Fish Oil's Heart Health Claims Called Into Question

Fish oil supplements' heart-healthy molecules may not be easily digestible

They're a billion-dollar industry, but are fish oil supplements all they're cracked up to be? Maybe not.

While previous studies have found that fish oil contains properties that may benefit heart health, a new study found that the heart-healthy molecules in fish oil supplements may not actually be easily digestible by humans.

Researchers from the University of Pennsylvania (UPenn) set out to determine whether those who consumed fish oil supplements would benefit from these heart-healthy molecules, otherwise known as specialized pro-resolving mediators (SPMs).

SPMs have been shown to calm inflammation, which can promote heart health.

"There are few reliable data based on such rigorous detection methods... confirming that SPMs form in humans after taking fish oil pills," said study co-author Carsten Skarke, MD, an assistant professor of medicine at UPenn, in a press release.

Inflammation is the immune system's response to foreign substances, such as bacteria colonizing a wound or a splinter in your finger.

This is not always a helpful response of the body, however.

Chronic low-grade inflammation can lead to clogged arteries, which sets the stage for heart attacks, most strokes and cardiovascular disease.

SPMs are found in Omega-3 fatty acids, which are most commonly found in fish, such as salmon, tuna and halibut.

Omega-3s are extracted from fish and are eventually turned into concentrated fish oil supplements.

Dr. Starke and team found a lack of SPMs in the systems of study participants who consumed high amounts of fish oil supplements. Participants who took a fish oil dose after a bacterial infection also did not see a decrease in inflammation.

This may mean that the heart-healthy molecules found in fish oil supplements are not easily digestible by humans.

According to Dr. Starke and team, Omega-3s derived from eating fish are more easily digested and absorbed in the body than those found in supplements.

The American Heart Association recommends eating fish at least 2 times per week as part of a heart healthy diet.

This study was published July 30 in the Journal of Lipid Research.

The American Heart Association, the Alexander von Humboldt Foundation and the National Center for Research Resources funded this research.

No conflicts of interest were disclosed.