Plasma Trimethylamine N-oxide Elevation Induced by L-carnitine Supplementation and Insulin Resistance (MR)

September 29, 2025 updated by: Robert Olek, Poznan University of Physical Education

The Role of Gut Microbiota Metabolite, Trimethylamine N-oxide, in the Insulin Resistance Development

The primary aims of the current study:

  • using L-carnitine supplementation modulate the level of plasma trimethylamine N-oxide to assess its effect on circulating cytokines related to diabetes and metabolic syndrome;
  • using simulated night-shift work intervention as a stress factor, explore the effect of circulating metabolites on insulin sensitivity

The secondary aim is to evaluate the effect of carnitine supplementation on gut microbiome composition.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

Subjects will be randomly divided in two groups: supplemented by L-carnitine 2g/day for 12 weeks, and placebo group receiving leucine in identical gelatine capsules.

Subjects who successfully complete the protocol will be divided into four subgroups - two with a changed circadian cycle and two controls (supplemented and placebo). Subgroups with a changed daily cycle will be able to sleep between 8:00 and 17:00 for four consecutive days, while during the night they will stay active in the laboratory. The oral glucose tolerance test (OGTT) will be performed before and after the circadian cycle modification. Glucose levels will be monitored by FreeStyle Libre Sensor. Moreover, the activity of the participants will be monitored by wearable activity trackers.

Before supplementation, as well as before circadian cycle modification and after finishing the whole experimental procedure, fasting blood samples will be collected for determination of plasma trimethylamine N-oxide (TMAO), trimethylamine (TMA), carnitine (free and acyl derivatives), protein markers of diabetes and inflammation.

Moreover, the stool samples will be collected before and after 12 weeks of supplementation, to determine the composition of the gut microbiome. In addition diet of participants will be monitored.

Study Type

Interventional

Enrollment (Actual)

40

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

  • Poland
      • Poznan, Poland, 61-871
        • Akademia Wychowania Fizycznego

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

16 years to 26 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • healthy volunteers,
  • must be able to swallow tablets

Exclusion Criteria:

  • smokers,
  • cardiovascular disease
  • liver disease
  • kidney disease
  • gastrointestinal disorders (including stomach ulcers and erosions)
  • diabetes

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: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: carnitine
2 grams of L-carnitine per day for 12 weeks
Dietary supplement: L-carnitine
L-carnitine-L-tartrate
Behavioral: Change of the circadian cycle
Reducing sleep at night for four consecutive days (enabling sleep between 8:00 and 17:00)
Placebo Comparator: leucine
2 grams of L-leucine per day for 12 weeks
Behavioral: Change of the circadian cycle
Reducing sleep at night for four consecutive days (enabling sleep between 8:00 and 17:00)
Dietary supplement: L-leucine
L-leucine
Experimental: modified circadian cycle
no sleep at night for four consecutive days (enabling sleep between 8:00 and 17:00).
Dietary supplement: L-carnitine
L-carnitine-L-tartrate
Dietary supplement: L-leucine
L-leucine
Active Comparator: normal circadian cycle
sleep at night for four consecutive days
Dietary supplement: L-carnitine
L-carnitine-L-tartrate
Dietary supplement: L-leucine
L-leucine

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Circulating microbiome metabolites
Time Frame: 13 weeks
Determination of plasma trimethylamine and trimethylamine N-oxide using ultra performance liquid chromatography - tandem mass spectrometer (UPLC-MS/MS) method
13 weeks
Circulating carnitine metabolites
Time Frame: 13 weeks
Determination of plasma free, total, and acyl-L-carnitines using ultra performance liquid chromatography - tandem mass spectrometer (UPLC-MS/MS) method
13 weeks
Circulating diabetes biomarkers
Time Frame: 13 weeks
insulin, C-peptide, ghrelin, leptin, resistin using enzyme-linked immunosorbent assay
13 weeks
Circulating inflammatory biomarkers
Time Frame: 13 weeks
tumor necrosis factor, C-reactive protein using enzyme-linked immunosorbent assay
13 weeks
Oral Glucose Tolerance Test
Time Frame: 1 week
The subjects will consume 75 g of glucose solution drink within a 5-minute time frame. The glucose level will be continuously monitored with the FreeStyle Libre Sensor.
1 week

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
gut microbiome composition
Time Frame: 13 weeks
16 S rRNA sequencing will be used to analyze the gut microbiome in the stool samples
13 weeks

Collaborators and Investigators

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

Sponsor

Poznan University of Physical Education

Investigators

  • Principal Investigator: Robert Olek, PhD, Poznań University of Physical Education

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)

February 7, 2022

Primary Completion (Estimated)

May 31, 2026

Study Completion (Estimated)

May 31, 2027

Study Registration Dates

First Submitted

February 11, 2022

First Submitted That Met QC Criteria

February 11, 2022

First Posted (Actual)

February 22, 2022

Study Record Updates

Last Update Posted (Estimated)

October 3, 2025

Last Update Submitted That Met QC Criteria

September 29, 2025

Last Verified

September 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2020/39/O/NZ7/01790

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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