The mystery of how fish oil helps fight diabetes and heart disease may have been solved.
US researchers discovered how omega-3 interacts with specialised white blood cells called macrophages that surround and digest harmful molecules and cell debris.
The anti-inflammatory properties of the fatty acids in oily fish like mackerel and sardines are the key to future drugs and dietary solutions, scientists believe.
The risk of chronic conditions such as type 2 diabetes, heart disease and arthritis appear to be reduced with its use. There is also growing evidence that they combat cancer and stave off dementia.
These effects have been put down to the ability of omega-3 to control inflammation, an immune response that can get out of control.
Macrophages secrete proteins that trigger inflammation. But omega-3 was found to latch onto a switch-like "receptor" on macrophage cells and stop this happening.
When the GPR120 receptor is turned "off", the macrophage produces inflammatory effects. Omega-3 switches the receptor "on" causing a chain of biochemical events that lead to inflammation shutting down.
Professor Jerrold Olefsky, from the University of California at San Diego, said: "It's just an incredibly potent effect. The omega-3 fatty acids switch on the receptor, killing the inflammatory response."
"Previous to training as a practice nurse I worked in a local pharmacy. I repeatedly saw excellent responses to omega 3 fish oils with glucosamine in people with inflammatory joint conditions" - Teresa O'Brien, Liverpool