Dietary ModificationEarly Phase 1CARNIVALNCT01731236
CARNIVAL Study: Gut Flora Dependent Metabolism of Dietary CARNItine and Phosphatidylcholine and cardioVAscuLar Disease
A Early Phase 1 study testing Carnitine, Choline and Antibiotics in people with Dietary Modification, run by The Cleveland Clinic at 1 site in United States.
Trial summary
The principal goal for the study is to examine the role gut flora plays in modulating metabolism of dietary carnitine and choline in humans. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Dietary Modification
- What is being tested?
- Carnitine, Choline and Antibiotics
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 100 participants
- Where
- 1 siteUnited States
- Study dates
- 11 Feb 2011to Dec 2029
- Phase
- Early Phase 1
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Men and women age 18 years or above.
- Able to provide informed consent and comply with study protocol
Who cannot join
- Significant chronic illness or end-organ dysfunction, including known history of heart failure, renal failure, pulmonary disease, hematologic diseases or pregnancy.
- Active infection or received antibiotics within 2 months of study enrollment
- Use of Over-The-Counter (OTC) probiotic within past 2 months, or ingestion of yogurt within past 7 days
- Chronic gastrointestinal disorders, or intolerance to probiotic therapy
- Having undergone Bariatric procedures or surgeries such as gastric banding or bypass
Trial locations and contacts
1 site in 1 country.
About this study
The principal goal for the study is to examine the role gut flora plays in modulating metabolism of dietary carnitine and choline in humans.
Read the detailed description
The principal goal for the study is to examine the role gut flora plays in modulating metabolism of dietary trimethylamine nutrients in humans. We have recently shown that dietary intake of two trimethylamines abundant in animal products, carnitine and the choline group of phosphatidylcholine (PC), are mechanistically linked to cardiovascular disease risk. We wish to further explore the metabolism of these nutrients in humans, and to test the hypothesis that the intestinal micro flora (gut flora) plays a critical role in generation of metabolites from dietary carnitine and choline/PC linked to cardiometabolic disease. We further hypothesize that the production of specific metabolites of carnitine and choline/PC are influenced by the composition of gut flora, and these may be altered by the preceding dietary patterns of the subjects. We therefore wish to test whether dietary supplementation with carnitine and/or choline alters the metabolism of carnitine and choline/PC in subjects. We also hypothesize that transient suppression or modulation of gut flora via short-term broad spectrum antibiotic therapy, or by reconstitution of micro flora composition via probiotic therapy, in healthy subjects, can alter the metabolism of carnitine and choline/PC. We will also examine the impact of low dose aspirin on these pathways by examining subjects before versus after taking aspirin.
- Conditions
- Dietary Modification
- Being tested
- Carnitine, Choline, Antibiotics, Choline and Aspirin, Carnitine and Aspirin
- Keywords
- carnitine metabolism, gut flora, phosphatidylcholine
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
CarnitineDietary supplement
Group 1: Carnitine supplement for 2 months, No antibiotics, no aspirin for 3 months (1 month prior and during study)
CholineDietary supplement
Group 2: Choline supplement for 2 months, No antibiotics, no aspirin for 3 months (1 month prior and during study)
AntibioticsDrug
Also called Ciprofloxacin, Flagyl, Vancomycin, and Neomycin
Group 3: Carnitine or Choline for 2 months, antibiotic cocktail (Ciprofloxacin, Flagyl, Vancomycin, and Neomycin) for 1 week
Choline and AspirinDrug
Also called aspirin
Group 4: Choline supplement for 2 months plus aspirin 81 mg for 3 months (1 month prior to starting the study and 2 months during the study).
Carnitine and AspirinDrug
Also called aspirin
Group 5: Carnitine supplement for 2 months plus aspirin 81 mg for 3 months (1 month prior to starting the study and 2 months during the study).
| Study group | Role | What they receive |
|---|---|---|
| Carnitine (No antibiotics, No aspirin) | Active comparator | L-Carnitine 500 mg capsule by mouth, twice daily for 2 months. No aspirin for 1 month prior to starting study and remains off aspirin during study. Receives: Dietary Supplement: Carnitine |
| Choline (No Antibiotics, No aspirin) | Active comparator | Choline 500 mg capsule by mouth, twice daily for 2 months. No aspirin for 1 month prior to starting study and remains off aspirin during study. Receives: Dietary Supplement: Choline |
| Antibiotics | Active comparator | Antibiotics (Ciprofloxacin, Vancomycin, Metronidazole and Neomycin) Drug: Ciprofloxacin 500 mg, po, twice daily for 7 days (Other Names: Cipro)
Drug: Metronidazole 500 mg, po, twice daily for 7 days (Other Names: Flagyl, Noritate, Rosadan, Vandazole, Flagyl ER, Vitazol)
Drug: Vancomycin 125 mg, po, 4 times daily for 7 days (Other Names: Vancocin, Vancocin HCl, Pulvules, Vancoled, Novaplus, PremierPro Rx, Vancomycin HCl)
Drug: Neomycin 1 gram, po, four times daily for 7 days (Other Names: Aminoglycoside) Receives: Drug: Antibiotics |
| Choline and Aspirin | Active comparator | Choline supplement 500 mg capsule by mouth, twice daily for 2 months Drug: aspirin 81 mg by mouth, daily for 3 months (on aspirin for 1 month prior to starting study and 2 months with Choline supplementation during study)
Other Names:
Ecotrin, Bufferin, Ascriptin, Fasprin, Norwich Aspirin, Durlaza, Bayer Genuine Aspirin, Genacote, Bayer, Halfprin, Aspirtab, Aspir Low, Aspir-Trin Receives: Drug: Choline and Aspirin |
| Carnitine and Aspirin | Active comparator | Carnitine supplement 500 mg capsule by mouth, twice daily for 2 months Drug: aspirin 81 mg by mouth, daily for 3 months (on aspirin for 1 month prior to starting study and 2 months with Carnitine supplementation during study)
Other Names:
Ecotrin, Bufferin, Ascriptin, Fasprin, Norwich Aspirin, Durlaza, Bayer Genuine Aspirin, Genacote, Bayer, Halfprin, Aspirtab, Aspir Low, Aspir-Trin Receives: Drug: Carnitine and Aspirin |
What is being measured
The primary outcome is the main question the study is designed to answer.
Primary Outcome Measure
Plasma levels of carnitine and multiple gut flora metabolites
Measured: December 2017
Secondary outcomes (1)
Secondary Outcome Measures
Alterations in plasma levels of cardio-metabolic risk factors.
Measured: December 2017
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Nov 2012 (estimated)
- Study start11 Feb 2011
- Primary completionDec 2027 (estimated)
- Study completionDec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Dietary ModificationStudies of the same condition, open and under way.
- More trials run by The Cleveland ClinicThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Early Phase 1
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 100 participants (estimated)
Sponsor and investigators
- Lead sponsor
- The Cleveland Clinic
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Stanley L Hazen, MD, PhD, The Cleveland Clinic
- Investigators
- Stanley L Hazen, MD, PhD, Principal investigator, The Cleveland Clinic
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT01731236
- Sponsor's protocol ID
- 10-544
- Acronym
- CARNIVAL
- Status last verified
- Mar 2026
- First submitted
- 23 Jan 2012
- Last updated
- 23 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- Individual data sharing
- No
Publications
Koeth RA, Lam-Galvez BR, Kirsop J, Wang Z, Levison BS, Gu X, Copeland MF, Bartlett D, Cody DB, Dai HJ, Culley MK, Li XS, Fu X, Wu Y, Li L, DiDonato JA, Tang WHW, Garcia-Garcia JC, Hazen SL. l-Carnitine in omnivorous diets induces an atherogenic gut microbial pathway in humans. J Clin Invest. 2019 Jan 2;129(1):373-387. doi: 10.1172/JCI94601. Epub 2018 Dec 10.
PubMed 30530985
Study at a glance
From the registry record, last updated by the sponsor on 23 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- CARNIVAL Study: Gut Flora Dependent Metabolism of Dietary CARNItine and Phosphatidylcholine and cardioVAscuLar Disease
- ClinicalTrials.gov ID
- NCT01731236
- Acronym / sponsor ID
- CARNIVAL / 10-544
- Conditions
- Dietary Modification
- Keywords
- carnitine metabolism, gut flora, phosphatidylcholine
- Phase
- Early Phase 1
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- The Cleveland ClinicUniversity, hospital or other
- Study start
- 11 Feb 2011 (actual)
- Primary completion
- Dec 2027 (estimated)
- Study completion
- Dec 2029 (estimated)
- First posted
- 21 Nov 2012 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The principal goal for the study is to examine the role gut flora plays in modulating metabolism of dietary carnitine and choline in humans.
Detailed description
The principal goal for the study is to examine the role gut flora plays in modulating metabolism of dietary trimethylamine nutrients in humans. We have recently shown that dietary intake of two trimethylamines abundant in animal products, carnitine and the choline group of phosphatidylcholine (PC), are mechanistically linked to cardiovascular disease risk. We wish to further explore the metabolism of these nutrients in humans, and to test the hypothesis that the intestinal micro flora (gut flora) plays a critical role in generation of metabolites from dietary carnitine and choline/PC linked to cardiometabolic disease. We further hypothesize that the production of specific metabolites of carnitine and choline/PC are influenced by the composition of gut flora, and these may be altered by the preceding dietary patterns of the subjects. We therefore wish to test whether dietary supplementation with carnitine and/or choline alters the metabolism of carnitine and choline/PC in subjects. We also hypothesize that transient suppression or modulation of gut flora via short-term broad spectrum antibiotic therapy, or by reconstitution of micro flora composition via probiotic therapy, in healthy subjects, can alter the metabolism of carnitine and choline/PC. We will also examine the impact of low dose aspirin on these pathways by examining subjects before versus after taking aspirin.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 5
| Arm | Type | Receives |
|---|---|---|
| Carnitine (No antibiotics, No aspirin) | Active comparator | Dietary Supplement: CarnitineL-Carnitine 500 mg capsule by mouth, twice daily for 2 months. No aspirin for 1 month prior to starting study and remains off aspirin during study. |
| Choline (No Antibiotics, No aspirin) | Active comparator | Dietary Supplement: CholineCholine 500 mg capsule by mouth, twice daily for 2 months. No aspirin for 1 month prior to starting study and remains off aspirin during study. |
| Antibiotics | Active comparator | Drug: AntibioticsAntibiotics (Ciprofloxacin, Vancomycin, Metronidazole and Neomycin) Drug: Ciprofloxacin 500 mg, po, twice daily for 7 days (Other Names: Cipro) Drug: Metronidazole 500 mg, po, twice daily for 7 days (Other Names: Flagyl, Noritate, Rosadan, Vandazole, Flagyl ER, Vitazol) Drug: Vancomycin 125 mg, po, 4 times daily for 7 days (Other Names: Vancocin, Vancocin HCl, Pulvules, Vancoled, Novaplus, PremierPro Rx, Vancomycin HCl) Drug: Neomycin 1 gram, po, four times daily for 7 days (Other Names: Aminoglycoside) |
| Choline and Aspirin | Active comparator | Drug: Choline and AspirinCholine supplement 500 mg capsule by mouth, twice daily for 2 months Drug: aspirin 81 mg by mouth, daily for 3 months (on aspirin for 1 month prior to starting study and 2 months with Choline supplementation during study) Other Names: Ecotrin, Bufferin, Ascriptin, Fasprin, Norwich Aspirin, Durlaza, Bayer Genuine Aspirin, Genacote, Bayer, Halfprin, Aspirtab, Aspir Low, Aspir-Trin |
| Carnitine and Aspirin | Active comparator | Drug: Carnitine and AspirinCarnitine supplement 500 mg capsule by mouth, twice daily for 2 months Drug: aspirin 81 mg by mouth, daily for 3 months (on aspirin for 1 month prior to starting study and 2 months with Carnitine supplementation during study) Other Names: Ecotrin, Bufferin, Ascriptin, Fasprin, Norwich Aspirin, Durlaza, Bayer Genuine Aspirin, Genacote, Bayer, Halfprin, Aspirtab, Aspir Low, Aspir-Trin |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Men and women age 18 years or above.
- Able to provide informed consent and comply with study protocol
Key exclusion criteria (5 listed)
- Significant chronic illness or end-organ dysfunction, including known history of heart failure, renal failure, pulmonary disease, hematologic diseases or pregnancy.
- Active infection or received antibiotics within 2 months of study enrollment
- Use of Over-The-Counter (OTC) probiotic within past 2 months, or ingestion of yogurt within past 7 days
- Chronic gastrointestinal disorders, or intolerance to probiotic therapy
- Having undergone Bariatric procedures or surgeries such as gastric banding or bypass
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| CarnitineGroup 1: Carnitine supplement for 2 months, No antibiotics, no aspirin for 3 months (1 month prior and during study) | Dietary supplement | Carnitine (No antibiotics, No aspirin) |
| CholineGroup 2: Choline supplement for 2 months, No antibiotics, no aspirin for 3 months (1 month prior and during study) | Dietary supplement | Choline (No Antibiotics, No aspirin) |
| AntibioticsAlso: Ciprofloxacin, Flagyl, Vancomycin, and NeomycinGroup 3: Carnitine or Choline for 2 months, antibiotic cocktail (Ciprofloxacin, Flagyl, Vancomycin, and Neomycin) for 1 week | Drug | Antibiotics |
| Choline and AspirinAlso: aspirinGroup 4: Choline supplement for 2 months plus aspirin 81 mg for 3 months (1 month prior to starting the study and 2 months during the study). | Drug | Choline and Aspirin |
| Carnitine and AspirinAlso: aspirinGroup 5: Carnitine supplement for 2 months plus aspirin 81 mg for 3 months (1 month prior to starting the study and 2 months during the study). | Drug | Carnitine and Aspirin |
Primary outcome
Primary Outcome Measure
Time frame: December 2017
Plasma levels of carnitine and multiple gut flora metabolites
1 secondary outcome
Secondary Outcome Measures
Time frame: December 2017
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Mar 2026.
- Derived from this study: PubMed 30530985Koeth RA, Lam-Galvez BR, Kirsop J, Wang Z, Levison BS, Gu X, Copeland MF, Bartlett D, Cody DB, Dai HJ, Culley MK, Li XS, Fu X, Wu Y, Li L, DiDonato JA, Tang WHW, Garcia-Garcia JC, Hazen SL. l-Carnitine in omnivorous diets induces an atherogenic gut microbial pathway in humans. J Clin Invest. 2019 Jan 2;129(1):373-387. doi: 10.1172/JCI94601. Epub 2018 Dec 10.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Stanley L Hazen, MD, PhD principal investigator
The Cleveland Clinic
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Early Phase 1 study testing Carnitine, Choline and Antibiotics in people with Dietary Modification, run by The Cleveland Clinic at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 23 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Primary Outcome Measure (time frame: December 2017). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT01731236, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Mar 2026.