Kang says he plans to replicate the work in cows and chickens.
Approval and Apprehension
Experts say it may be a while, if at all, before pork that is as healthy as salmon appears in supermarkets.
In the United States all genetically modified animals have to be approved by the U.S. Food and Drug Administration (FDA) before they can be sold commercially.
To date the FDA has not permitted the sale of any such animals for food. An application seeking approval of genetically engineered fish has been pending for nearly six years.
"It is too early for the FDA to have received an application from the researchers seeking approval," a spokesperson for the agency said of Kang's pigs.
Kang's research has prompted concerns from some experts about food safety and animal welfare, while others have questioned the secretive nature of the approval process.
"The application process is confidential, and the FDA needs to have a transparent process that addresses the public's moral and ethical concerns towards animal cloning," said Michael Fernandez, executive director of the Pew Initiative on Food and Biotechnology in Washington, D.C.
According to Margaret Mellon, who heads the Food and Environment Program at the Boston-based nonprofit Union of Concerned Scientists, Kang's work "raises serious questions about interfering with fatty acid metabolism."
"We don't know about the fat levels in adults and in future generations. There has been no study on the effect it might have," Mellon said.
Responding to Kang's point about declining fish stocks, Mellon added, "We need to solve the ocean crisis and not push it as an excuse for introducing genetically modified food."
Opinion on the benefits of omega-3 fatty acids is mixed as well.
A study published online this week in the British Medical Journal suggests that evidence of potential health benefits from the fatty acids may be less conclusive that had been thought.
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