The Effect of Kombucha on Blood Sugar Levels in Humans

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

• Status: Completed
• Conditions: Glucose; Blood Sugar; High; Glucose Metabolism Disorders (Including Diabetes Mellitus)
• Intervention / Treatment: Dietary supplement: Commercial kombucha tea; Dietary supplement: Brewed kombucha tea; Other: Control: Tea; Other: Control: Water

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: Interventional
• Enrollment (Actual): 33
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Julie M Kapp, MPH, PhD; Phone Number: 5738843684; Email: kappj@health.missouri.edu

Study Locations

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

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 30 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

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

How is the study designed?

Design Details

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

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intervention group 1: commercial kombucha; 8oz	Dietary supplement: Commercial kombucha tea; Commercially-available kombucha tea.
Experimental: Intervention group 2: brewed kombucha; 8oz	Dietary supplement: Brewed kombucha tea; Kombucha tea brewed
Active Comparator: Control group 1: tea; 8oz	Other: Control: Tea; Tea brewed in our lab.
Placebo Comparator: Control group 2: water; 8oz	Other: Control: Water; Tap water

What is the study measuring?

Primary Outcome Measures

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

Secondary Outcome Measures

Outcome Measure	Time Frame
Blood pressure	Baseline

Collaborators and Investigators

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

Study record dates

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

• Keywords: tea; kombucha; kombucha tea; fermented food
• Additional Relevant MeSH Terms: Hyperglycemia; Metabolic Diseases; Glucose Metabolism Disorders
• Other Study ID Numbers: 2014707

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No