Kombucha: three small trials, no health effect that held up

Kombucha has been tested in people only a few times, and the results are mostly blank. In a randomized trial in 59 adults with excess weight, all on a 500 calories a day deficit diet, adding 6.8 fl oz (200 mL) of green tea kombucha daily for 10 weeks made no difference against diet alone for cholesterol, blood sugar markers or uric acid. The falls in LDL and triglycerides quoted from that trial happened within the kombucha group and did not beat the control group. In 24 healthy adults on a low-fiber Western diet, a 16 oz bottle a day for 4 weeks changed no blood or inflammation marker across the group and shifted gut bacteria modestly. Both trials were open label and small. This is the evidence as it stands, and it gives no reason to drink kombucha for your metabolism.

How much is actually in it

• Lab analysis of 38 foods and drinks found kombucha, like vinegar, supplies more than 1,000 mg of acetate per serve. — 38 commonly consumed foods and beverages analyzed by gas chromatography Evidence D source
  Acetate above 1000 mg per serve in kombucha and vinegar

What a real portion looks like

• US survey data weigh a standard 12 fl oz can or bottle of kombucha at 372 g, and 1 fl oz at 31 g. — — Evidence E source
  1 can or bottle (12 fl oz) = 372 g; 1 fl oz = 31 g; quantity not specified = 372 g
• A fermented-food questionnaire validated in 167 adults counts one portion of kombucha as 6 ounces, or 175 g. — 167 adults aged 18 to 60 from English-speaking countries (n = 167) Evidence C source
  Kombucha portion 6.2 oz (175 g); kombucha among the most frequently consumed fermented foods

What cooking and storage change

• Storing kombucha in a lead-glazed earthenware jug caused lead poisoning in one adult, since the acidic drink leaches lead. — two adults with lead poisoning in France, one traced to kombucha stored in a lead-glazed jug (n = 2) Evidence D source
  Lead poisoning presenting as abdominal pain or anemia

What it does to your health

• In 59 adults with excess weight on a 500 calories/day deficit diet, adding 6.8 fl oz (200 mL) of green tea kombucha daily for 10 weeks made no difference versus diet alone for any cardiometabolic marker. — adults aged 18 to 45 with BMI 27 or higher, Brazil, energy-restricted diet with or without 200 mL/day green tea kombucha for 10 weeks (n = 59) Evidence B source
  No between-group differences in change for lipids, glucose markers or uric acid (p > 0.05); within-group falls in LDL-c and triglycerides in the kombucha arm only
• In 24 healthy adults on a Western diet, a 16 oz bottle of kombucha a day for 4 weeks did not change blood markers or inflammation across the cohort and shifted gut bacteria only modestly. — healthy adults, San Diego, low-fiber Western diet, 16 kombucha vs 8 controls analyzed, one 16 oz commercial bottle daily for 4 weeks (n = 24) Evidence B source
  No significant change in biochemical or inflammatory markers; within-group rise in fasting insulin and HOMA-IR with kombucha; more Weizmannia in stool

Safety, limits and interactions

• A 2016 case report of hepatitis after kombucha notes that a few case reports raise concern about serious adverse effects. — one middle-aged woman with liver injury after kombucha tea (n = 1) Evidence D source
  Hepatotoxicity attributed to kombucha; no dose data in abstract

Who this works differently for

• In 40 people with constipation-type IBS, 7.4 fl oz (220 mL) a day of a pasteurized kombucha drink with added inulin raised stool frequency from 0.60 to 0.85 per day over 10 days. — adults with constipation-predominant IBS (Rome IV), 220 mL/day non-alcoholic pasteurized kombucha enriched with inulin 1.15 g/100 mL vs water, 10 days (n = 40) Evidence B source
  Stool frequency 0.60 to 0.85/day (p=0.004) vs no change with water; Bristol score 3.0 to 4.4

The bottom line

The one positive trial used a changed product. In 40 adults with constipation-type IBS, 7.4 fl oz (220 mL) a day of a pasteurized kombucha drink with added inulin fiber raised stool frequency from 0.60 to 0.85 a day over 10 days, while water changed nothing. Because fiber was added, that result cannot be credited to kombucha itself. In the healthy volunteer trial, fasting insulin rose within the kombucha group, an exploratory finding in 16 drinkers. A lab analysis of 38 foods found it supplies more than 1,000 mg of acetate per serve, like vinegar, from few kombucha samples. A bottle in US survey data is 12 fl oz, 372 g, though many sold are 16 oz. That acidity is behind the one clear safety point. In France an adult got lead poisoning from kombucha stored in a lead-glazed earthenware jug, a hazard of the container. A 2016 report of liver injury in one woman adds to a few case reports of serious reactions, with causality not established. We found no evidence on kombucha in pregnancy, in children or with medicines, and no data on its alcohol content made it into this page.

Sources

1. kmbc-r4-04 · food analysis
   Acetate is the most abundant SCFA detected, with kombucha and vinegar found to provide >1000 mg of acetate per serve.
   Mol Nutr Food Res, 2021 · checked 2026-09-29
2. kmbc-r4-08 · food portion data
   FNDDS 92306920 Tea, kombucha (fdc 2710509) | 1 can or bottle (12 fl oz) | 372 g || 1 fl oz (no ice) | 31 g || Quantity not specified | 372 g
   FNDDS 2021-2023, USDA, code 92306920 (Tea, kombucha) · checked 2026-09-29
3. kmbc-r4-09 · validation study
   As most fermented foods do not have established serving sizes, portion sizes were based on servings reported by Wastyk et al. [27], in which 6 ounces/175 g constituted one portion of kombucha, yoghurt, kefir and buttermilk and 0.25 cup/40 g for fermented vegetables.
   J Hum Nutr Diet, 2026 · checked 2026-09-29
4. kmbc-r4-06 · case report
   In both cases, the environmental investigation evidenced one main source of lead exposure, namely a lead-glazed earthenware jug in which a drink was stored, "kefir" in the first case, and "kombucha" tea in the second one.
   Rev Med Interne, 2009 · checked 2026-09-29
5. kmbc-r4-01 · randomized controlled trial
   However, in the total sample (Δ = final - initial), no significant differences were found between the control and kombucha groups (p > 0.05) for any evaluated marker.
   J Food Sci, 2026 · checked 2026-09-29
6. kmbc-r4-02 · randomized controlled trial
   We did not observe significant changes in either biochemical parameters or levels of circulating markers of inflammation across the entire cohort.
   Sci Rep, 2024 · checked 2026-09-29
7. kmbc-r4-05 · case report
   There is concern, however, from the evidence of a few case reports currently available, that it may pose life-threatening and/or adverse effects for users.
   S D Med, 2016 · checked 2026-09-29
8. kmbc-r4-03 · randomized controlled trial
   Significant increase of stool frequency was found at the EOT compared to BL in KG (n=20), Mean±SD: 0.60±0.31 to 0.85±0.19 times/day; p=0.004, while there was no change in CG (n=20): 0.63±0.33 vs 0.72±0.28, p=0.6.
   Vopr Pitan, 2022 · checked 2026-09-29