Oral Carnitine Challenge Test Guides Personalized Nutrition for CV Patients

Study Overview
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Brief Summary
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The investigators plan to use the recently developed oral carnitine challenge test (OCCT) as a tool to exam individual's trimethylamine N-oxide (TMAO) production capacity from their gut microbiota. By using data collected by OCCT, the investigators defined subjects as high-TMAO producer or low-TMAO producer and apply low carnitine/choline diet as dietary intervention for the high-TMAO producers. After dietary intervention for two months, the investigators conducted OCCT for the participants and compare the TMAO production capacity before and after the dietary intervention.

Detailed Description
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Patients diagnosed with cardiovascular disease at the CV clinics are being recruited to undergo the Oral Carnitine Challenge Test (OCCT) to assess the TMAO production capacity of their gut microbiota. Participants identified as high-TMAO producers will be invited to partake in a two-month vegetarian diet intervention, supervised by a registered dietitian, followed by a three-month period of reverting to their regular diet. The OCCT will be conducted before and after the vegetarian diet intervention, as well as after the diet recovery phase. Fecal samples will be collected and analyzed at the baseline, in the second month, and in the fifth month of the study.

Official Title
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Investigation on Clinical Application of Oral Carnitine Challenge Test as a Guidance of Personalized Nutrition for Patients With Cardiovascular Disease

Conditions
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Dietary Modification, Cardiovascular Diseases

Intervention / Treatment
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* Behavioral: Vegetarian diet intervention


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient with risks of cardiovascular disease (CAD) or CAD patients proved by coronary angiography Exclusion Criteria: age < 20, hx of GI surgery, hx of malignancy, antibiotic or probiotic or carnitine supplement use within one month, liver cirrhosis, end stage chronic renal disease

Ages Eligible for Study
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Minimum Age: 20 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Interventional Model Description: Participants identified as high-TMAO producers through the oral carnitine challenge test will be invited to participate in a two-month vegetarian diet intervention.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Vegetarian diet intervention<br>Patients identified as high-TMAO producers through the oral carnitine challenge test will be invited to participate in a two-month vegetarian diet intervention, supervised by a registered dietitian. | Behavioral: Vegetarian diet intervention<br>* Patients will received dietary education and supervision by dietician to avoid high carnitine/choline foods including red meat, eggs...etc.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| TMAO production capacity | TMAO production capacity is measured by calculating the area under the curve of TMAO levels (quantification by LC-MS/MS) during the procedure of oral carnitine challenge test | Baseline, at the second month (following a two-month vegetarian diet intervention), and at the fifth month (after resuming a regular diet for three months). | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Compositional and functional changes of gut microbiota | The compositional and functional changes of gut microbiota will be evaluated by shotgun metagenome sequencing. Taxonomy will be calculated as relative abundance of species-level genome bins (SGBs) and specific bacteria genes will be quantified as Reads Per Kilobase per Million (RPKM). | Baseline, at the second month (following a two-month vegetarian diet intervention), and at the fifth month (after resuming a regular diet for three months). | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Gut microbiota, Trimethylamine N-oxide, Oral carnitine challenge test, Cardiovascular disease