Omega-3 benefits may vanish quickly after you stop

Scientists in Finland explored how eicosapentaenoic acid (EPA), an omega-3 fatty acid found in fish oil, affects metabolism and blood lipid levels in healthy adults.

While EPA is already recognized for lowering cardiovascular risk in people with high cholesterol or heart disease, its effects in otherwise healthy individuals have not been well understood. Little was also known about how EPA becomes incorporated into lipoproteins, the particles that transport fat molecules through the bloodstream.

High-Dose Supplement Study Reveals Wide Variation

In this research, 38 volunteers were given unusually high doses of EPA supplements. Blood samples were collected before, during, and after supplementation to observe how the body processed the fatty acid. The results showed large differences among participants in how their bodies responded to EPA.

"The samples taken during supplementation clearly show the effect of EPA on all participants. Having said that, all samples were different among the group. In other words, each individual has a unique lipoprotein lipidome in their circulation, a 'lipid fingerprint', if you will, that persisted despite EPA supplementation," explains Professor Katariina Öörni, one of the lead authors from the Faculty of Biological and Environmental Sciences, University of Helsinki, and the Wihuri Research Institute.

The researchers confirmed that EPA is absorbed efficiently, causing a sharp rise in its concentration in the blood. However, the levels declined quickly once supplementation stopped. The strongest changes were observed in participants who started with lower baseline EPA levels.

In addition, EPA improved blood lipid profiles and reduced the tendency of lipoproteins to attach to the walls of arteries -- an important factor in preventing atherosclerosis.

Short-Term Effects and Future Research

Because the study lasted only a short time, it did not measure long-term outcomes. Still, the findings reveal that EPA can alter blood lipid composition and influence early risk mechanisms for atherosclerosis even in healthy people.

"The findings highlight the importance of metabolism in the prevention of cardiovascular diseases. EPA's effects varied more between individuals than we expected. We also demonstrated that these effects dissipate quickly, which is good to know in case EPA were to have adverse effects," notes Doctoral Researcher Lauri Äikäs.

Next, the team plans to study how EPA supplementation affects inflammatory cells and the production of lipid mediators that help control inflammation.

"It's interesting to see how, for instance, dietary changes affect lipoprotein quality, or the individual lipid fingerprint," Öörni adds.