Study leader Janice Kiecolt-Glaser of the Institute for Behavioral Medicine Research Ohio State University School of Medicine said study participants, either overweight or obese, were given supplements in different doses, while some got placebos.
The study, published in the journal Brain, Behavior and Immunity, found both higher and lower omega-3 doses helped reduce inflammation.
"If you can't have fish that frequently or you're not that fond of it, the supplements clearly have benefits for your immune response," Kiecolt-Glaser said in a statement.
Anyone can experience inflammation, but research at the National Institutes of Health showed it could be more a problem in the presence of excess body fat, Kiecolt-Glaser said.
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