Why Fish Oils Can Improve Diabetes Control
Olefsky and colleagues looked at cellular receptors known to respond to fatty acids. They eventually narrowed their focus to a G-protein receptor called GPR120, one of a family of signaling molecules involved in numerous cellular functions. The GPR120 receptor is found only on pro-inflammatory macrophages in mature fat cells. When the receptor is turned off, the macrophage produces inflammatory effects. But exposed to omega-3 fatty acids, specifically docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), the GPR120 receptor is activated and generates a strong anti-inflammatory effect.
Olefsky, a professor of medicine and associate dean of scientific affairs for the UC San Diego School of Medicine stated that, "It's just an incredibly potent effect… The omega-3 fatty acids switch on the receptor, killing the inflammatory response."
The scientists conducted their research using cell cultures and mice, some of the latter genetically modified to lack the GPR120 receptor. All of the mice were fed a high-fat diet with or without omega-3 fatty acid supplementation. The supplementation treatment inhibited inflammation and enhanced insulin sensitivity in ordinary obese mice, but had no effect in GPR120 knockout mice. A chemical agonist of omega-3 fatty acids produced similar results.
"This is nature at work," said Olefsky. "The receptor evolved to respond to a natural product -- omega-3 fatty acids -- so that the inflammatory process can be controlled. Our work shows how fish oils safely do this, and suggests a possible way to treating the serious problems of inflammation in obesity and in conditions like diabetes, cancer and cardiovascular disease through simple dietary supplementation."
However, Olefsky said more research is required. For example, it remains unclear how much fish oil constitutes a safe, effective dose. High consumption of fish oil has been linked to increased risk of bleeding and stroke in some people.