Drinking kombucha could lower diabetics’ blood glucose levels, experts reveal

01 Aug 2023 --- Daily kombucha consumption for four weeks demonstrated lower fasting blood glucose levels compared to the control group who drank a placebo beverage, making it a potential nutritional intervention for people with diabetes. 

“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,” says Chagai Mendelson, lead author of the study.

The fermented tea lowered blood sugar levels for 12 people with diabetes. However, the researchers note that a larger trial is needed to confirm the results of the US-based study published in Frontiers in Nutrition. 

Diabetes intervention
Dan Merenstein, co-author of the study and a professor of human sciences and family medicine at Georgetown University School of Medicine, US, says: “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.”

“A lot more research needs to be done but this is very promising. 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 major bacteria and yeasts are highly reproducible and likely to be functionally similar between brands and batches, says Hutkins.The two groups had either kombucha daily for four weeks and after two months of “washing out,” the groups swapped beverages, unknowingly of which drink they consumed at the time. 

After four weeks, lower average fasting blood glucose levels were observed when drinking kombucha, from 164 to 116 mg per dl. The recommended blood sugar levels before meals are 70 to 130 mg per dl. 

A recent Australian study found similar results – that kombucha reduced the glycemic index (GI) and insulin index when consumed with a high-GI meal. At the same time, sugar-free soda water and diet lemonade did not. The finding simplified that lowering blood glucose levels could reduce the risk of insulin resistance and diabetes.

Yeast and bacteria
While investigating the ingredients responsible for this effect, the researcher confirmed with RNA gene sequencing that the main components of the drink – of equal amounts – were lactic acid bacteria, acetic acid bacteria and Dekkera – a type of yeast from the fungus Brettanomyces.

“Different studies of different kombucha brands by different manufacturers reveal slightly different microbial mixtures and abundances,” says senior author Dr. Robert Hutkins, a food science and technology professor at the University of Nebraska-Lincoln, US.

“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,” adds Hutkins.

“An estimated 96 million Americans have pre-diabetes – and diabetes itself is the eighth leading cause of death in the US, as well as being a major risk factor for heart disease, stroke and kidney failure,” notes Mendelson. 

Diabetes is one of the leading causes of death and disability worldwide – half a billion people are currently living with the disease. By 2050, that number is expected to increase to 1.3 billion people, according to a recent study published in The Lancet.

Edited by Beatrice Wihlander