LONDON (Reuters) - An omega 3 fatty acid found in fish oils reduced the size of tumours in mice and made a chemotherapy drug more potent while limiting its harmful effects, Egyptian researchers reported on Thursday.

The findings, published in publisher BioMed Central's peer-reviewed Cell Division journal, add to evidence showing a range of health benefits from eating the fatty acids found in foods such as salmon.

A.M. El-Mowafy and colleagues from Mansoura University in Egypt looked at how an omega 3 fatty acid called docosahexanoic acid, or DHA, affected solid tumours growing in mice and how well it interacted with the chemotherapy drug cisplatin.

"Our results suggest a new, fruitful drug regimen in the management of solid tumours based on combining cisplatin and possibly other chemotherapeutics with DHA," El-Mowafy said in a statement.

"DHA elicited prominent chemo-preventative effects on its own, and appreciably augmented those of cisplatin as well."

In March, U.S. researchers showed that a diet high in omega 3 fatty acids -- the kind found in fish such as salmon, mackerel, herring and sardines -- protected against advanced prostate cancer even in men more at risk of the disease.

The fatty acids, also found in foods such as walnuts and leafy greens, have been shown to provide an anti-inflammatory effect and have been linked to a lower risk of heart disease.

In their study, El-Mowafy's team found that, at the molecular level, DHA reduces the accumulation of white blood cells, systemic inflammation, and a harmful condition marked by decreased antioxidant levels -- all of which have been linked to tumour growth.

Their experiment also showed that the fatty acid reduced toxicity and injury to kidney tissue caused by the chemotherapy drug, the researchers said.

(Reporting by Michael Kahn; editing by Maggie Fox and Stephen Wood)