Dietary changes to reduce gut bacteria's impact on heart health

Gut Flora Metabolite Reduction After Dietary Intervention (GRADY)

Not applicable Interventional The Cleveland Clinic · NCT02016430

This study is testing whether changing what people eat can lower a harmful compound linked to heart problems, specifically in those with high levels of it.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment170 (estimated)
Ages18 Years and up
SexAll
SponsorThe Cleveland Clinic Academic / other
Locations1 site (Cleveland, Ohio)
Trial IDNCT02016430 on ClinicalTrials.gov

What this trial studies

This pilot study explores how dietary interventions can influence the production of trimethylamine-N-oxide (TMAO), a compound linked to cardiovascular risk, by gut flora. Participants with elevated TMAO levels will undergo tailored dietary modifications to assess their effectiveness in reducing TMAO generation. The study will measure TMAO levels using stable-isotope-labelled nutrients and compare results between individuals with high and normal TMAO levels. The goal is to better understand the relationship between diet, gut bacteria, and cardiovascular health.

Who should consider this trial

Good fit: Ideal candidates include adults aged 18 and older with elevated TMAO levels or specific kidney function criteria.

Not a fit: Patients with normal TMAO levels or those unable to comply with dietary modifications may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to dietary strategies that significantly lower cardiovascular risk by managing gut flora metabolism.

How similar studies have performed: Previous studies have indicated a potential link between diet and TMAO levels, suggesting this approach may yield beneficial results.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

Cohort 1 Inclusion criteria:

* Men and women age 18 years or above.
* Elevated TMAO metabolizers (\>5 µM) based on screening test and/or eGFR \< 60 at most recent measurement.
* Willing to remain on aspirin or able to be off aspirin or aspirin products for 1 week prior to starting the study and staying on the same aspirin regimen during the duration of the study.
* Willing to sign the consent form and follow the study protocol, which includes a 12-week dietary modification.

Cohort 2 Inclusion criteria:

* Men and women age 18 years or above.
* Willing to remain on aspirin or able to be off aspirin or aspirin products for 1 week prior to starting the study and staying on the same aspirin regimen during the duration of the study.
* Willing to sign the consent form and follow the study protocol.
* eGFR values ranging from 16-59

Cohort 3 Inclusion criteria:

* Men and women age 18 years or above.
* Willing to remain on aspirin or able to be off aspirin or aspirin products for 1 week prior to starting the study and staying on the same aspirin regimen during the duration of the study.
* Willing to sign the consent form and follow the study protocol.

Exclusion Criteria (all cohorts):

* Significant chronic illness or end-organ dysfunction, including known history of uncompensated heart failure, renal failure, pulmonary disease, hematologic diseases.
* Active infection or received antibiotics within 2 months of study enrollment
* Use of over-the-counter probiotic within past month, or ingestion of yogurt within past 7 days
* Having undergone bariatric procedures or surgeries such as gastric banding or bypass.
* Pregnancy.
* Any condition which, in the judgment of the Investigator, would place a patient at undue risk by being enrolled in the trial, or cause inability to comply with the trial

Where this trial is running

Cleveland, Ohio

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Dietary ModificationCardiovascular Risk FactorTMAOGut FloraDietary InterventionCholineCarnitine
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.