New evidence shows an additional mechanism by which Omega-3 fatty acids (fish oils) lower inflammation possibly hindering glucose resistance early on in the process

September 08, 2010

Omega-3 fatty acids such as those found in fish oils may reduce inflammation by acting on a receptor found in fat tissue and also found on inflammatory immune cells called macrophages. Omega-3 fatty acids have been long associated with anti-inflammatory effects.

    Fish oils couple with receptors on a protein known as GPR120. Research shows that GPR120 is involved with GLP1 release which improves insulin sensitivity decreasing the risk of metabolic problems such as insulin resistance that lead to diabetes. The new research suggests the mechanisms behind omega-3’s actions as an anti-inflammatory are due to its action on GPR120 which senses the presence of the fatty acids. GPR 120 receptors are also found on large immune cells known as macrophages. "Omega-3s are very potent activators of GPR120 on macrophages - more potent than any other anti-inflammatory we've ever seen," said lead researcher Dr Jerrold Olefsky of the University of California, San Diego. In this way fish oils inhibit inflammation related to immune system activity.

     GPR120 is a G protein-coupled receptor - part of a group involved in many important cell functions, and it is the target of many drugs. Previous research has suggested that five GPCRs – including GPR120 included – respond well to free fatty acids. The researchers found that GPR120 functions as an omega-3 receptor in pro-inflammatory macrophages and mature adipocytes (fat cells; these often release chemicals that cause inflammation and heart disease).  Since chronic tissue inflammation is linked to insulin resistance in obesity, the researchers looked specifically at a root cause of inflammation.   

     They started with GPR120 knock-out mice; those lacking GPR120 activity to investigate if omega-3 leads to GPR120-mediated anti-inflammatory and insulin sensitizing effects in vivo. When the knock-out mice were fed a high-fat diet and treated with omega-3 fatty acids, they showed all the signs of inflammation and the insulin resistance that leads to diabetes with omega-3 having no effect. However normal mice on a high-fat diet supplemented with omega-3s showed the oils "had a really robust effect in preventing inflammation," Olefsky said. The study also observed that by signalling through GPR120, omega-3 fatty acids mediate potent anti-inflammatory effects to inhibit certain key inflammatory signalling pathways. The study reports that omega-3 treatment was as effective - or in some cases more effective - than the popular insulin-sensitizing drug Rosiglitazone (Avandia) used to treat diabetes. The researchers noted that activation of GPR120 by omega-3s blocks not one, but all inflammatory pathways. The study is published in the journal Cell; Volume 142(5) pp. 687 – 698.