Heart & Health Study

March 20, 2026 updated by: USDA, Western Human Nutrition Research Center

Variation in the ALOX5 Gene and Response to Omega-3 Fatty Acid Supplements

We hope to learn more about why certain people have higher levels of the 5-LO protein and whether taking fish oil supplements gives such individuals greater protection than others against cardiovascular disease. The 5-LO protein is important in the development of heart disease because it converts a type of oil from meat into a compound that can cause inflammation in blood vessels. This inflammation is a major cause of heart disease.

Researchers think that people with higher levels of a protein called 5-LO in their white blood cells may have a healthier response to using fish oil supplements than do people with lower levels of this protein.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Fish oil supplements will be given to subjects with different variants in the promoter region of the arachidonate 5-lipoxygenase (ALOX5) gene and outcome measures will be evaluated after 6 wk of supplementation. These outcomes include ALOX5 protein levels (also called 5-lipoxygenase, or 5-LO), leukotriene levels, markers of inflammation, and blood lipids. The 5-LO enzyme converts arachidonic acid (AA) to leukotrienes that promote inflammation. Subjects with different promoter variants are hypothesized to have different basal or stimulated levels of 5-LO expression. Preliminary data suggests that subjects with a promoter variant that causes increased 5-LO expression also may have a "better" anti-inflammatory or lipid-lowering response to fish oil supplements. The homozygous variant genotype is much more common in African Americans than other groups thus we propose to conduct the study in African Americans. The fish oil eicosapentaenoic acid (EPA) competitively inhibits conversion of AA to pro-inflammatory 4-series leukotrienes.

The grant proposes to conduct a community-based, double-masked, randomized, placebo-controlled trial; n = 15/group, total = 166 (genotypes 44 will have n = 8). The intervention group will receive 5.0 g/d fish oil concentrate (3.0 g/d EPA + DHA) for 6 wk. The study will be conducted in Oakland, Davis, and Sacramento, California where African Americans 20 - 59 y of age without serious chronic disease will be recruited.

A recent observational study indicates that subjects with a variant allele for ALOX5 may be at greater risk for cardiovascular disease and, at the same time, may derive a greater benefit from omega-3 fatty acid supplements than do subjects homozygous for the common allele. The variant alleles are less common in the white population (18%) than in the black population (52%). Since African Americans have a higher prevalence of cardiovascular disease and of the ALOX5 variant alleles, as shown in epidemiologic studies, they may have a greater benefit from omega-3 supplementation in the reduction of inflammation and cardiovascular risk factors. Recruitment will be conducted through the community service, Ethnic Health Institute (EHI), of Alta Bates Summit Medical Center in conjunction with UCD, and outreach efforts from the USDA, ARS, Western Human Nutrition Research Center (WHNRC) at UC Davis. We will determine if subjects with one or two variant ALOX5 alleles have higher ALOX5 gene expression, higher production of AA-derived leukotrienes, and a better response to omega-3 supplements than do subjects homozygous for the common allele.

Study Type

Interventional

Enrollment (Estimated)

166

Phase

  • 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
    • California
      • Davis, California, United States, 95616
        • UC Davis, Western Human Nutrition Research Center
      • Oakland, California, United States, 94609
        • Ethnich Health Institute
      • Sacramento, California, United States, 95820
        • UC Davis (TICON-1)

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

Ages Eligible for Study

20 years to 59 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • African-American, Black, or persons of African Descent
  • Generally Healthy
  • 20 - 59 years of age

Exclusion Criteria:

  • Chronic Diseases (Heart disease, cancer, diabetes, etc.)
  • Smoke > 14 cigarettes per week
  • Consume > 14 alcoholic drinks per week
  • Pregnant Women

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: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: 1
Dietary supplement: Fish Oil
capsules, 5.0 g/d fish oil concentrate (3.0 g/d EPA + DHA), 6 weeks
Placebo Comparator: 2
Dietary supplement: Placebo
capsule, 5.0 g/d corn/soybean oil (50/50 mixture), 6 weeks

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
(a) ALOX5 mRNA and protein in resting and stimulated cultures of purified monocytes and purified granulocytes (b) Arachidonic acid-derived leukotrienes in resting and stimulated cultures of whole blood, purified monocytes and purified granulocytes
Time Frame: 6 weeks
6 weeks

Secondary Outcome Measures

Outcome Measure
Time Frame
Proinflammatory cytokines, C-reactive protein, triglycerides, glucose and insulin in plasma, and resting heart rate 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

USDA, Western Human Nutrition Research Center

Collaborators

University of Southern California
University of California, Davis
National Center for Complementary and Integrative Health (NCCIH)
Office of Dietary Supplements (ODS)
USDA Beltsville Human Nutrition Research Center
Alta Bates Summit Medical Center

Investigators

  • Principal Investigator: Charles B Stephensen, PhD, UC Davis & U.S. Department of Agriculture

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

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

December 1, 2006

Primary Completion (Actual)

July 1, 2008

Study Completion (Actual)

July 1, 2008

Study Registration Dates

First Submitted

September 5, 2007

First Submitted That Met QC Criteria

September 25, 2007

First Posted (Estimated)

September 27, 2007

Study Record Updates

Last Update Posted (Actual)

March 25, 2026

Last Update Submitted That Met QC Criteria

March 20, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • R21AT003411-01A1 (U.S. NIH Grant/Contract)

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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