The Effect of Kombucha on Blood Sugar Levels in Humans

September 6, 2023 updated by: Julie Kapp, University of Missouri-Columbia

A Clinical Trial to Measure the Biochemical Response of Kombucha Tea in Humans

As a phase 0 clinical trial, we will learn how kombucha influences glucose metabolism in humans.

Study Overview

Detailed Description

Consumption of kombucha, a fermented tea beverage, has been promoted for a wide range of health benefits. However, a systematic literature review (Kapp & Sumner, 2019) revealed a lack of evidence for human health benefit. Despite the lack of evidence, U.S. retail sales of kombucha and other fermented beverages have increased 37.4% in 2017, and kombucha is the fastest growing product in the functional beverage market.

As a phase 0 clinical trial, we will learn how kombucha influences glucose metabolism in humans. We plan for 20 subjects to take part in this study.

This is a randomized-controlled counter-balanced study design. Subjects will be asked to complete 4 in-person visits over 2 months time (twice per month). At the first visit, subjects will be randomized into one of four groups. At each subsequent visit, subjects will be randomized into one of the remaining groups until they have completed each arm.

Arms (at least 5 subjects in each arm, minimum total=20 subjects)

  1. Intervention group 1: commercial kombucha: drink 8oz kombucha
  2. Intervention group 2: brewed kombucha: drink 8oz kombucha
  3. Control group: drink 8oz tea (the same type as used to brew the kombucha)
  4. Control group 2: drink 8oz tap water

Study Type


Enrollment (Actual)



  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

    • Missouri
      • Columbia, Missouri, United States, 65212
        • University of Missouri

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

30 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers



Inclusion Criteria:

  • Men or women ages 30-65 years old
  • English-speaking
  • Have transportation to campus
  • Overweight (BMI >= 25 kg/m2) or obese (BMI >=30 kg/m2)

Exclusion Criteria:

  • Currently use any type of nicotine product
  • A diagnosis of any of the following:

    • Diabetes (type 1 or 2)
    • Cancer
    • COPD
    • Chronic alcoholism
    • Peripheral vascular disease
    • Autoimmune disease
    • Chronic kidney disease
  • Pregnant or breastfeeding
  • Prescribed medication for insulin, glucose-lowering drugs, or steroids, such as prednisone
  • Have routinely taken prebiotic or probiotic supplements in the past 3 months
  • Have routinely consumed any of the following more than one time per week in the past month: kombucha, kefir, yogurt, kimchi, cottage cheese, raw apple cider vinegar (with the "mother"), sauerkraut, kvass.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Intervention group 1: commercial kombucha
Commercially-available kombucha tea.
Experimental: Intervention group 2: brewed kombucha
Kombucha tea brewed
Active Comparator: Control group 1: tea
Tea brewed in our lab.
Placebo Comparator: Control group 2: water
Tap water

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Fasting blood glucose level
Time Frame: Baseline
Blood drawn following a 10-12 hour fast.
Fasting insulin level.
Time Frame: Baseline
Blood drawn following a 10-12 hour fast.
Blood glucose level
Time Frame: 3 hour
Oral glucose tolerance test
3 hour
Insulin level
Time Frame: 3 hour
Oral glucose tolerance test
3 hour

Secondary Outcome Measures

Outcome Measure
Time Frame
Blood pressure
Time Frame: Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.


  • Principal Investigator: Julie M Kapp, MPH, PhD, University of Missouri-Columbia

Study record dates

These dates track the progress of study record and summary results submissions to Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 3, 2019

Primary Completion (Actual)

September 30, 2022

Study Completion (Actual)

September 30, 2022

Study Registration Dates

First Submitted

August 7, 2019

First Submitted That Met QC Criteria

August 7, 2019

First Posted (Actual)

August 9, 2019

Study Record Updates

Last Update Posted (Actual)

September 8, 2023

Last Update Submitted That Met QC Criteria

September 6, 2023

Last Verified

September 1, 2023

More Information

Terms related to this study

Other Study ID Numbers

  • 2014707

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product


Studies a U.S. FDA-regulated device product


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Clinical Trials on Glucose