Cardioprotective Effects of Omega-3 Fatty Acids Supplementation in Healthy Older Subjects Exposed to Air Pollution Particles

August 5, 2025 updated by: Haiyan Tong, Environmental Protection Agency (EPA)
Exposure to ambient levels of air pollution increases cardiovascular morbidity and mortality. Advanced age is among the factors associated with susceptibility to the adverse effects of air pollution. Dietary fatty acid supplementation has been shown to decrease cardiovascular risk through multiple mechanisms. This study evaluated the efficacy of supplementation with marine fish oil or olive oil in protecting against cardiovascular effects induced by controlled exposure of middle-aged healthy volunteers to concentrated ambient air pollution particles. Subjects (ages 50 to72 years), were randomly assigned to receive 3 g/d of fish oil (1.2 g eicosapentaenoic acid and 0.82 g docosahexaenoic acid), or olive oil (3g/d) for 28 d. Subjects were then exposed to concentrated ambient air pollution particles or filtered air for 2 hr on sequential days. Heart rate variability (HRV), plasma lipids, coagulation markers, and endothelial function measured by flow-mediated dilation of the brachial artery (FMD) were assessed pre-, immediately post-, and 20 hr post-exposure.

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.

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.
29

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

  • United States
    • North Carolina
      • Chapel Hill, North Carolina, United States, 27514
        • EPA Human Studies Facility

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

Yes

Description

Inclusion Criteria:

  • Age 50-75 years old generally healthy male and female.
  • Normal resting electrocardiogram.
  • Oxygen saturation greater than 94% at the time of physical exam.

Exclusion Criteria:

  • A history of angina, cardiac arrhythmias, congestive heart failure, and ischemic myocardial infarction or coronary bypass surgery.
  • Cardiac pacemaker.
  • Uncontrolled hypertension (> 150 systolic, > 90 diastolic).
  • Neurodegenerative diseases such as Parkinson's and Alzheimer disease.
  • A history of chronic illnesses such as diabetes, cancer (possible exception for history of nonmelanoma skin cancer), rheumatologic diseases, immunodeficiency state, significant chronic respiratory diseases such as chronic obstructive pulmonary disease or severe asthma.
  • A history of migraine headache.
  • History of bleeding diathesis.
  • Currently taking beta-blockers to control hypertension and/or arrhythmias.
  • Use of oral anticoagulants.
  • Participants must refrain from all over-the-counter nonsteroidal anti-inflammatory drugs for a period of two weeks prior to exposure. Low-dose aspirin will be acceptable. Medications not specifically mentioned here may be reviewed by the investigators prior to a participant's inclusion in the study.
  • Allergies to fish or omega-3 fatty acids.
  • Subjects are on prescriptions taking omega-3 fish oil as therapy.
  • Subjects will be required to avoid taking omega-3 fatty acids or having more than one 4-6 oz/serving of all types of fish and shellfish, walnuts, flaxseeds and flaxseed oil, rapeseed oil, canola oil, soybeans and soy products, omega-3 fortified eggs, and cod liver oil for two weeks before and during the study.
  • Subjects will be required to avoid taking antioxidants (e.g., beta-carotene, selenium, vitamin C, vitamin E, zinc) for two weeks before and during the study.
  • Subjects will be required to use olive oil exclusively for cooking, dressings, and sauces during the study and to avoid other vegetable oils because of their omega-3 contents.
  • Because of reported cardioprotective effects of red wine, subjects will be required to avoid drinking red wine during the study.
  • Subjects who are currently smoking or have smoking history within 1 year of study (defined as more than one pack of cigarettes in the past year) or have a greater than/equal to a 5 pack year smoking history.
  • No exposure will be conducted within 2 weeks of a respiratory tract infection.
  • Subject is pregnant, attempting to become pregnant or breastfeeding.
  • Unspecified illnesses, which in the judgment of the investigators might increase the risk associated with PM inhalation will be a basis for exclusion.
  • Have an allergy to latex.
  • History of skin allergy to tape or electrodes.

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: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

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: Fish oil
Dietary supplement: Fish oil
Subjects (ages 50 to 75 years), were randomly assigned to receive 3 g/d of fish oil (1.2 g eicosapentaenoic acid and 0.82 g docosahexaenoic acid) for 28 d.
Experimental: Olive oil
Dietary supplement: Olive oil
Subjects (ages 50 to 75 years) were randomly assigned to receive 3 g/d of olive oil for 28 d.

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
Heart rate variability changes
Time Frame: pre-, immediately post-, and 20 hr post-air pollution exposure
pre-, immediately post-, and 20 hr post-air pollution exposure

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
endothelial function changes measured by flow-mediated dilation of the brachial artery
Time Frame: pre-, immediately post-, and 20 hr post-air pollution exposure
pre-, immediately post-, and 20 hr post-air pollution exposure

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.
Environmental Protection Agency (EPA)

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

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.
June 1, 2009

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.
August 1, 2010

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.
December 1, 2016

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).
September 26, 2011

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.
September 27, 2011

First Posted (Estimated)

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.
September 28, 2011

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.
August 8, 2025

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.
August 5, 2025

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.
August 1, 2025

More Information

Terms related to this study

Keywords

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.
  • Omegacon

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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