Health enthusiasts have been known to rave about supplementing their diet with low-calorie probiotics — AKA drinking kombucha. Now, researchers have shown that the fermented tea beverage can help those with type 2 diabetes by lowering fasting blood glucose levels.
The research, which involved a pilot 12-people feasibility trial and was conducted by researchers at Georgetown University's School of Health, the University of Nebraska-Lincoln, and MedStar Health, suggests the possibility of a dietary intervention that could lower blood sugar levels in people with diabetes.
Kombucha, which has undergone bacterial and yeast fermentation, is well-recognized for preventing and controlling conditions like high blood pressure. Anecdotal reports of increased immunity, more energy, decreased food cravings, and decreased inflammation have helped to increase its popularity, but there hasn't been any concrete evidence to support these claims.
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.- Dan Merenstein from Georgetown University
What did the results entail?
One set of participants in the crossover design ingested 8 ounces of kombucha or a placebo beverage daily for four weeks. After two months had passed to "wash out" the biological effects of the drinks, the kombucha, and placebo were switched between groups for a further four weeks of consumption.
After four weeks, kombucha seemed to reduce the typical fasting blood glucose levels from 164 to 116 milligrams per deciliter, although the difference with the placebo was not statistically significant. Blood sugar levels before meals should be between 70 to 130 milligrams per deciliter, according to American Diabetes Association.
The findings, published in Frontiers in Nutrition, also examined the kombucha's fermenting bacteria composition to see which components could be the most potent. Using RNA gene sequencing, they discovered that the beverage was mainly made up of lactic acid bacteria, acetic acid bacteria, and a kind of yeast called Dekkera, with each germ present in almost similar amounts.
According to senior author, Robert Hutkins of the University of Nebraska-Lincoln, investigations of various kombucha brands by various producers indicate varying microbial mixes and abundances.
On the other hand, the primary bacteria and yeasts are pretty repeatable and probably behave similarly across brands and batches, continued Hutkins, which encouraged the research.
"An estimated 96 million Americans have pre-diabetes — and diabetes itself is the eighth leading cause of death in the U.S. as well as being a major risk factor for heart disease, stroke and kidney failure," says lead author Chagai Mendelson.
Mendelson concludes, "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."
- Frontiers in Nutrition. Kombucha tea as an anti-hyperglycemic agent in humans with diabetes – a randomized controlled pilot investigation.
- University Health Center | by Nebraska Medicine. Kombucha: What is it, and what are its health benefits?