Can Drinking Kombucha Help with Blood Sugar Control?


Do you enjoy sipping the fermented beverage called kombucha?  Although you might appreciate the tangy flavor of kombucha, researchers at Georgetown University’s School of Health, the University of Nebraska-Lincoln, and MedStar Health recently looked at this tart beverage’s benefits for lowering blood sugar. The results might surprise you. They found that consistently sipping kombucha over 4 weeks triggers a significant drop in fasting blood glucose.

What Is Kombucha?

Kombucha traces its roots back to ancient China and didn’t make its mark in the U.S. until the 1990s. Manufacturers make kombucha by fermenting tea with bacteria and yeast. Because it’s fermented, kombucha contains probiotics, gut-friendly bacteria that scientists believe are beneficial to gut health.  The fermentation process also creates a small amount of alcohol. Despite its growing popularity fueled by claims of enhanced immunity, elevated energy levels, and reduced inflammation, tangible scientific evidence to support these benefits is scarce, but that doesn’t mean they’ don’t exist.

As Dr. Dan Merenstein, a study author and professor of Human Sciences in Georgetown’s School of Health, points out, “While some laboratory and rodent studies have shown promise, and a small study in individuals without diabetes revealed blood sugar reduction, this is the inaugural research examining kombucha’s effects in people with diabetes. The journey of research ahead is extensive, but these preliminary findings hold great promise.”

The Clinical Trial: Sipping Kombucha for Lower Blood Sugar

Merenstein points out the study’s strength is in its crossover design, where participants consumed either eight ounces of kombucha or a placebo beverage daily for four weeks. This was followed by a two-month “washout” period to negate any lingering effects before swapping the beverages between groups for another four weeks. The participants were unaware of which beverage they were consuming during each phase.

Remarkably, after four weeks, kombucha consumption was associated with a notable drop in average fasting blood glucose levels, from 164 to 116 milligrams per deciliter. In contrast, the placebo’s effect was not statistically significant. This shift aligned with the American Diabetes Association’s recommended range of blood sugar levels before meals, falling between 70 to 130 milligrams per deciliter.

Looking into the microbial orchestra of fermenting microorganisms in kombucha, the researchers pinpointed lactic acid bacteria, acetic acid bacteria, and the yeast Dekkera as the prominent players. RNA gene sequencing confirmed their presence in equal proportions, supporting their potential significance.

Dr. Robert Hutkins, the study’s senior author, adds, “Microbial compositions might vary slightly across different brands, yet the foundational bacteria and yeasts remain consistent, reflecting functional similarity across brands and batches.”

How Might Kombucha Lower Blood Glucose?

You might wonder how kombucha lowers blood glucose. Although scientists don’t know the exact mechanism, they have some theories. Research shows people with type 2 diabetes are more likely to have an unbalanced gut microbiome. Such an imbalance may contribute to blood sugar spikes.

Plus, people with type 2 diabetes are at higher risk of low-grade inflammation that contributes to insulin resistance and blood sugar spikes.  Kombucha contains probiotics that help boost gut microbiome diversity and antioxidants that help counter inflammation. Kombucha made with green tea contains green tea polyphenols that help fight inflammation. Studies show that when mice get green tea polyphenols, their fasting blood glucose levels dropped.

However, keep this in mind. These studies used animal models, so directly applying these findings to human biology isn’t a sure bet. The precise mechanisms that link kombucha or green tea polyphenols to blood glucose levels are intricate and still need unraveling.

Are There Downsides to Drinking Kombucha?

Despite its potential health benefits, there are some potential risks to drinking kombucha. Unless it’s made properly, kombucha can harbor harmful bacteria or mold. In fact, there are cases of people becoming ill from drinking kombucha that wasn’t made properly.  Still, as the Food and Drug Administration (FDA) points out, it’s a safe beverage if you buy it from a source that prepares it properly.

You can also make your own at home, but you’ll need to learn the proper procedure for making it safely and use the right containers. Cleanliness and attention to sterile procedures is a must if you make it at home. Otherwise, buy it from reputable sources. Always refrigerate kombucha at the appropriate temperature to keep the bacteria and yeast in the beverage inactive. Doing this will help maintain kombucha’s safety and preserve the quality of the beverage. Always check the expiration date before buying it too.


Kombucha won’t cure prediabetes or type 2 diabetes but sipping it could help you control your blood sugar, based on early research. With an estimated 96 million Americans teetering on the edge of pre-diabetes, and diabetes ranking as the eighth leading cause of death in the U.S., it’s a significant finding.

Chagai Mendelson, the lead author, underscores the urgency, “The promising evidence from this common beverage could shape diabetes management. As we move forward, a larger trial could build upon the lessons of this study to definitively explore kombucha’s potential to curtail blood glucose levels and address type-II diabetes.”

If you drink kombucha because you enjoy it or for its health benefits, buy it from a reputable source. Also, talk to your doctor before adding it to your diet. And be sure you adopt other lifestyle habits that will lower your risk of prediabetes and type 2 diabetes – exercise, an unprocessed diet, adequate sleep, stress management, and losing weight if you’re overweight. Also, keep tabs on your blood glucose, so you know where you stand.


  • 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 with diabetes – a randomized controlled pilot investigation. Frontiers in Nutrition, 2023; 10 DOI: 10.3389/fnut.2023.1190248.
  • Mayasari et al. “Glucose and Triglycerides Content of Duck Blood as The Effect of Kombucha Fermentation.” (2012).
  • Chen T, Liu AB, Sun S, Ajami NJ, Ross MC, Wang H, Zhang L, Reuhl K, Kobayashi K, Onishi JC, Zhao L, Yang CS. Green Tea Polyphenols Modify the Gut Microbiome in db/db Mice as Co-Abundance Groups Correlating with the Blood Glucose Lowering Effect. Mol Nutr Food Res. 2019 Apr;63(8):e1801064. doi: 10.1002/mnfr.201801064. Epub 2019 Jan 30. PMID: 30667580; PMCID: PMC6494111.
  • Murphy, Torie E. et al. “Safety Aspects and Guidance for Consumerson the Safe Preparation, Handling and Storage of Kombucha — A Fermented Tea Beverage.” Food protection trends 38 (2018): 329-337.
  • Massoud, R., Jafari-Dastjerdeh, R., Naghavi, N., KianoushKhosravi, -., & Darani (2021). All Aspects of Antioxidant Properties of Kombucha Drink. Biointerface Research in Applied Chemistry.

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