According to recent studies in individuals with a cluster of risk factors for heart disease, ingesting green tea extract for four weeks can lower blood sugar levels and enhance gut health by reducing inflammation and "leaky gut."
This study, according to researchers, is the first to examine whether the anti-inflammatory properties of green tea may have a protective effect against the health risks associated with metabolic syndrome, a condition that affects around one-third of Americans.
“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 at the gut to those health factors,” said Richard Bruno, senior study author and professor of human nutrition at The Ohio State University.
The clinical investigation, which involved 40 people, was a follow-up to a 2019 study that revealed improved gut health was connected with lower obesity and fewer health risks in mice that received green tea supplements.
Unexpectedly, the new study found that green tea extract also reduced gut inflammation and permeability in healthy individuals, as well as blood sugar, or glucose.
“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.
Recent publications in Current Developments in Nutrition include articles on the outcomes of the glucose study and decreased intestinal permeability and inflammation. 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, high levels of fasting blood glucose, and triglycerides, a form of blood fat—are present in people with metabolic syndrome.
According to Bruno, the problematic thing about these risk variables that make up metabolic syndrome is that they frequently just have minor changes and do not yet require pharmacological management, although still posing a serious risk to health.
“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, 40 participants—21 with metabolic syndrome and 19 healthy adults—consumed gummy candies containing green tea extract high in catechins, which are anti-inflammatory chemicals. Five cups of green tea made up the recommended daily intake. All participants in the randomised double-blind crossover trial took a placebo for a further 28 days, followed by a month without taking any supplements.
In order to ensure that any outcomes of the placebo and green tea extract confection phases of the study could be attributed to the effects of green tea alone, researchers confirmed that participants, as advised, followed a diet low in polyphenols — naturally occurring antioxidants in fruits, vegetables, teas, and spices.
As a result of eating green tea extract, all subjects’ fasting blood glucose levels were much lower than they were after taking the placebo, according to the results. An investigation that revealed a decrease in pro-inflammatory proteins in faecal samples was used to establish that the green tea treatment reduced intestinal inflammation in all subjects. Researchers also discovered that drinking green tea significantly reduced individuals’ small intestinal permeability using a method to analyse sugar ratios in urine samples.
Leaky gut, also known as gut permeability, allows intestinal bacteria and related harmful chemicals to enter the bloodstream, causing 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, 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.”
The levels of bacteria-related toxins in study participants’ blood are being completed by Bruno’s lab, as well as additional examinations of the microbial populations in their stomachs.
The Ohio Agricultural Research and Development Center at Ohio State and the United States Department of Agriculture both provided funding for this effort. In both papers, Min Zeng, Geoffrey Sasaki, Sisi Cao, Yael Vodovotz, and Joanna Hodges all contributed as co-authors from Ohio State. The paper on glucose reduction was also co-authored by Avinash Pokala and Shahabeddin Rezaei.