By Cassandra Willyard
Sep. 2, 2010
Pass the bass, please. Omega-3 fatty acids, a main component of fish oil, have a reputation as potent anti-inflammatory agents. Now researchers think they know how the acids block this immune response. They've also found that omega-3s can help fight diabetes in obese mice, pointing the way to potential therapies in humans.
To understand how omega-3s curb inflammation, Jerrold Olefsky, an endocrinologist at the University of California, San Diego, and his colleagues trawled through the data on a family of proteins called G protein-coupled receptors, which can bind to a number of different fatty acids. One of these receptors—GPR120—"jumped right out," Olefsky says. Olefsky's group found it on immune cells involved in inflammation, as well as in mature fat cells, and they noted that it seemed to bind to omega-3s.
To confirm the link, the team doused GPR120-containing mouse immune cells with omega-3 fatty acids. That "shut down almost all of the inflammatory pathways," Olefsky says. "It was a very powerful effect."
The researchers also genetically modified mice to lack the GPR120 receptor. They then fed the mutant mice and normal mice a high-fat diet. Both groups became obese and developed a mouse form of diabetes. Scientists have long suspected a link between inflammation and obesity-linked diabetes; and indeed, when Olefsky's team supplemented the fatty diet with a hefty helping of omega-3 fatty acids—enough to double the concentration of omega-3 in the mice's blood—the normal mice experienced a reduction in their diabetic symptoms. The rodents remained obese, but they regained some sensitivity to insulin, meaning they didn't need as much insulin to take up glucose and burn it to produce energy. In fact, the supplemented diet worked as well to combat insulin resistance as the common diabetes drug Avandia, the team reports in the 3 September issue of Cell. The mutant mice remained diabetic regardless of how many omega-3s they consumed, highlighting the importance of the GPR120 receptor.
