Green tea extract improves gut health, lowers blood sugar level: Study

According to a new study on adults with a cluster of heart disease risk factors, using green tea extract for four weeks can reduce blood sugar levels and improve gut health by decreasing inflammation and “leaky gut.”

The study’s findings were published in the journal ‘Current Developments in Nutrition.’ According to the researchers, this is the first study to look at whether the health risks associated with metabolic syndrome, which affects around one-third of Americans, may be mitigated by green tea’s anti-inflammatory properties in the stomach.

“There is much evidence that greater consumption of green tea is associated with good levels of cholesterol, glucose and triglycerides, but no studies have linked its benefits in the gut to those health factors,” said Richard Bruno, senior study author and professor of human nutrition at The Ohio State University.

The clinical experiment was undertaken in 40 people as a follow-up to a 2019 study that linked lower obesity and fewer health risks in mice who received green tea supplements with improved gut health.

Green tea extract significantly reduced blood sugar, or glucose, as well as intestinal inflammation and permeability in healthy adults, according to the new research.

“What this tells us is that within one month we’re able to lower blood glucose in both people with metabolic syndrome and healthy people, and the lowering of blood glucose appears to be related to decreasing leaky gut and decreasing gut inflammation – regardless of health status,” Bruno said.

People with metabolic syndrome have at least three of the five risk factors for heart disease, diabetes, and other health issues: excess belly fat, high blood pressure, low HDL (good) cholesterol, and high levels of fasting blood glucose and triglycerides, a form of fat in the blood.

The problematic thing about these risk variables that comprise metabolic syndrome is that they are frequently just slightly changed and do not yet necessitate pharmacological treatment, yet they nevertheless represent a significant danger to health, according to Bruno.

“Most physicians will initially recommend weight loss and exercise. Unfortunately, we know most persons can’t comply with lifestyle modifications for various reasons,” he said. “Our work is aiming to give people a new food-based tool to help manage their risk for metabolic syndrome or to reverse metabolic syndrome.”

For 28 days, forty individuals – 21 with metabolic syndrome and 19 healthy people – ate gummy confections containing green tea extract rich in anti-inflammatory chemicals known as catechins. The daily intake was equivalent to five cups of green tea. In the randomised double-blind crossover study, all individuals took a placebo for another 28 days, with a month off between treatments.

Researchers confirmed that participants, as advised, followed a diet low in polyphenols – naturally occurring antioxidants in fruits, vegetables, teas and spices – during the placebo and green tea extract confection phases of the study so any results could be attributed to the effects of green tea alone.

Results showed that fasting blood glucose levels for all participants were significantly lower after taking green tea extract compared to levels after taking the placebo. Decreased gut inflammation due to the green tea treatment in all participants was established through an analysis that showed a reduction in pro-inflammatory proteins in faecal samples. Using a technique to assess sugar ratios in urine samples, researchers also found that with green tea, participants’ small intestine permeability favourably decreased.

Gut permeability, or leaky gut, enables intestinal bacteria and related toxic compounds to enter the bloodstream, stimulating low-grade chronic 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, the thought is we’ll be able to not only alleviate low-grade inflammation that initiates cardiometabolic disorders but potentially reverse them.

“We did not attempt to cure metabolic syndrome with a one-month study,” he said. “But based on what we know about the causal factors behind metabolic syndrome, there is potential for green tea to be acting at least in part at the gut level to alleviate the risk for either developing it or reversing it if you already have metabolic syndrome.”