Chinese language - Study finds virus contributes to obesity

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WORLD / Health

Study finds virus contributes to obesity

(AP)
Updated: 2007-08-21 10:05

WASHINGTON - In the buffet of reasons for why Americans are getting
fatter, researchers are piling more evidence on the plate for one
still-controversial cause: a virus.

New research announced Monday found that when human stem cells - the
blank slate of the cell world - were exposed to a common virus they
turned into fat cells. They didn't just change, they stored fat, too.

While this may be a guilt-free explanation for putting on pounds, it
doesn't explain all or even most of America's growing obesity problem.
But it adds to other recent evidence that blames expanding waistlines on
more than just super-sized appetites and underused muscles.

For several years, researchers have looked at a possible link between
obesity and this common virus, called adenovirus-36, from a family of
viruses that cause colds and pinkeye in people. They had already found
that a higher percentage of fat people had been infected with the virus
than nonfat people. They had exposed animals to the virus and got them to
fatten up and even found a a gene in the virus that causes animals to get
obese.

But ethical restraints kept researchers from exposing people to the virus
to see what happens. So they did what would be considered the next best
thing, said Nikhil Dhurandhar, who headed the research at the Pennington
Biomedical Research Center in the Louisiana State University system.

They took fat tissue from people who had liposuction, removed adult stem
cells from the tissue and exposed the cells to the virus in the lab.
Adult stem cells can regenerate and turn into different types of
specialized cells to help the body heal itself.

More than half the stem cells exposed to the virus turned into fat cells
and accumulated fats, while only a small percentage of the non-exposed
stem cells did the same, said researcher Dr Magdalena Pasarica, who
presented the results Monday at the American Chemical Society's annual
meeting in Boston.

"It's the first time we see an effect in human cells," Pasarica said in a
phone interview.

If a viral cause of obesity can be confirmed, a vaccine could be
developed, maybe within five to 10 years, to prevent the virus from
making some people fat, Dhurandhar said. However, it wouldn't help people
already obese, he said.

Outside experts are intrigued but worry about people blaming all obesity
on viruses, when this may be just one of many causes. It doesn't mean
it's OK to overeat, blame a bug or wait for some kind of antivirus
medicine, they said.

"The cause for obesity in everyone is the same," said Dr Samuel Klein,
director of the Center for Human Nutrition at the Washington University
School of Medicine in St. Louis. "You eat more calories than you burn up;
You can't get away from that basic law of physics."

But there are many causes that trigger overeating and extra storage of
fat in the body, including the virus, Klein said. However, he said he
considers the virus only a small factor, easily outweighed by genetics
and even childhood eating habits.

Dhurandhar said some of his earlier research found that 30 percent of
obese Americans had developed antibodies to the virus, showing they had
been exposed to it at some point. But for non-obese people, only 11
percent had antibodies, he said.

That means for some people it is not their fault they are fat, Dhurandhar
said.

But Klein said that's not completely right.

"We don't want obese people to feel that it's all their fault because it
is not all their fault ... but clearly the buck finally lies with the
person," Klein said.

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