Beneficial oils typically produced by fish can now be manufactured by mammals, according to a new report. Research published today in the journal Nature describes genetically modified mice that contain high levels of so-called omega-3 fatty acids, which have been shown to protect against heart disease and improve circulation.

Jing X. Kang of Massachusetts General Hospital and his colleagues inserted a gene known as fat-1 from the worm Caenorhabditis elegans into mice. Fat-1 encodes an enzyme that converts omega-6 acids--which can be produced by mammals but do not have beneficial effects--into the more favorable omega-3 acids. Tissue taken from mice with the C. elegans gene had significantly higher levels of omega-3 acids compared with that of normal animals, the team found. In addition, the creatures were healthy by all other accounts.

Farmers currently feed fish meal or other marine goods to livestock in order to increase omega-3 content in animal products, but Kang and his colleagues suggest that genetic engineering--assuming the public would accept it--may bypass this step. "The obvious followup to our finding would be to create livestock animals transgenic for fat-1 and see if their tissues also contain omega-3s," he says. "This mouse model also will be useful in studies to further investigate impact of the omega-3 omega-6 ratio in disease prevention and treatment."