Remember when your mother used to have to force-feed you cod liver oil? It seems mother really does know best. Over the past decade, scientists have discovered that the omega-3 fatty acids found in fish oils help reduce inflammation, but they didn't know how. Now new research has finally unlocked the secret of how this essential fatty acid works – and the findings have broad benefits for everyone, but especially people who are obese.
Researchers at the University of California, San Diego School of Medicine have identified the molecular mechanism that makes omega-3 fatty acids reduce chronic inflammation and curb insulin resistance in cells.
It all revolves around a type of white blood cell called a macrophage. Macrophages gobble up and digest cell debris and pathogens, such as viruses and bacteria, and there are a lot of macrophages in obese fat tissue. But when macrophages do their work, they produce proteins that cause inflammation in surrounding cells. Cytokines, one of the proteins produced by macrophages, also increase insulin resistance, which can lead to type 2 diabetes mellitus.
But this new research, which was published in the September 3 issue of the journal Cell, demonstrates that omega-3 fatty acids – in particular DHA and EPA, commonly found in fish oil – activate a key receptor (GPR120) on macrophages, producing an anti-inflammatory effect and improving overall insulin sensitivity. In essence, they reverse the problems created by the abundance of macrophages.
"It's just an incredibly potent effect. The omega-3 fatty acids switch on the receptor, killing the inflammatory response," Dr. Dr. Jerrold Olefsky, a professor of medicine and associate dean of scientific affairs for the U.C. San Diego School of Medicine, said in a press release.
The natural effect has widespread implications for dealing with all health issues in which inflammation plays a role.
"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."
Olefsky cautions that more research is needed, particularly in regard to safe dosage of fish oil, since high doses have been linked to risk of stroke and bleeding because it has a blood-thinning effect. But Olefsky also said knowing which receptor needs to be activated allows researchers to look at developing drugs that have the same effect as fish oil, which could prove useful in the event that dangerously high doses of fish oil would be required to see benefits.
In the mean time, moderate DHA and EPA consumption can help you support overall good health. DHA and EPA play a key role in the development of the central nervous system, and DHA is also found in the human retina, so it may play a role in healthy vision.
Eating foods rich in DHA and EPA is the first step, but don't be misled by foods fortified with omega-3 – most contain just a fraction of what you need on a daily basis. Salmon, anchovies, mackerel, herring, cod, and other coldwater fish have the highest levels of DHA and EPA, but you'd have to eat fish several times a week, and toxins such as mercury are a real concern. Most people can eat fish a couple of times a week and take 1,000 to 1,600 milligrams of a combined DHA/EPA supplement on days fish isn't eaten. And if you don't care for fish, just stick to the supplements.
