The Use of L-arginine to Mitigate the Cardiovascular Effects of Exposure to Traffic-related Air Pollution

March 8, 2021 updated by: Shaowei Wu, Peking University

The Use of L-arginine to Mitigate the Cardiovascular Effects of Exposure to Traffic-related Air Pollution: A Randomized, Double-blind, Placebo-controlled Trial

The present study is aimed to investigate whether oral L-arginine supplementation reduces the adverse cardiovascular effects of exposure to traffic-related air pollution among a group of non-smoking adults with elevated blood pressure.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The present study is designed as a randomized, double-blind, placebo-controlled trial of L-arginine (L-Arg, a precursor of nitric oxide in human body) supplement to counteract the acute cardiovascular effects of exposure to traffic-related air pollution among a group of non-smoking adults with elevated blood pressure. A large number of epidemiological studies have provided compelling evidence that exposure to traffic-related air pollution contributes to the increases in cardiovascular morbidity and mortality, and the mechanism of action includes vasoconstriction and cardiac ischemia. It is well known that nutritional factors are very important determinants of cardiovascular health. However, few studies have explored the joint effects of air pollution and nutritional factors on cardiovascular health. Existing data from many laboratory studies and small clinical trials suggest that L-Arg has beneficial effects on the cardiovascular system by lowering blood pressure and protecting myocardiocytes against external stimuli. The study will explore whether L-Arg supplement improves blood pressure levels and prevents potential cardiac ischemia upon acute exposure to traffic-related air pollution among high-risk individuals.

Dietary intakes, lifestyle habits, use of medication/dietary supplements, blood pressure, resting electrocardiogram and plasma parameters were assessed for potential eligible participants at screening visits. Over 500 participants completed the screening visits, and 118 of them were eligible after a 5-day L-Arg-free run-in period and willing to participate in the following intervention. Eligible participants were assigned to either the interventional group or control group using a computerized method with a randomized block design. They received 2 weeks (may float back and forth for 1-3 days due to scheduling issues) daily doses of either L-Arg (9g/day in 3 times) or placebo and undergo a 2-h exposure scenario (0900-1100 hours) of walking along a traffic road on the 14th day. Participants were counseled to maintain an isocaloric diet and to abstain from other L-Arg rich foods during the study. Concentrations of major traffic-related air pollutants, including particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM2.5), black carbon, and nitrogen dioxide, were measured from the beginning of the 2-h exposure scenario to 22h after exposure or during the 2-h exposure scenario, and primary and secondary outcome measures including blood pressure, ST-segment depression and plasma parameters were assessed repeatedly at various time points (depending on the parameters) around the 2-h exposure scenario. Other environmental factors, including noise, temperature and relative humidity, were also recorded during the 2-h exposure scenario and up to 22h after exposure.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
118

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

  • China
      • Beijing, China, 100091
        • Qinglongqiao Community Health Service Center
      • Beijing, China, 100191
        • Malianwa Community Health Service Center
      • Beijing, China, 100191
        • Shangdi Community Health Service Center

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

50 years to 75 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  1. Having elevated systolic blood pressure between 120-160 mmHg, and diastolic blood pressure between 65-100 mmHg, either with or without routine antihypertensive medications.
  2. Adults between 50 and 75 years of age, current non-smokers;
  3. Do not take routine vasoactive dietary supplements.

Exclusion Criteria:

  1. Hypertension with SBP>160 mmHg or DBP>100 mmHg, clinical diagnosis of cardiovascular disease (excluding hypertension), or other important chronic diseases such as coagulopathy, chronic obstructive pulmonary disease, asthma, gastrointestinal diseases, cancer or mental diseases;
  2. No routine use of vasoactive dietary supplements,or, if taking, willing to forego their use during the trial.
  3. Fasting LDL cholesterol≥4.92 mmol/L or total cholesterol≥6.21 mmol/L or HbA1c>9%;
  4. Liver or renal dysfunction;
  5. Acute coronary symptoms or unstable clinical manifestations within the past three months;
  6. Suffering from allergic diseases/known allergy to ingredients of L-Arg; or those who suffered from acute illness before start of the study;
  7. Alcohol or drug addiction;
  8. Hepatitis B / hepatitis C virus patient / carrier;
  9. History of organ transplants or major surgery in the past year;
  10. Exposed to occupational sources of air pollution;
  11. Unwilling or unable to provide informed consent or cooperate with all research related procedures.

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: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: L-Arg supplement group
Study participants in the group will take L-Arg supplement during the trial.
Dietary supplement: L-Arg supplement
L-Arg supplement will be prepared as pills, administered 9g each day in 3 times for 2 weeks.
Placebo Comparator: Control group
Study participants in the group will take placebo during the trial.
Dietary supplement: Placebo
Placebo will be prepared as pills (the same size, color and shape as of L-Arg), administered 3 times daily for 2 weeks.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Change in systolic and diastolic blood pressure from before the dietary intervention to before, during, 30min after and 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); before and during the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22h after the exposure scenario (15th day).
before taking L-Arg supplement/placebo (1st day); before and during the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22h after the exposure scenario (15th day).
Change in ST-segment depression from before the dietary intervention to before, during until 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); and 24 hours from the start of 2-h exposure scenario (14th day) until 22h after the exposure scenario (15th day)
before taking L-Arg supplement/placebo (1st day); and 24 hours from the start of 2-h exposure scenario (14th day) until 22h after the exposure scenario (15th day)
Change in ambulatory blood pressure during the 2-h exposure scenario (vs. before the dietary intervention)
Time Frame: during the 2-h exposure scenario (14th day)
during the 2-h exposure scenario (14th day)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Change in plasma L-Arg from before the dietary intervention to before, 30min after and 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
Change in plasma nitric oxide (including nitrate and nitrite) from before the dietary intervention to before, 30min after and 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
Change in plasma cyclic guanosine monophosphate from before the dietary intervention to before, 30min after and 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
Change in plasma C-reactive protein from before the dietary intervention to before, 30min after and 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
Change in plasma myeloperoxidase from before the dietary intervention to before, 30min after and 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
Change in pulse oxygen saturation from before the dietary intervention to before, 30min after and 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
Change in endothelial nitric oxide synthase from before the dietary intervention to before, 30min after and 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
Change in two related amino acids (citrulline and ornithine) in L-arg metabolic pathway from before the dietary intervention to before, 30min after and 22h after the 2-h exposure scenario
Time Frame: before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)
before taking L-Arg supplement/placebo (1st day); before the 2-h exposure scenario (14th day); 30min after the exposure scenario (14th day); and 22 hours after the exposure scenario (15th day)

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Peking University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Shaowei Wu, PhD, Peking University

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 2, 2018

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 4, 2019

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 31, 2020

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 31, 2018

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 8, 2018

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 15, 2018

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 10, 2021

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 8, 2021

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2021

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2017074

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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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