Kombucha’s Side Effects: Is It Bad for You?

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

My video on kombucha was one of the first I ever did, even featured in my blog NutritionFacts.org: the first month, where I marveled at the fact that I had reached nearly 100,000 people. Now, I’m honored to say, we reach more like 100,000 a day.

In that first kombucha video, I profiled a report published in the Journal of Intensive Care Medicine of a case of kombucha tea toxicity. A young guy ending up in an acidotic coma, which concluded that “[w]hile Kombucha tea is considered a healthy elixir, the limited evidence currently available raises considerable concern that it may pose serious health risks. Consumption of this tea should be discouraged, as it may be associated with life-threatening lactic acidosis.” And this was just one of several case reports of serious, and sometimes fatal, liver dysfunction and lactic acidosis within close proximity of ingestion.

For example, two cases in Iowa of severe metabolic acidosis including one death: the triggering of a life-threatening autoimmune muscle disease requiring emergency surgery, probably related to kombucha; shaking, shortness of breath, and a movement disorder after consumption of tea and no other medications; xerostomia, dizziness, nausea, vomiting, headache, and neck pain, which recurred on reingestion of the tea. Then, another case of severe metabolic lactic acidosis and a case of hepatotoxicity—liver toxicity—that resolved after stopping kombucha.

Why these sporadic cases? Maybe some unusual toxins developed in a particular batch. I mean it is a fermented product; so, it’s possible it was just contaminated by some bad bug. Like the time people smeared kombucha on their skin because they were told it had magical healing power. What it instead had was anthrax growing in it. So, even though such reports were rare, ten years ago I concluded maybe we should stick to foods that haven’t put people in a coma. But look, everything in life is all about risks versus benefits. Maybe it’s worth it. After all, it’s reputed to cure cancer, eliminate wrinkles, and even restore gray hair to its original color, marketed by alternative and naturopathic healers throughout the United States.

Currently, kombucha is praised as “the ultimate health drink” or damned as “unsafe,” claimed to be a universal wonderful drug, known as a purifying potion. But is it a potion or poison?

Evidently, back in the 20s, 30s, and 40s, there were several medical studies conducted by recognized physicians confirming all sorts of beneficial effects. I couldn’t wait to read them. Okay, so, they cite Dufrense and Farnworth. Okay, there it is, same claim, citing Allen. Okay what’s Allen, 1998? Oh, you’ve got to be kidding me. You’re citing some rando kombucha website. And here it is, defunct since 2001, sourced citationless from stuff that was posted on some mailing list.

Finally, in 2003, a systematic review of the clinical evidence that was published, and the main result of this systematic review was “the total lack of efficacy data.” No clinical studies were found. We just have these cautionary tale case reports. So, on the basis of these data, it was concluded that the largely undetermined benefits do not outweigh the documented risks of kombucha. It can, therefore, not be recommended. Okay, but that was back in 2003. How about a 2019 systematic review of the empirical evidence of human health benefit?

The “nonhuman” subjects literature claims numerous health benefits of kombucha, meaning mice and rats, but what we need are human clinical trials. And still, not a single controlled human study. But they did find one uncontrolled study purporting to show a significant reduction in fasting and after-a-meal blood sugars among type 2 diabetics. Nonetheless, despite no controlled trials, significant commercial shelf space is now dedicated to kombucha products, and there is widespread belief that the products promote health. So, we’re left with this extreme disparity between science and belief, with little convincing clinical evidence, yet health claims that are as far-reaching as they are implausible, while the potential for harm seems considerable. In such extreme cases, healthcare professionals should discourage consumers from using (and paying for) anything that only seems to benefit those who sell it.

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Video production by Glass Entertainment

Motion graphics by Avocado Video

• beverages
• blood sugar
• diabetes
• fermented foods
• headaches
• kombucha tea
• liver disease
• liver health
• nausea
• pain
• tea