Green tea extract may help lower blood sugar and improve gut health, scientists say

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A recent study found that green tea extract supplements can promote gut health and lower blood glucose levels in both healthy adults and those with metabolic syndrome.

Published in the journal, Current Developments in Nutrition, the study aimed to determine whether catechin-rich green tea extract could alleviate intestinal inflammation related to cardiometabolic risk in people with metabolic syndrome, a hypothesis established by preclinical evidence.

Led by Richard Bruno, PhD, Msc, professor of human nutrition at The Ohio State University in Columbus, Ohio, a team of researchers studied the effects of green tea extract on blood glucose, gut inflammation, and gut permeability. Included in the study were 40 participants, 21 of which were diagnosed with metabolic syndrome. The other 19 were considered healthy adults.

Participants consumed a green tea extract gummy, with a dose equal to five cups of green tea, once a day for 28 days. The participants also took a placebo for 28 days, with a month off between treatments. Researchers advised participants to follow a diet low in polyphenols, naturally occurring antioxidants in fruits, vegetables, teas, and spices, as to not muddle results.

Results showed that fasting blood glucose levels were significantly reduced in all participants. In addition, researchers found that all participants had decreased gut inflammation through an analysis of pro-inflammatory proteins in fecal samples. Small intestine permeability, assessed through sugar ratios in urine samples, also decreased among participants after taking the green tea extract gummy.

According to the study’s authors, gut permeability, also known as leaky gut, allows 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," said Bruno in a statement. "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.”

These results, according to authors, indicate that green extract supplements have the potential to greatly improved metabolic syndrome outcomes.

"We did not attempt to cure metabolic syndrome with a one-month study," Bruno stated. "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."