PHILADELPHIA, July 31 (UPI) -- The therapeutic benefits of synthetic fish oil supplements went undetected in the bodies of participants in a recent study, calling into question whether their use is relevant for health treatments.
Large studies in the past have supported the theory that omega-3 polyunsaturated fatty acids from fish can reduce inflammation in hearts and blood vessels. As a result, synthetic forms of the oils, called specialized pro-resolving mediators, or SPMs, have been produced so people can regularly consume larger amounts without having to drastically increase how much fish they eat.
Researchers in a new study, published in the Journal of Lipid Research, said that while previous research on synthetic fish oils showed their efficacy on cells outside the human body, they couldn't find the presence or benefits of omega-3 polyunsaturated fatty acids in people who took supplements.
"In humans, we fail, in large part, either to detect SPMs in a manner that relates either to the dose of fish oil or to the resolution of inflammation," said Dr. Garret A. FitzGerald, of the department of Systems Pharmacology and Translational Therapeutics at the University of Pennsylvania, in a press release. "Studies with synthetic SPMs raise the possibility of their providing a structural basis for building drugs that limit inflammation. However, our results question the importance of this system in the body's own response to inflammation. In particular, we found no evidence supporting their role in mediating an anti-inflammatory action of fish oils, a putative health benefit of such supplements which itself remains to be established."
Giving synthetic supplements to healthy individuals, researchers found they couldn't detect omega-3 polyunsaturated fatty acids in blood or urine, nor did they see any chemical evidence they were present during the resolution of inflammation.
Researchers said part of the explanation for this lies in the way the body processes these oils. When people eat fish, the omega-3 polyunsaturated fatty acids are consumed as triglycerides attached to a glycerol backbone. When supplements are produced, the fatty acids are detached from the glycerol and concentrated as either ethyl-esters or triglycerides.
The human intestinal tract processes natural triglycerides differently than synthetic ones, which researchers said may be why the oils their expected effects were undetectable in the study's participants.
"We found that the clinical promise of these mediators is weak," said Dr. Carsten Skarke, McNeil Fellow in translational medicine at the University of Pennsylvania. "There are few reliable data based on such rigorous detection methods as mass spectrometry confirming that SPMs form in humans after taking fish oil pills."