Researchers have found a mechanism by which omega-3 fatty acids inhibit the growth and spread of prostate cancer cells, paving the way for more effective anti-cancer drugs.
Scientists have long known that omega-3s reduce inflammation and have anti-diabetic effects and some recently discovered how this happens.
"But we are the first to show that they work this way in cancer," said Kathryn Meier, professor of pharmacy at Washington State University Spokane in a paper published in the Journal of Pharmacology and Experimental Therapeutics.
"We were the first to show this mechanism in any cancer cell at all. And we are using prostate cancer, which is the most controversial subject in omega-3s," she added.
A 2013 study in the Journal of the National Cancer Institute had found that men with higher levels of omega-3 fatty acids in their blood had a greater risk of developing prostate cancer.
It was not clear if the fatty acids came from food - certain fish, seeds and nuts are high in omega-3s - or supplements like fish oil.
Working with prostate cell cultures, Meier and his team found the fatty acids bind to a receptor called FFA4 (free fatty acid receptor 4).
Rather than stimulating cancer cells, the receptor acts as a signal to inhibit growth factors, suppressing proliferation of cancer cells.
"This kind of knowledge could lead us to better treat or prevent cancer because now we know how it works," Meier said.
The study also found that a drug mimicking the action of omega-3s can work as well or better than fatty acids in suppressing cancer cells.
According to Meier, it is still unclear if the effect can be obtained by taking dietary supplements like fish oil.
Some people do not tolerate fish oil very well.
Moreover, the effect of fish oil could fade as it is digested while data from this study suggests that an omega-3 drug needs to be in a cancer cell all the time to have an effect.