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The Prediabetes Nutritionist

Kombucha found to lower blood sugar in type 2 diabetes

Kombucha Found to Lower Blood Sugar in Type 2 Diabetes

Kombucha – a type of fermented tea – may lower fasting blood sugar in adults with type 2 diabetes, a new, small, randomised, double-blind study has found.

“We were able to provide preliminary evidence that a common drink could have an effect on diabetes. We hope that a much larger trial, using the lessons we learned in this trial, could be undertaken to give a more definitive answer to the effectiveness of kombucha in reducing blood glucose levels, and hence prevent or help treat type 2 diabetes,” Chagai Mendelson, MD and lead author of the study said in a press release.

The study, “Kombucha tea as an anti-hyperglycaemic agent in humans with diabetes – a randomized controlled pilot investigation, was published in Frontiers in Nutrition.

Diabetes occurs when the pancreas cannot produce insulin or when the body does not effectively use insulin. According to the International Diabetes Federation, 537 million people were living with diabetes in 2021, a figure that is projected to rise to 783 million by 2045. Diet and lifestyle changes are the cornerstone of management, leading researchers to investigate different foods and diet patterns to reduce risk and manage blood sugar in people with diabetes.

Kombucha, a probiotic beverage, is made by fermenting sweetened tea with a symbiotic mixture of bacteria and yeasts (SCOBY). People in many parts of Asia and Eastern Europe have consumed it for centuries for its taste and perceived healing and health benefits, including improving gut health and reducing the risk of heart disease, cancer and diabetes.  

“Some laboratory and rodent studies of kombucha have shown promise, and one small study in people without diabetes showed kombucha lowered blood sugar, but to our knowledge, this is the first clinical trial examining effects of kombucha in people with diabetes,” study author Dan Merenstein, M.D., professor of Human Sciences at Georgetown School of Health and of family medicine at Georgetown University School of Medicine said in a press release.

A total of 12 adults (mean age 57, 75% female and 50% African American) participated in the study. They were split into two groups; one group consumed kombucha and the other a similar-tasting placebo drink with dinner daily for four weeks. After a break of eight weeks (to ‘wash out’ the effects of the first drink), the groups swapped drinks and continued drinking them daily with dinner for another four weeks. Participants recorded their morning blood glucose (before breakfast) with a glucose meter at specific time points during the study.

The scientists also assessed the genetic makeup of the bacteria and yeasts in kombucha to determine which were the most active.

Effectiveness of Kombucha tea in adults with type 2 diabetes.

Kombucha significantly lowered fasting blood sugar after four weeks from 164 to 116 mg/dL, but the placebo drink did not. However, the difference was not statistically significant when participants’ blood sugar levels were compared after four weeks of kombucha and the placebo. The researchers felt it was likely because two participants had well-controlled fasting blood sugars, that is, blood sugar within the recommended target range of 80-130 mg/dL or 4-7 mmol/mol for people with diabetes. After excluding those participants, the difference in blood sugar four weeks after kombucha and the placebo reached statistical significance.

The most active microorganisms in kombucha were acetic and lactic acid–producing bacteria and a yeast called Dekkera. Of note, acetic acid is reported to have anti-diabetes properties.

Possible Ways Kombucha Improves Blood Sugar

The possible ways kombucha improves blood sugar are inferred from animal studies since human studies are limited. Kombucha restores the beta (insulin-producing) cells in the pancreas, potentially increasing insulin release. The bacteria and yeasts in kombucha produce beneficial compounds, including antioxidants that reduce oxidative stress and the risk of chronic diseases like heart disease and diabetes. Finally, kombucha contains anti-diabetic acetic acid and other components that reduce starch digestion and glucose absorption.

The researchers highlighted limitations to the study, including its small size and high drop-out rate.

A lot more research needs to be done, but this is very promising,” Dan Merenstein, MD., professor of Human Sciences in Georgetown’s School of Health and family medicine at Georgetown University School of Medicine, said.

The Bottom Line

In this small study, kombucha lowered fasting blood sugar in adults with uncontrolled type 2 diabetes. However, the study is too small to be conclusive and larger studies must be done to corroborate the findings.  

Note: Somi Igbene – The Prediabetes Nutritionist is strictly an information and research website about nutrition, prediabetes and related conditions of the metabolic syndrome. It does not provide specific medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical or nutrition advice or delay in seeking it because of something you have read on this website.

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