Drinking Kombucha Aids in Blood Sugar Regulation
- Kombucha is a tea fermented with bacteria and yeasts that has been consumed throughout history as early as 200 B.C.
- Kombucha is a popular drink in the U.S, U.K, Australia, and China, and commonly thought to support gut health.
- This was a small study, including only 12 participants with clinical blood sugar dysregulation.
- Participants consumed either kombucha or placebo daily for 4 weeks, and blood sugar levels were recorded at baseline, week 1, and week 4 (end) of study.
- Consumption of kombucha was associated with a measurable decline in average fasting blood glucose.
People with [blood sugar regulation disorders] who drank the fermented tea drink kombucha for four weeks had lower fasting blood glucose levels compared to when they consumed a similar-tasting placebo beverage, according to results from a clinical trial conducted by researchers at Georgetown University's School of Health, the University of Nebraska-Lincoln and MedStar Health. This finding, from a pilot 12-person feasibility trial, points to the potential for a dietary intervention that could help lower blood sugar levels in people with [blood sugar regulation disorders] and also establishes the basis for a larger trial to confirm and expand upon these results.
This finding was reported in Frontiers in Nutrition on August 1, 2023.
Kombucha is a tea fermented with bacteria and yeasts and was consumed as early as 200 B.C. in China, but it did not become popular in the U.S. until the 1990s. Its popularity has been bolstered by anecdotal claims of improved immunity and energy and reductions in food cravings and inflammation, but proof of these benefits has been limited.
"Some laboratory and rodent studies of kombucha have shown promise and one small study in people without [blood sugar regulation disorders] showed kombucha lowered blood sugar, but to our knowledge this is the first clinical trial examining effects of kombucha in people with [blood sugar regulation disorders]," says study author Dan Merenstein, M.D., professor of Human Sciences in Georgetown's School of Health and professor of family medicine at Georgetown University School of Medicine. "A lot more research needs to be done but this is very promising."
Merenstein continued, "A strength of our trial was that we didn't tell people what to eat because we used a crossover design that limited the effects of any variability in a person's diet."
The crossover design had one group of people drinking about eight ounces of kombucha or placebo beverage daily for four weeks and then after a two-month period to 'wash out' the biological effects of the beverages, the kombucha and placebo were swapped between groups with another four weeks of drinking the beverages. Neither group was told which drink they were receiving at the time.
Kombucha appeared to lower average fasting blood glucose levels after four weeks from 164 to 116 milligrams per deciliter while the difference after four weeks with the placebo was not statistically significant. Guidelines from the ADA recommended blood sugar levels before meals should be between 70 to 130 milligrams per deciliter.
The researchers also looked at the makeup of fermenting micro-organisms in kombucha to determine which ingredients might be the most active. They found that the beverage was mainly comprised of lactic acid bacteria, acetic acid bacteria, and a form of yeast called Dekkera, with each microbe present in about equal measure; the finding was confirmed with RNA gene sequencing.
The kombucha used in this study was produced by Craft Kombucha, a commercial manufacturer in the Washington, DC, area. It has been re-branded as Brindle Boxer Kombucha.
"Different studies of different brands of kombucha by different manufacturers reveal slightly different microbial mixtures and abundances," says Robert Hutkins, Ph.D., University of Nebraska-Lincoln and the study's senior author. "However, the major bacteria and yeasts are highly reproducible and likely to be functionally similar between brands and batches, which was reassuring for our trial."
"We were able to provide preliminary evidence that a common drink could have an effect on [blood sugar regulation disorders]. 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 [blood sugar regulation disorders]."
Additional study authors at Georgetown University are Sabrina Sparkes, a student in the School of Health, Varun Sharma and Sameer Desale. In addition to Hutkins, Chloe Christensen, Jennifer M. Auchtung, Car Reen Kok and Heather E. Hallen-Adams are at the University of Nebraska-Lincoln.
- Chagai Mendelson, Sabrina Sparkes, Daniel J. Merenstein, Chloe Christensen, Varun Sharma, Sameer Desale, Jennifer M. Auchtung, Car Reen Kok, Heather E. Hallen-Adams, Robert Hutkins. Kombucha tea as an anti-hyperglycemic agent in humans – a randomized controlled pilot investigation. Frontiers in Nutrition, 2023; 10 DOI: 10.3389/fnut.2023.1190248