Kombucha is a tart fermented tea that contains live cultures and some caffeine. Big claims are made for it, but studies in people are very few, so we make no health claims. Here is what the research does and does not show, and what to watch for.
What the research says
- The human evidence is very thin. A 2019 systematic review searched for research on kombucha in people. Of 310 articles it reviewed, it found one study in human subjects, and no trials under way in the registers it checked. The claims of benefit came from lab and animal studies, which the authors said need testing in clinical trials.
- A few small trials have followed. A 2023 pilot trial gave kombucha or a placebo drink to 12 adults for four weeks and measured blood sugar. With so few people it cannot show whether kombucha has any benefit, and its authors called for larger studies.
- Lab results are not results in people. Reviews describe many compounds from the tea and the culture, some with antioxidant activity in the lab. They also point to many unknowns, because teas, cultures and brewing methods differ so much between batches.
What is in your glass
- Caffeine from the tea. It varies widely: in one analysis of nine commercial kombuchas it ranged from about 15 to 113 milligrams per litre, and the highest one had caffeine added.
- Sugar that the microbes have not eaten. A longer brew leaves less. Amounts differ a lot from product to product, so check the label of any bottle you buy.
- Acid. Kombucha is acidic. The nine products in that analysis had similar acidity.
- Live bacteria and yeasts, if the kombucha is not pasteurised after fermenting.
Cautions
- Caffeine. If you avoid caffeine, do not drink it.
- Your teeth. In a 2023 lab study, all 13 drinks tested were acidic (pH 2.7 to 4.2). When four of them were tried on extracted teeth, the kombucha softened enamel more than flavoured sparkling water, and less than an energy drink. Drink kombucha with a meal rather than sipping it all day, and rinse your mouth with water afterwards.
- How much. Start with a small glass. Cleveland Clinic points to about 120ml (4 oz) a day as an amount that may not cause problems in healthy adults.
- Home brewing needs care. Use a glass jar, never clay or glazed earthenware, which can leach lead. Keep everything clean, check the acidity, and throw the batch away if you see fuzzy mould or smell something like nail polish. Our kombucha guide has the full method.
- Bottles build pressure. Open them slowly over the sink, and keep finished kombucha in the fridge.
So is kombucha worth drinking?
If you like the taste, yes: as a refreshing, tangy treat, not as medicine. For advice about your own health, ask your doctor.
You can try it ready-made with Kombucha Tea, or brew your own from a Kombucha SCOBY.
Sources: Kapp and Sumner 2019, Annals of Epidemiology, Kombucha: a systematic review of the empirical evidence of human health benefit; Mendelson et al. 2023, Frontiers in Nutrition, a randomized pilot investigation of kombucha in adults with type 2 diabetes; Antolak et al. 2021, Antioxidants, Kombucha tea: a double power of bioactive compounds from tea and a symbiotic culture of bacteria and yeasts; Yang et al. 2022, Microbial and chemical profiles of commercial kombucha products; Pierce et al. 2023, General Dentistry, Millennial drinks: acidity, fluoride content, and enamel softening; Cleveland Clinic, Kombucha. All opened 10 October 2026. Written by KefirBuy.
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