Gut Flora Metabolite Reduction After Dietary Intervention (GRADY)

  • End date
    Dec 19, 2022
  • participants needed
  • sponsor
    The Cleveland Clinic
Updated on 19 November 2021
trimethylamine n-oxide


Our group has recently identified the association between gut-flora-mediated carnitine and phosphatidylcholine metabolism, specifically trimethylamine-N-oxide (TMAO), and cardiovascular risk. This study investigates the ability for dietary intervention to modulate TMAO levels.


This is a pilot human study to characterize the relationship between gut flora-associated TMAO generation and dietary intervention. The investigators hypothesize that tailored dietary interventions may help to reduce the ability for gut flora to generate TMAO in individuals with elevated TMAO levels. Specific aims include:

  1. To investigate the proportion of subjects with persistently elevated circulating TMAO levels.
  2. To compare the amount of TMAO generated from gut flora using stable-isotope-labelled choline, carnitine, and betaine in subjects with elevated versus normal circulating TMAO levels.
  3. To evaluate the effect of dietary interventions on the amount of TMAO generated from gut flora using stable-isotope-labelled choline, carnitine, and betaine in subjects with elevated circulating TMAO levels.

Condition diet modification, dietary interventions, Dietary Modification, nutrition intervention, nutritional interventions, Cardiovascular Risk Factor, dietary intervention
Treatment MeLT Dietary intervention, TLC Dietary intervention, MeLT dietary intervention with TMAO
Clinical Study IdentifierNCT02016430
SponsorThe Cleveland Clinic
Last Modified on19 November 2021


Yes No Not Sure

Inclusion Criteria

Men and women age 18 years or above
Elevated TMAO metabolizers (>5 M) based on screening test
Willing to remain on aspirin or able to be off aspirin or aspirin products for 1 week prior to starting study and staying on the same aspirin regimen during the duration of the 12-week study
Willing to sign consent form or to follow study protocol, which includes 12-week dietary modification

Exclusion Criteria

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
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
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Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

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If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

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Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

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