Using Gut Microbial Gbu Gene Testing to Estimate Host TMAO Production Capacity

January 8, 2026 updated by: National Taiwan University Hospital

Evaluation of Microbial-derived TMAO Production From Carnitine Intake by Testing Fecal Gbu Gene

The risk of cardiovascular diseases from red meat consumption varies among individuals due to variations in gut microbiota. L-carnitine in red meat can be converted to TMAO in the body by certain bacteria. Not everyone experiences a significant increase in TMAO levels after consuming carnitine. Gut microbiota differences are observed between high and low TMAO producers. The presence of the gbu gene in gut microbiota is linked to TMAO production. This clinical research aims to determine if the gbu gene can predict TMAO levels after dietary carnitine intake.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

The risk of developing cardiovascular diseases due to the consumption of red meat varies among individuals, and this may be attributed to differences in the composition and function of gut microbiota. Studies have found that red meat, rich in L-carnitine, may be metabolized by certain anaerobic bacteria in the intestines to produce trimethylamine N-oxide (TMAO) in the human body. Previous research utilizing the oral carnitine challenge test (OCCT) revealed that not everyone experiences a significant increase in blood TMAO levels after consuming carnitine. Moreover, individuals with high TMAO production and low TMAO production showed distinct differences in their gut microbiota.

Furthermore, we have discovered a significant correlation between the abundance of the gbu gene in gut microbiota and the production of TMAO in response to dietary carnitine intake. Therefore, through the design of clinical research, we aim to investigate and assess whether the abundance of the gbu gene in gut microbiota can predict the levels of TMAO produced in the human body under dietary carnitine intake.

Study Type

Interventional

Enrollment (Estimated)

230

Phase

  • 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 Locations

  • Taiwan
      • Taipei, Taiwan
        • National Taiwan University Hospital

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

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Adult with age between 18 to 70
  • Must be able to swallow tablets

Exclusion Criteria:

  • Antibiotics use within one month
  • L-carnitine supplement use within one month
  • Chronic diarrhea
  • Myasthenia gravis
  • Diabetes mellitus
  • Parathyroid disorders
  • Chronic kidney disease
  • Epilepsy
  • Severe anemia
  • Cardiovascular diseases.

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: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: L-Carnitine supplementation
Participants are required to take a capsule containing 500mg L-carnitine/day continuous for 7-10 days. During the intervention, participants are asked to collect urine sample and dietary record each day. Blood and fecal samples will be collected before and after the intervention. Each participant needs to complete a food frequency questionnaire.
Dietary supplement: L-carnitine
Participants are required to take a capsule containing 500mg L-carnitine/day continuous for 7-10 days.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Blood TMAO level measured by LC-MS/MS
Time Frame: up to 7-10 days
up to 7-10 days
Urine TMAO level measured by LC-MS/MS
Time Frame: up to 7-10 days
up to 7-10 days
Fecal gbuB gene abundance measured by qPCR
Time Frame: up to 7-10 days
up to 7-10 days

Secondary Outcome Measures

Outcome Measure
Time Frame
Carnitine intake measured by 24hr dietary record
Time Frame: up to 7-10 days
up to 7-10 days
Gut microbiome profiles measured by shotgun metagenome sequencing
Time Frame: up to 7-10 days
up to 7-10 days

Collaborators and Investigators

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

Sponsor

National Taiwan University Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. 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)

July 24, 2023

Primary Completion (Estimated)

April 25, 2026

Study Completion (Estimated)

July 30, 2026

Study Registration Dates

First Submitted

July 20, 2023

First Submitted That Met QC Criteria

July 31, 2023

First Posted (Actual)

August 8, 2023

Study Record Updates

Last Update Posted (Estimated)

January 12, 2026

Last Update Submitted That Met QC Criteria

January 8, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 202303144RINA

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

The data will be uploaded to be public when the research is published

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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