An interventional study of Fish Oil and Placebo in Heart Disease, sponsored by USDA, Western Human Nutrition Research Center. Completed at 3 sites in United States. Open to participants aged 20 Years to 59 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-25.
Sponsored by USDA, Western Human Nutrition Research Center · Not applicable, Interventional, and Prevention
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.
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.
2,135 studies on the registry are indexed under Heart Diseases; 252 are open to participants now.
This study's planned enrollment of 166 is above the median of 129 across 931 interventional studies indexed under Heart Diseases.
Browse Heart Diseases studies →USDA, Western Human Nutrition Research Center is the lead sponsor of 54 studies on the registry; 1 is open to participants now.
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Exclusion Criteria:
Dietary Supplement: Fish Oil
Dietary Supplement: Placebo
capsules, 5.0 g/d fish oil concentrate (3.0 g/d EPA + DHA), 6 weeks
capsule, 5.0 g/d corn/soybean oil (50/50 mixture), 6 weeks
(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
Proinflammatory cytokines, C-reactive protein, triglycerides, glucose and insulin in plasma, and resting heart rate and blood pressure
Time frame: 6 weeks
The record gives a start of Dec 2006, a primary completion of Jul 2008 and a completion of Jul 2008. It does not say whether these dates are actual or estimated.
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This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Fish Oils
USDA, Western Human Nutrition Research Center