http://www.timesonline.co.uk/article/0,,2-2105400,00.html
Why the the fat from this little piggy could be good for us
By Mark Henderson, Science Correspondent
A HEALTHY form of bacon, ham and even pork scratchings could soon be
available after the cloning of pigs genetically modified to produce
beneficial fats.
The piglets have been enhanced with a gene from a nematode worm to give
their meat up to five times the normal level of omega 3 fatty acids. A
diet rich in these fats, usually found in fish and vegetable oils, has
been linked to improved brain function and a lower risk of heart
disease and stroke, suggesting that the pigs' meat could be sold as a
healthier option.
The pigs - three of which were named Salmon, Tuna and Trout after
fish high in omega 3 fats - are the first cloned livestock that can
make the beneficial compounds. The success, by a research team in the
US, paves the way for a new era of animal breeding, in which animals
are genetically engineered to make their meat healthier.
While GM and cloned meat is not approved for human consumption in the
US or Britain, scientists are working on chicken, beef and fish with
enhanced omega 3 fat content. Jing Kang, of Harvard University, said:
"I think we will be eating transgenic animals in the near future.
Livestock with a healthy ratio of omega 3 to omega 6 fatty acids may be
a promising way to rebalance the diet without relying on diminishing
fish supplies or supplements."
Meat is generally low in omega 3 fatty acids and high in omega 6 fatty
acids, which do not have the same healthy properties. Fish such as
salmon and tuna are omega 3 rich, but some scientists are concerned
about people eating a lot of such fish because they contain toxic heavy
metals such as mercury, and because of the pressure on collapsing fish
stocks.
While the beneficial effects of omega 3 fats were challenged in a study
published last week, the Food Standards Agency recommends that people
eat at least a portion of oily fish and a portion of white fish every
week.
The new research, which will be published in the journal Nature
Biotechnology, suggests that GM pork could be another option. "While
fish is one of the best food sources of omega 3 fatty acids, we have
been warned to limit consumption because of high mercury levels," said
Yifan Dai of the University of Pittsburgh, the study's lead author.
"These animals could represent an alternative source."
In the study, a group led by Dr Dai, Dr Kang and Professor Randall
Prather of the University of Minnesota, genetically modified pig cells
to express a gene called fat-1, which is normally found in the nematode
worm Caenorhabditis elegans, and which converts omega 6 fats into omega
3.
They then cloned embryos from the transgenic pig cells, producing ten
male piglets. Of these, six tested positive for the fat-1 gene, and
three - Salmon, Tuna and Trout - also had between four and five
times the normal level of omega 3 fatty acids in their bodies.
Though two of these three had to be put down because of a heart
abnormality - probably a side-effect of the cloning process - a
further litter of eight was later cloned from Salmon, the pig with the
best omega 3 profile. All of these pigs were healthy, and had the
enhanced omega 3 content.
Dr Kang said that in the longer run, it would not be necessary to clone
pigs. Once a founder population had been established, these could be
used to breed in the normal way.
As well as their potential for producing healthier meat, the GM animals
have value as laboratory models for investigating the effects of omega
3 fatty acids on heart function.
"Pigs and human beings have a similar physiology," Professor Prather
said. "We could use these animals as a model to see what happens to
heart health if we increase the omega 3 levels in the body. It could
allow us to see how that helps the heart.
"If these animals are put into the food chain, there could be other
benefits. First, the pigs could have better cardiovascular function and
therefore live longer, which would limit livestock loss for farmers.
Second, they could be healthier for human consumption."