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Scientists Create Mice That Produce Heart-Healthy Compounds

Finding could lead to farm animals that yield the omega-3 fatty acids

WEDNESDAY, Feb. 4, 2004 (HealthDayNews) -- Scientists may have devised a way to give mammals the ability to produce heart-healthy omega-3 fatty acids on their own.

While the discovery has so far only been applied to mice, if it were transferred to farm animals, humans could one day be eating eggs, milk and meat fortified with these acids.

"The actual translation of this mouse model to what could be available to humans remains to be established, but the principle of enriching the diet is one most of us in the cardiology world would endorse," says Dr. Ronald M. Krauss, a spokesman for the American Heart Association and director of atherosclerosis research at Children's Hospital Oakland Research Institute in California.

Omega-3 fatty acids are known to prevent heart disease in humans but are only produced by microorganisms such as bacteria and algae. Humans get most of their omega-3 supply from fish.

"Fish get them from microorganisms [algae] and then we get them from fish," explains Dr. Jing X. Kang, lead author of a study appearing in the Feb. 5 issue of Nature and an associate professor of medicine at Harvard Medical School. "That's the food chain."

The American Heart Association recommends eating fish twice a week to get the requisite supply of omega-3 acids. Salmon and trout have particularly high amounts of these acids.

Many farmed fish and livestock are fed special meals to make sure they get these compounds, but this method is expensive and recent research has found that farm-raised salmon have high levels of the chemical contaminant PCB. One way around these issues might be to engineer farm animals to produce omega-3 on their own.

Paradoxically, while mammals, including humans, have a paucity of omega-3 fatty acids, they also have an abundance of omega-6 fatty acids -- or polyunsaturated fats -- that do not have health benefits.

"On the one hand, we have too much omega-6 and, on the other, too little omega-3. Can we convert to the other? That's the question," Kang says.

Kang and his colleagues reasoned that if they could transfer a gene from one of those microorganisms into a mammal, they might solve this human nutrition problem.

To this end, they transferred a gene from a roundworm, which can produce omega-3 oils on its own, into laboratory mice. The gene codes for an enzyme that converts omega-6 acids into omega-3 acids.

The mice appeared to stay healthy even in the absence of omega-3 from dietary sources. Their tissue was also high in omega-3 acids.

By contrast, wild mice who received an identical diet were deficient in omega-3 fatty acids.

The next question is whether scientists can do this in farm animals, to produce meat, milk and eggs rich in omega-3 fatty acids.

"Now that we have had the success in the mice, then we are confident that we can do this in livestock, and that's what we really want to do," Kang says. "That's the application of this technology in the future. We're trying to do this in fish."

However, the real obstacle may not be technology but public and political opinion.

"We are not worried about the technical part. We can do that in the near future," Kang says. "Politics and public opinion, that's the part we cannot control."

Still, Kang is optimistic.

"I think that this option is easier for the public to accept than any other genetically modified food because it increases their nutrients," he says. "It is unlike other methods that try to increase productivity or disease resistance. The overall chance looks good."

More information

For more on omega-3 fatty acids, visit the American Heart Association. The National Heart, Lung, and Blood Institute has heart-healthy recipes.

SOURCES: Jing X. Kang, M.D., Ph.D., associate professor,r medicine, Harvard Medical School, Boston; Ronald M. Krauss, M.D., spokesman, American Heart Association, and director, atherosclerosis research, Children's Hospital Oakland Research Institute, California; Feb. 5, 2004, Nature
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