New research in people with a range of risk factors for heart disease has shown that consuming green tea extract for four weeks can reduce blood sugar levels and improve gut health by reducing inflammation and reducing “leaky gut”. “.
The researchers said this is the first study to assess whether the health risks associated with the condition known as metabolic syndrome, which affects about a third of Americans, can be reduced by green tea’s anti-inflammatory benefits to the gut.
“There is a lot of evidence that higher consumption of green tea is associated with better cholesterol, glucose and triglyceride levels, but no studies have linked its gut benefits to these health factors,” said Richard Bruno, senior author of the study. and professor of man. in nutrition at The Ohio State University.
The team conducted the clinical test in 40 individuals as a follow-up to a 2019 study that linked lower obesity and fewer health risks in mice consuming green tea supplements with improvements in gut health.
In the new study, green tea extract also lowered blood sugar, or glucose, and reduced gut inflammation and permeability in healthy people—an unexpected finding.
“What this tells us is that within a month we are able to lower blood glucose in both people with metabolic syndrome and in healthy people, and the reduction in blood glucose appears to be associated with a reduction in leaky gut. and reducing gut inflammation — regardless of health status,” said Bruno.
Articles on glucose outcomes and decreased intestinal permeability and inflammation were recently published in Current developments in nutrition.
People with metabolic syndrome are diagnosed with at least three of the five factors that increase their risk for heart disease, diabetes and other health problems: excess belly fat, high blood pressure, low HDL (good) cholesterol and levels of high blood glucose. and triglycerides, a type of fat in the blood.
The tricky thing about these risk factors that make up the metabolic syndrome is that they often change little and don’t yet require drug management, but still impose great health risk, Bruno said.
“Most doctors will recommend weight loss and exercise first. Unfortunately, we know that most people cannot comply with lifestyle modifications for a variety of reasons,” he said. “Our work aims to give people a new food-based tool to help manage their risk for metabolic syndrome or reverse metabolic syndrome.”
Forty participants — 21 with metabolic syndrome and 19 healthy adults — consumed gummies containing green tea extract rich in anti-inflammatory compounds called catechins for 28 days. The daily dose was equivalent to five cups of green tea. In the randomized double-blind crossover trial, all participants spent an additional 28 days taking a placebo, with a month off from each supplement between treatments.
The researchers confirmed that the participants, as advised, followed a diet low in polyphenols – natural antioxidants in fruits, vegetables, teas and spices – during the placebo and green tea extract confection phases of the study, so any results could ‘attributable to the effects. only from green tea.
The results showed that fasting blood glucose levels for all participants were significantly lower after taking green tea extract compared to levels after taking a placebo. The reduction of intestinal inflammation due to green tea treatment in all participants was ascertained through an analysis that showed a reduction of pro-inflammatory proteins in the stool samples. Using a technique to assess sugar ratios in urine samples, the researchers also found that with green tea, the permeability of the participants’ small intestines was favorably decreased.
Gut permeability, or leaky gut, allows gut bacteria and associated toxic compounds to enter the bloodstream, stimulating chronic low-grade inflammation.
“That absorption of gut-derived products is thought to be an initiating factor for obesity and insulin resistance, which are central to all cardiometabolic disorders,” Bruno said. “If we can improve gut integrity and reduce leaky gut, it’s thought we’ll be able to not only alleviate the low-grade inflammation that initiates cardiometabolic disorders, but potentially reverse them.
“We didn’t try to cure metabolic syndrome with a one-month study,” he said. “But based on what we know about the causative factors behind metabolic syndrome, there is potential for green tea to act at least in part at the gut level to alleviate the risk of developing it or to reverse it if you already have metabolic syndrome. “
Bruno’s lab is completing further analyzes of the microbial communities in the study participants’ guts and the levels of bacteria-related toxins in their blood.
This work was supported by the US Department of Agriculture and the Ohio State Agricultural Research and Development Center.
Ohio State co-authors of both papers include Min Zeng, Geoffrey Sasaki, Sisi Cao, Yael Vodovotz and Joanna Hodges. Avinash Pokala and Shahabeddin Rezaei also co-authored the paper on glucose reduction.