Kombucha

Also called Kombucha tea, Fermented tea, SCOBY tea, Green tea kombucha, Black tea kombucha.

Best grade C across 8 graded outcomes Other Last checked

The short answer

From 17 sources

Human kombucha trials are few and small. A 12-person pilot linked 240 mL a day to lower fasting glucose in type 2 diabetes, and one meal test blunted the glucose rise. A 59-person Brazilian diet trial found no extra weight loss, and a 90-person runners' trial no antioxidant benefit. Case reports describe acidosis, liver injury and lead poisoning.

Every graded outcome on this page

8 rows · line = participants
  1. Grade CAntioxidant capacity and immune markers during running trainingOxidative stressn 63
  2. Grade CWeight and body fat on a calorie-restricted dietBody weightn 59
  3. Grade COxidative stress and endothelial markersOxidative stressn 59
  4. Grade CCholesterol and other cardiometabolic markersCholesteroln 59
  5. Grade DConstipation-predominant IBS in womenConstipationn 40
  6. Grade DGut microbes and inflammation in healthy adultsGut microbesn 24
  7. Grade DFasting blood glucose in type 2 diabetesBlood sugarn 12
  8. Grade DBlood glucose and insulin after a high-GI mealBlood sugarn 11
  9. 5 more graded outcomes, in the evidence chapter

Key facts

What it is
Tea and sugar fermented by yeasts and acetic and lactic acid bacteria; the drink in one trial held about 1.5% ethanol13
Blood sugar
Fasting glucose fell from 164 to 116 mg/dL over 4 weeks in a 12-person diabetes pilot; the placebo change was not significant3
Weight loss
200 mL a day added to a calorie-restricted diet gave no extra weight or fat loss over 10 weeks (59 adults)5
Alcohol
US rules classify kombucha that reaches 0.5% alcohol at any point, including after bottling, as an alcohol beverage1
Case reports
CDC investigated two severe illnesses, one fatal, in Iowa in 1995; later reports describe lactic acidosis, liver injury and lead poisoning from kombucha brewed in glazed ceramic pots210111314

What it is

Kombucha is sweetened tea fermented by a culture of yeasts and bacteria; it is sold as a drink, sometimes as a powder or capsule.

How it works

Proposed

Unproven in people. The drink contains live microbes, organic acids (lactic and acetic) and tea polyphenols; authors suggest these may slow glucose absorption or shift gut microbes, but the trials measured outcomes, not a pathway.348

Forms, side by side

2 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.

Kombucha forms compared

2 forms
Kombucha forms compared: 2 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
2 formsBrewed kombucha drink (black or green tea)With added fibre or vitamins
Absorption in peopleContains live microbes at about a million CFU per mL, lactic and acetic acids under 1%, and ethanol (1.5% in the 2023 pilot drink).3No absorption data; the added inulin is itself a fermentable fibre.9
GI toleranceNo serious adverse events were reported in the cited trials; rare case reports describe acidosis and liver injury.351011The 10-day IBS-C pilot abstract reports no tolerability problems.9
Studied forBlood sugar, body weight, gut microbesConstipation (IBS-C)
  1. Brewed kombucha drink (black or green tea)
    Absorption in people
    Contains live microbes at about a million CFU per mL, lactic and acetic acids under 1%, and ethanol (1.5% in the 2023 pilot drink).3
    GI tolerance
    No serious adverse events were reported in the cited trials; rare case reports describe acidosis and liver injury.351011
    Studied for
    Blood sugar, body weight, gut microbes
  2. Kombucha with added fibre or vitamins
    Absorption in people
    No absorption data; the added inulin is itself a fermentable fibre.9
    GI tolerance
    The 10-day IBS-C pilot abstract reports no tolerability problems.9
    Studied for
    Constipation (IBS-C)
Every cell holds data from a cited page; citation numbers link to the page that holds them.Scroll the table for every column

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

8 graded outcomes, largest study first

8 graded outcomes: 3 improved, 1 mixed, 4 no effect. The largest, a 2026 randomized trial of 63 people on antioxidant capacity and immune markers during running training, found no effect. Outcomes that improved came from smaller studies: a median of 12 people, against 59 for no effect.

5. Constipation-predominant IBS in women: improved, 40 people57. Fasting blood glucose in type 2 diabetes: improved, 12 people78. Blood glucose and insulin after a high-GI meal: improved, 11 people8
3. Oxidative stress and endothelial markers: mixed, 59 people3
1. Antioxidant capacity and immune markers during running training: no effect, 63 people12. Cholesterol and other cardiometabolic markers: no effect, 59 people24. Weight and body fat on a calorie-restricted diet: no effect, 59 people46. Gut microbes and inflammation in healthy adults: no effect, 24 people6

1Antioxidant capacity and immune markers during running training

No effect · Grade C · RCT, 63 people, 2026

Healthy beginner runners aged 18-45 in supervised training (Brazil)

Dose, result and source
Every graded outcome on this page, largest study first
OutcomeFoundPeopleStudyWho was studied
Antioxidant capacity and immune markers during running trainingNo effect63Grade C · RCT, 2026Healthy beginner runners aged 18-45 in supervised training (Brazil)
Cholesterol and other cardiometabolic markersNo effect59Grade C · RCT, 2026Brazilian adults with BMI above 27
Oxidative stress and endothelial markersMixed59Grade C · RCT, 2025Brazilian adults aged 18-45 with excess weight and no chronic disease
Weight and body fat on a calorie-restricted dietNo effect59Grade C · RCT, 2024Brazilian adults with excess body weight
Constipation-predominant IBS in womenImproved40Grade D · Pilot RCT, 2023Russian women with IBS-C
Gut microbes and inflammation in healthy adultsNo effect24Grade D · RCT, 2024Healthy US adults eating a Western diet (16 kombucha, 8 control)
Fasting blood glucose in type 2 diabetesImproved12Grade D · Crossover RCT, 2023US adults with type 2 diabetes at one urban hospital
Blood glucose and insulin after a high-GI mealImproved11Grade D · Crossover RCT, 2023Healthy Australian adults
Each circle is one graded outcome on this page, numbered from the largest study down, and placed by how many people it studied (log scale). It shows who was studied and what was found, not advice about your dose.

Every graded row

8 rows

Showing 8 of 8 outcomes. Human trials only.

Grade CAntioxidant capacity and immune markers during running trainingOxidative stressNo antioxidant benefitRCT
n 63 · 2026

No effect No change in the primary outcome, plasma antioxidant power (FRAP), or in immune and oxidative responses to a single exercise bout; neutrophils rose and lymphocytes fell with plain kombucha, findings the authors call exploratory after correction for multiple testing.

Design
RCT, n = 63, 2026
Population
Healthy beginner runners aged 18-45 in supervised training (Brazil)
Form
Green tea kombucha, with or without grape skin extract, vs no kombucha
Dose
200 mL a day
Duration
12 weeks
Source
Reference 17 · PubMed 42799570 (opens PubMed)
Grade CWeight and body fat on a calorie-restricted dietBody weightNo extra weight lossRCT
n 59 · 2024

No effect Both groups lost weight, BMI and body fat with no difference between groups. The kombucha group had a lower lipid accumulation product and did not show the IL-6 rise seen in controls.

Design
RCT, n = 59, 2024
Population
Brazilian adults with excess body weight
Form
Green tea kombucha plus diet vs diet alone
Dose
200 mL a day
Duration
10 weeks
Source
Reference 5 · PubMed 39339787 (opens PubMed)
Grade COxidative stress and endothelial markersOxidative stressOne marker lower, others unchangedRCT
n 59 · 2025

Mixed Hydrogen peroxide, a pro-oxidant marker, fell vs control (P = 0.007); every other oxidative stress and endothelial marker was unchanged.

Design
RCT, n = 59, 2025
Population
Brazilian adults aged 18-45 with excess weight and no chronic disease
Form
Green tea kombucha plus diet vs diet alone
Dose
200 mL a day
Duration
10 weeks
Source
Reference 6 · PubMed 40637142 (opens PubMed)
Grade CCholesterol and other cardiometabolic markersCholesterolNo between-group differenceRCT
n 59 · 2026

No effect Total cholesterol, LDL, triglycerides and uric acid fell from baseline in the kombucha group, but changes did not differ between groups for any marker; men on kombucha had lower HbA1c than control men (subgroup).

Design
RCT, n = 59, 2026
Population
Brazilian adults with BMI above 27
Form
Green tea kombucha plus diet vs diet alone
Dose
200 mL a day
Duration
10 weeks
Source
Reference 7 · PubMed 41957662 (opens PubMed)
Grade DConstipation-predominant IBS in womenConstipationMore frequent stools (fortified drink)Pilot RCT
n 40 · 2023

Improved Stool frequency rose from 0.60 to 0.85 a day on the enriched kombucha (P = 0.004) but not on water, and stool form and the feeling of incomplete emptying improved.

Design
Pilot RCT, n = 40, 2023
Population
Russian women with IBS-C
Form
Kombucha enriched with inulin (2.53 g) and B vitamins vs water
Dose
220 mL a day
Duration
10 days
Source
Reference 9 · PubMed 38149073 (opens PubMed)
Grade DGut microbes and inflammation in healthy adultsGut microbesModest microbiome shifts onlyRCT
n 24 · 2024

No effect No significant changes in blood chemistry or inflammation markers across the cohort; within the kombucha group fasting insulin and HOMA-IR rose from baseline, and some short-chain-fatty-acid-producing microbes increased.

Design
RCT, n = 24, 2024
Population
Healthy US adults eating a Western diet (16 kombucha, 8 control)
Form
Kombucha vs no kombucha
Dose
Daily kombucha (amount not given in the abstract)
Duration
4 weeks
Source
Reference 8 · PubMed 39738315 (opens PubMed)
Grade DFasting blood glucose in type 2 diabetesBlood sugarLower fasting glucose (pilot)Crossover RCT
n 12 · 2023

Improved Average fasting glucose fell from 164 to 116 mg/dL at 4 weeks on kombucha (p = 0.035); on placebo it went from 162 to 141 mg/dL (p = 0.078). Glucose was self-measured, and the abstract compares each arm with its own baseline.

Design
Crossover RCT, n = 12, 2023
Population
US adults with type 2 diabetes at one urban hospital
Form
Kombucha drink vs placebo drink
Dose
240 mL a day
Duration
4 weeks per arm, 8-week washout
Source
Reference 3 · PubMed 37588049 (opens PubMed)
Grade DBlood glucose and insulin after a high-GI mealBlood sugarSmaller post-meal glucose riseCrossover RCT
n 11 · 2023

Improved Meal glycemic index was 68 with kombucha vs 86 with soda water (p = 0.041), and the insulin index 70 vs 85; diet soft drink made no difference.

Design
Crossover RCT, n = 11, 2023
Population
Healthy Australian adults
Form
Unpasteurised kombucha vs soda water vs diet soft drink with a standard meal
Dose
One serving with a single meal
Duration
Single test sessions
Source
Reference 4 · PubMed 36875857 (opens PubMed)

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

Three papers, one trial

The weight, oxidative stress and cholesterol reports all come from the same 59 Brazilian adults, so they are not independent confirmations.567

How we got this: Identical design, group sizes and author team across the 2024-2026 reports

Blood sugar data are tiny

The two positive glucose studies enrolled 12 and 11 people; the 2024 healthy-adult trial saw fasting insulin rise rather than fall.348

How we got this: Participant counts and results of the cited trials

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from a single serving with one meal to 200-240 mL of kombucha a day for up to 12 weeks.345917

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

What Kombucha meets

1 cited row 2 tested together

Medicines 1

Kombucha1 medicine · 2 supplements

Supplements and foods 2

  • Reference summary
  • Tested together in a graded trial
Also cited: 2 tested together

  1. Drugs whose absorption depends on stomach acid

    • ReviewReference summary

      Drugs whose absorption depends on stomach acid: Kombucha is acidic and may change how well such drugs dissolve and are absorbed; MSKCC lists this as a herb-drug interaction and advises people on drugs sensitive to stomach pH not to take kombucha.

      Source 12, Memorial Sloan Kettering Cancer Center (2021)

  2. InulinInulin page

    • Tested together

      Constipation-predominant IBS in women. Graded on the Kombucha page; tested together is not a claim that they work better together.

  3. Vitamin B complexVitamin B complex page

    • Tested together

      Constipation-predominant IBS in women. Graded on the Kombucha page; tested together is not a claim that they work better together.

Rows as our evidence profiles cite them; links stay on this site. Line weight shows what backs a row, not how serious an interaction is. No line means none was found in our sources, not that a combination is safe. Not medical advice: ask your pharmacist.

Interactions

1 agent
Published interactions, grouped by kind
AgentWhat the source saysEvidence
Medicines1
Drugs whose absorption depends on stomach acidKombucha is acidic and may change how well such drugs dissolve and are absorbed; MSKCC lists this as a herb-drug interaction and advises people on drugs sensitive to stomach pH not to take kombucha.12Review

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Kombucha and your picks, and between your picks.

Most cited:

Add a supplement or medicine you take to check it against Kombucha.

Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Not medical advice, and no dosing advice. An empty result means no row we cite names that pair, by name or through a drug class we can link the medicine to, not that a combination is safe. Where our sources name only a group of medicines we cannot match, the cabinet says so. Ask your pharmacist before you combine supplements and medicines.

Who should be careful

5 groups
People avoiding alcohol
Kombucha can keep fermenting in the bottle; US rules classify any kombucha that reaches 0.5% alcohol by volume as an alcohol beverage, and the 2023 trial drink held 1.5% ethanol.13
Pregnancy and breastfeeding
MotherToBaby advises skipping kombucha during pregnancy: it contains some alcohol (home brews can reach 3% or more), raw or home-brewed versions can carry foodborne bacteria such as Listeria and Salmonella, and it contains caffeine. An occasional 'alcohol-free' kombucha while breastfeeding is unlikely to affect the infant.16
Home brewing
Home brews are easy to contaminate. Kombucha grown in unhygienic conditions and applied to the skin was linked to cutaneous anthrax in Iran, and the tea's acids leached lead from glazed ceramic vessels: an Australian couple needed chelation after six months of drinking it, and a ready-to-drink batch in a Spanish family outbreak held 47 mg/kg of lead. Do not brew or store kombucha in glazed ceramic.12151314
Weakened immunity
MSKCC advises that people with a suppressed immune system not drink kombucha made in an uncontrolled environment, as contamination with the mould Aspergillus has been reported. In one case report, a 22-year-old newly diagnosed with HIV developed lactic acidosis, high fever and kidney failure within 15 hours of drinking kombucha.1210
Liver problems
Case reports describe liver injury linked to kombucha tea, and CDC investigated two severe illnesses (one death) in Iowa in 1995 without proving the tea was the cause.211
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.

How to read the label

What to check on the Supplement Facts panel.

How to read the label

3 checks
Check the alcohol line

Drinks sold as non-alcoholic must stay under 0.5% alcohol after bottling; continued fermentation can push them over.1

Trial drinks were unpasteurised

The glucose studies used live, unpasteurised kombucha; pasteurised or powdered products were not tested.34

Brewing at home

Use food-safe vessels: lead poisoning cases came from kombucha brewed or sold in glazed ceramic containers.1314

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

7 answers
Does kombucha lower blood sugar?

Possibly, but the data are tiny. In a 12-person pilot, fasting glucose fell from 164 to 116 mg/dL over 4 weeks of kombucha, and in 11 healthy adults kombucha lowered a meal's glycemic index from 86 to 68.34

Does kombucha help with weight loss?

Not in the one trial that tested it. Adding 200 mL a day of green tea kombucha to a calorie-restricted diet gave no extra weight or fat loss over 10 weeks.5

Is kombucha good for gut health?

Evidence is thin. A 4-week trial in 24 healthy adults found only modest microbiome changes, and the IBS-C benefit came from a drink with added inulin fibre.89

Does kombucha help athletes or exercise recovery?

Not in the one trial that tested it. In 90 beginner runners, 200 mL a day of green tea kombucha for 12 weeks did not change plasma antioxidant power or immune responses to exercise; a few blood-cell shifts were judged exploratory.17

Does kombucha contain alcohol?

Usually a little. Fermentation makes ethanol, the 2023 trial drink held 1.5%, and US rules count kombucha at 0.5% or more alcohol as an alcohol beverage.13

Is pasteurised or home-brewed kombucha better?

The blood sugar studies used freshly brewed kombucha, one described as live and unpasteurised; pasteurised or powdered products were not tested for those effects. Home brews carry more risk: contamination and lead poisoning from glazed ceramic pots have been reported.341315

Is kombucha safe?

Usually for healthy adults drinking commercial kombucha, but not risk-free. Case reports link it to lactic acidosis and liver injury, home brews have been contaminated, and kombucha brewed in glazed ceramic pots has caused lead poisoning. MotherToBaby advises avoiding it in pregnancy.210111316

Sources

17 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

17 sources
  1. 1Kombucha (TTB G 2010-3A, last updated August 13, 2019)Guideline Alcohol and Tobacco Tax and Trade Bureau (TTB), 2019 · ttb.gov
  2. 2Unexplained severe illness possibly associated with consumption of Kombucha tea--Iowa, 1995.Safety communication MMWR Morb Mortal Wkly Rep, 1995 · PMID 7476846
  3. 3Kombucha tea as an anti-hyperglycemic agent in humans with diabetes - a randomized controlled pilot investigation.Crossover RCT Front Nutr, 2023 · PMID 37588049
  4. 4Glycemic index and insulin index after a standard carbohydrate meal consumed with live kombucha: A randomised, placebo-controlled, crossover trial.Crossover RCT Front Nutr, 2023 · PMID 36875857
  5. 5Green Tea Kombucha Impacts Inflammation and Salivary Microbiota in Individuals with Excess Body Weight: A Randomized Controlled Trial.RCT Nutrients, 2024 · PMID 39339787
  6. 6Effect of regular green tea (Camellia sinensis) kombucha consumption on oxidative stress and endothelial health in individuals with excess body weight: a randomized controlled trial.RCT Br J Nutr, 2025 · PMID 40637142
  7. 7Effect of Green Tea Kombucha Within an Energy-Restricted Diet on Cardiometabolic Risk Markers in Individuals With Excess Body Weight: A Randomized Controlled Trial.RCT J Food Sci, 2026 · PMID 41957662
  8. 8Modulating the human gut microbiome and health markers through kombucha consumption: a controlled clinical study.RCT Sci Rep, 2024 · PMID 39738315
  9. 9Evaluation of the Efficacy of Kombucha-Based Drink Enriched with Inulin and Vitamins for the Management of Constipation-Predominant Irritable Bowel Syndrome in Females: A Randomized Pilot Study.Pilot RCT Curr Dev Nutr, 2023 · PMID 38149073
  10. 10A case of Kombucha tea toxicity.Observational J Intensive Care Med, 2009 · PMID 19460826
  11. 11A Case of Hepatotoxicity Related to Kombucha Tea Consumption.Observational S D Med, 2016 · PMID 26882579
  12. 12Kombucha (About Herbs, last updated June 10, 2021)Database Memorial Sloan Kettering Cancer Center, 2021 · mskcc.org
  13. 13Lead poisoning from drinking Kombucha tea brewed in a ceramic pot.Observational Med J Aust, 1998 · PMID 9887919
  14. 14[Brote familiar de saturnismo asociado al consumo de kombucha fabricada y comercializada en envases cerámicos.].Observational Rev Esp Salud Publica, 2023 · PMID 37226984
  15. 15Cutaneous anthrax associated with the Kombucha "mushroom" in Iran.Observational JAMA, 1998 · PMID 9820255
  16. 16Kombucha and Pregnancy: Answers to Your Brewing QuestionsFact sheet MotherToBaby (Organization of Teratology Information Specialists), 2020 · mothertobaby.org
  17. 17Acute and Chronic Effects of Green Tea Kombucha With and Without Grape Skin Extract on Immune and Oxidative Stress Markers in Beginner Runners: A Randomized Controlled Trial.RCT J Food Sci, 2026 · PMID 42799570

What changed

Every dated change to this page: what changed, who made it and why.

Change log

3 entries
Dated changes to this page
DateChangeWho and why
summary, evidence, studied doses, interactions, FAQ, questions, relatedAdded a 2026 randomized trial in 90 beginner runners (200 mL a day of green tea kombucha for 12 weeks: no change in plasma antioxidant power, grade C) and the stomach-acidity drug interaction listed by MSKCC. Studied doses extended to 12 weeks; summary trimmed to 60 words; FAQ items on exercise and on pasteurised vs home-brewed drinks; page questions and goal-hub links. Checked: no LactMed or LiverTox entry for kombucha and no NCCIH or MedlinePlus kombucha page. Not added: a 2026 uncontrolled pre-post study of black tea kombucha in 36 adults (41870392, no control group) and a 2023 systematic review mixing animal and human studies (34698580).Writer: Kymata Health EditorialTrigger: A–Z audit against docs/supplements/AUDIT-STANDARD.md
allInitial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title, year, journal) and each cited abstract read; numbers taken from the abstracts. Funding and ties disclosed per study: Synbiotic Health (2023 pilot), a Good Brew Company consultant (2023 meal test), GT's Living Foods funding (2024 microbiome trial), none declared for the Brazilian trial. The three Brazilian reports are flagged as one trial. Safety rows use TTB, CDC MMWR and published case reports only. Where to buy: we didn’t list a product; none of the stores we checked sells kombucha.Writer: Kymata Health EditorialTrigger: new page
who should avoidSafety review: added pregnancy and breastfeeding (MotherToBaby), home-brew contamination including cutaneous anthrax (JAMA 1998), lead poisoning from glazed ceramic vessels (Med J Aust 1998; Rev Esp Salud Publica 2023), and MSKCC's caution for people with suppressed immunity. PMIDs checked against NCBI esummary.Writer: Kymata Health EditorialTrigger: safety review

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