Alpha-Linolenic Acid and Inflammatory Markers

December 13, 2023 updated by: Harvard School of Public Health (HSPH)

Effect of Alpha-Linolenic Acid on Blood Markers of Inflammation

The optimal type of oil to prevent cardiovascular disease (CVD) is uncertain. In general, unsaturated oils with higher content of cis-monounsaturated fatty acids (MONO) or cis-polyunsaturated fatty acids (PUFA) are preferable over those rich in saturated fatty acids. However, unsaturated oils can vary in their relative contents of n-6 and n-3 fatty acids (specifically alpha-linolenic acid (ALA)). Some investigators advocate that oils rich in ALA are cardioprotective, while others suggest that optimal cardioprotective effects can only be obtained when oils are lower in n-6 fatty acids (mainly linoleic acid) in addition to being higher in ALA. It is hypothesized that increased ALA would result in beneficial effects on inflammatory markers. The objective of this trial is to establish definitively the biological effects of ALA with and without reductions in linoleic acid on inflammatory markers linked to CVD.

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

This study is a dietary trial that examines the effects of increasing ALA by 2 gr or 4 gr per day, with and without decreasing linoleic acid, on inflammatory markers linked to CVD. Trial participants (n=136), approximately 50% women, 50% men) are age 50 and older and living in the town of Montana, Bulgaria during the study. The study uses a double-blinded placebo-controlled, randomized cross-over design. Combinations of two oils that are considered healthy (sunflower and olive) and an ALA supplement containing either 2 or 4 gr of ALA (supplied as flaxseed oil) or placebo are consumed for 6 weeks each: sunflower-ALA (high linoleic-low ALA), sunflower-placebo (high linoleic-low ALA), olive-ALA (low-linoleic-high ALA) and olive-placebo (low linoleic-low ALA). The participants are indicated to keep their usual diet and physical activity through-out the study. The primary endpoints are plasma levels of inflammatory markers. Secondary endpoints include systolic and diastolic blood pressure, and plasma levels of LDL cholesterol, HDL cholesterol and triglycerides.

SPECIFIC AIMS

To determine the effect of increasing ALA by 2 or 4 gr per day in the context of a diet that that is high in linoleic acid (~13% energy) on inflammatory markers. The ALA effect will be tested by comparing ALA supplement vs. placebo while using sunflower oil for cooking at home. We hypothesize that ALA has favorable effects on inflammatory markers in the context of a diet that is high in linoleic acid.

To determine the effect of increasing ALA by 2 or 4 gr per day in the context of a diet that that is low in linoleic acid (~6% energy) on inflammatory markers. The ALA effect will be tested by comparing ALA supplement vs. placebo while using olive oil for cooking at home. We hypothesize that ALA has favorable effects on inflammatory markers in the context of a diet that is low in linoleic acid.

SECONDARY AIMS

To determine the effect of reducing linoleic acid from a high level (~13% energy) to a low level (~6% energy) while keeping ALA at a high level (2 or 4 gr per day) on plasma levels of inflammatory markers. The reduction in linoleic acid will be tested by comparing sunflower to olive oil while taking the ALA supplement. We hypothesize that reducing linoleic acid does not affect inflammatory markers when ALA intake is high.

To determine the effect of reducing linoleic acid from a high level (~13% energy) to a low level (~6% energy) while keeping ALA at a low level (placebo) on plasma levels of inflammatory markers. The reduction in linoleic acid will be tested by comparing sunflower to olive oil while taking the placebo. We hypothesize that reducing linoleic acid does not affect inflammatory markers when ALA intake is low.

To determine whether the intervention contrasts specified in the specific aims and secondary aims 1 & 2 affect plasma levels of LDL cholesterol, HDL cholesterol and triglycerides and blood pressure.

We hypothesize that ALA has favorable effects on plasma triglycerides and blood pressure compared to placebo regardless of whether linoleic acid is high or low.

We hypothesize that lowering linoleic acid has favorable effects on plasma HDL cholesterol but unfavorable effects on LDL cholesterol,regardless of whether ALA is high or low.

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.
130

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

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 and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age 50 or older at time of enrollment
  • Willing to cook and eat foods prepared exclusively with the study oils and nothing else every day of the week at least 2 meals per day for 24 weeks
  • Willing to eat no more than one meal per week prepared out of the home
  • Willingness to take 4 or 8 capsules with ALA or placebo every day for 24 weeks
  • Willingness to provide personal and next of kin address and phone number for follow-up visits to the home.
  • Willingness to complete measurement procedures and blood draws.
  • Ability and willingness to provide informed consent to be screened and to take part of the study.

Exclusion Criteria:

Medication Exclusions

• Unstable dose of medications during the past 2 months that raise or lower blood pressure, lipids or glucose. Unstable dose is a dose change in the past 6 months or less than 6 months of treatment.

Medical History Exclusions

  • Active or prior CVD (stroke, MI, PTCA, CABG, congestive heart failure, symptomatic ischemic heart disease (angina), or CVD-related therapeutic procedure).
  • Cancer diagnosis or treatment in past two years (however, persons with non-melanoma skin cancer, localized breast cancer, or localized prostate cancer can enroll if they did not require systemic chemotherapy)
  • Active inflammatory bowel disease, malabsorption, or major GI resection
  • Chronic renal disease
  • Any serious illness not otherwise specified that would interfere with participation
  • Stage 2 hypertension (SBP > 160 or DBP > 100 mmHg) based on the mean of 3 measurements on the screening visit, as well as a systolic BP > 170 or diastolic BP > 105 at any of the measurements

Other Exclusions

  • Eat fish more than once per week including canned fish
  • Significant oil preferences, intolerances, dietary habits, or dietary requirements that would interfere with adherence
  • Planning to leave the area for more than two weeks prior to the anticipated end of participation
  • Current participation in another study that manipulates diet or that will affect the outcome of this study
  • Taking vitamin, vegetable oil, fish-oil, weight-loss, soy, mineral, or herbal supplements that cannot be stopped
  • Unable to measure blood pressure (due to arm circumference > 50 cm)
  • Investigator judgment (e.g. for concerns over adherence, or follow-up or for inappropriate behavior)

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: Crossover Assignment
  • Masking: Triple

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.
Active Comparator: High ALA-Low Linoleic
Dietary supplement: Flaxseed oil-Olive oil
2 or 4 gr per day alpha-linolenic acid pill and olive oil used for cooking
Placebo Comparator: Low ALA-Low Linoleic
Dietary supplement: Olive oil-olive oil
1 gr olive oil pill and olive oil used for cooking
Active Comparator: High ALA-High Linoleic
Dietary supplement: Flaxseed oil-sunflower oil
2 or 4 gr per day alpha linolenic acid pill and sunflower oil used for cooking
Placebo Comparator: Low ALA-High Linoleic
Dietary supplement: Olive oil-sunflower oil
1 gr olive oil pill and sunflower oil used for cooking

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
Markers of inflammation
Time Frame: 6 weeks
6 weeks

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
Plasma lipids and blood pressure
Time Frame: 6 weeks
6 weeks

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.
Harvard School of Public Health (HSPH)

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.
February 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, 2009

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.
August 1, 2009

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).
August 27, 2009

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.
August 27, 2009

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.
August 28, 2009

Study Record Updates

Last Update Posted (Estimated)

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.
December 19, 2023

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.
December 13, 2023

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.
December 1, 2023

More Information

Terms related to this study

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.
  • P-16261-101

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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