Mmmm ... Healthy Bacon

By Rhitu Chatterjee
ScienceNOW Daily News
27 March 2006

Move over bacon, now there's something healthier. A team of researchers has created a transgenic pig that produces higher-than-normal levels of beneficial omega-3 fatty acids. This could make pork a good alternative to fish for cardiovascular health, as well as provide a model system for studying the effects of these fatty acids on human diseases.

Omega-3, or n-3, fatty acids are a group of polyunsaturated fatty acids (PUFA), well known for their benefits to human health. Fish are the richest source of n-3 fatty acids, but the potential for mercury contamination makes eating some fish products risky. Researchers have tried to enhance the content of grains, but livestock have not been a viable alternative so far. Pigs, cows, and other farm animals contain low levels of n-3 fatty acids and high levels of another group of PUFAs called omega-6, or n-6, fatty acids. And that, in fact, is a problem: This high n-6/n-3 ratio is known to contribute to the incidence of diseases such as cancer, diabetes, arthritis, and depression in humans.

Now, researchers have found a way to improve this ratio. The trick was inserting a gene from the Caenorhabditis elegans worm into the pig genome. The gene, called fat-1, codes for an enzyme that converts n-6 to n-3. A team led by Yifan Dai of the University of Pittsburgh in Pennsylvania popped the gene into the DNA in pig fibroblast nuclei and transferred these fibroblast nuclei into pig oocytes. One more set of nuclear transfers later, and the team got eight transgenic piglets. The pigs produce 3 times more n-3 fatty acids and 23% less n-6 fatty acids than normal pigs, giving the new breed a 5-fold lower n-6/n-3 ratio, the researchers reported online yesterday in Nature Biotechnology.

"I just think it's a great technical achievement," says Michael Roberts, a bovine reproductive biologist at the University of Missouri (UM), Columbia, who was not associated with this study. He cautions, however, that further studies on the quality and safety of the meat, as well as the health of the cloned animals, will need to be done before people can buy heart-healthy bacon at their local supermarket. "It's going to be a long time before such animals are able to enter the food chain," he says.

For now, co-author Randy Prather of UM, says these transgenic pigs could serve as good models for studying the effects of higher n-3 fatty acid levels on cardiovascular and autoimmune diseases. Researchers may be able to determine, for example, if higher levels of n-3 fatty acids could override the harmful effects of high fat diet on the cardiovascular fitness of the pigs, he says.