cholesterol, glucose and triglycerides, but no studies have linked its gut benefits to other health factors,” said Richard Bruno, senior study author and professor. Dining at The Ohio State University.

The team conducted a clinical trial in 40 people as a follow-up to a 2019 study that linked improved gut health to mice that consumed green tea supplements and decreased health.

In a new study, green tea extract also lowered blood sugar, or glucose, and reduced gut inflammation and permeability in healthy people—an unexpected finding.

“This shows us that we can lower blood glucose over a month in both people with metabolic syndrome and healthy people, and that lower blood glucose seems to be associated with less leaky gut and less inflammation in the gut, regardless of the health condition,” Bruno said.

Articles on glucose outcomes and reduced intestinal permeability and inflammation have recently been published Current Developments in Nutrition.

People with metabolic syndrome are diagnosed with at least three of the five factors that increase their risk of heart disease, diabetes and other health problems — excess belly fat, high blood pressure, low HDL (good) cholesterol, and high levels of fasting glucose and triglycerides, a fat in the blood. a type.

The tricky thing about these risk factors that make up metabolic syndrome is that they often change only slightly and don’t require medication management, but still pose a major health risk, Bruno said.

“Most doctors recommend losing weight and exercising first. “Unfortunately, we know that most people can’t commit to lifestyle changes for various reasons,” he said. “Our work aims to provide a new food-based tool to help people manage their risk of metabolic syndrome or reverse metabolic syndrome.”

Forty participants – 21 people with metabolic syndrome and 19 healthy adults – consumed gummies containing green tea extract, which is rich in anti-inflammatory compounds called catechins, for 28 days. The daily dose is equivalent to five cups of green tea. In a randomized double-blind crossover trial, all participants took a placebo for another 28 days, with a month off from taking any supplements between treatments.

The researchers confirmed that during the placebo and green tea extract confection phases of the study, participants ate diets low in polyphenols (natural antioxidants in fruits, vegetables, teas, and spices), so the different results may have been due to the effects of green tea. tea alone.

The results showed that for all participants, blood glucose levels were significantly lower after taking the green tea extract than after taking a placebo. In all participants, treatment with green tea showed a reduction in intestinal inflammation, as determined by analysis of a decrease in pro-inflammatory proteins in fecal samples.

Using a method of measuring the amount of sugar in urine samples, the researchers found that participants with green tea had a better reduction in small intestinal permeability.

In a new study, green tea extract also lowered blood sugar, or glucose, and reduced gut inflammation and permeability in healthy people—an unexpected finding. Image is in the public domain

A leaky gut, or leaky gut, allows intestinal bacteria and related toxins to enter the bloodstream, stimulating low-grade chronic inflammation.

“Intestinal absorption is a predisposing factor for obesity and insulin resistance, which are central to all cardiometabolic disorders,” Bruno said. “We think that if we can improve gut integrity and reduce leaky gut, we can not only reduce the low-grade inflammation that drives cardiometabolic disorders, but reverse them.

“We’re not trying to cure metabolic syndrome with a one-month study,” he said. “But based on what we know about the causes of metabolic syndrome, green tea may act at least partially at the gut level to reduce the risk of developing or reverse metabolic syndrome if you have it. “

Bruno’s lab is completing further analysis of the microbial communities in the study participants’ guts and the levels of bacteria-related toxins in their blood.

Funding: This work was supported by the U.S. Department of Agriculture and the Ohio Agricultural Research and Development Center, Ohio.

Co-authors on both Ohio State papers include Ming Zeng, Jeffrey Sasaki, Sissy Cao, Yael Vodowoc and Joanna Hodges. Avinash Pokala and Shahabeddin Rezaei also co-authored the paper on glucose reduction.

Neuroscience research news about it

Author: Emily Caldwell
A source: The Ohio State University
The connection: Emily Caldwell – Ohio State University
Photo: Image is in the public domain

Original research: Open access.
Richard Bruno et al. Current Developments in Nutrition

See also

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Catechin-rich green tea extract reduced intestinal inflammation and fasting glucose in metabolic syndrome and healthy adults: A randomized, controlled, crossover trial.


Preclinical evidence has shown that catechin-rich green tea extract (GTE) improves gut barrier function and reduces intestinal and systemic inflammation. Thus, this clinical trial was conducted to test the hypothesis that GTE reduces intestinal inflammation relative to cardiometabolic risk in individuals with metabolic syndrome (MetS).


We conducted a randomized, double-blind, placebo-controlled, crossover trial in adults with MetS and healthy subjects who received no (placebo) or 1 g/d GTE (890 mg catechin) confections for 28 days. by maintaining a low polyphenol diet. Dietary polyphenols, fasting blood glucose, insulin, and lipids were assessed on d 0, 14, and 28 of each intervention. Intestinal inflammation was assessed by measuring neutrophil-derived calprotectin and myeloperoxidase by ELISA in stool samples collected during the last 3 days of each intervention. Data were analyzed using RM ANOVA and multiple linear regression.


MetS (n = 21; 40 ± 3 y; 35 ± 1 kg/mtwo) and healthy (n = 19; 34 ± 2 y; 22 ± 0.4 kg/mtwo) people completed the study with high compliance (>95%), no side effects or changes in body mass. Participants’ total polyphenol intakes decreased during each intervention compared to baseline (P < 0.001). Faecal calprotectin and myeloperoxidase were lower in GTE compared with placebo regardless of health status (P < 0.05). Although fasting insulin, triglycerides, total and high-density lipoprotein cholesterol were not affected by treatment, fasting glucose decreased in response to GTE regardless of health status (P < 0.01). Adverse changes in age (β = -0.29; P = 0.05) and myeloperoxidase (β = 0.03; P < 0.04) predicted changes in insulin after controlling for sex, waist circumference, and changes in blood lipids and calprotectin.


A dietary intervention with GTE-rich confections in weight-stable healthy and MetS adults reduced fasting glucose and intestinal inflammation associated with improvements in fasting insulin. This suggests that GTE can improve glycemic control by reducing gut inflammation, contributing to an increase in insulin sensitivity.

Funding sources

USDA-NIFA, USDA-HATCH, and the Ohio Agricultural Research and Development Center at Ohio State University.

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