http://seattlepi.nwsource.com/health/1500AP_Diet_Obesity_Microbes.html

Wednesday, December 20, 2006 · Last updated 10:13 a.m. PT

Weight may be linked to type of bacteria

By SETH BORENSTEIN
AP SCIENCE WRITER

WASHINGTON -- The size of your gut may be partly shaped by which
microbes call it home, according to new research linking obesity to
types of digestive bacteria.

Both obese mice - and people - had more of one type of bacteria and
less of another kind, according to two studies published Thursday in
the journal Nature.

A "microbial component" appears to contribute to obesity, said study
lead author Jeffrey Gordon, director of Washington University's Center
for Genome Sciences.

Obese humans and mice had a lower percentage of a family of bacteria
called Bacteroidetes and more of a type of bacteria called Firmicutes,
Gordon and his colleagues found.

The researchers aren't sure if more Firmicutes makes you fat or if
people who are obese grow more of that type of bacteria.

But growing evidence of this link gives scientists a potentially new
and still distant way of fighting obesity: Change the bacteria in the
intestines and stomach. It also may lead to a way of fighting
malnutrition in the developing world.

Nikhil Dhurandhar, a professor of infection and obesity at Louisiana
State University's Pennington Biomedical Research Center, wasn't part
of the research, but said it may change the way obesity is treated
eventually.

"We are getting more and more evidence to show that obesity isn't what
we thought it used to be," Dhurandhar said. "It isn't just (that)
you're eating too much and you're lazy."

He said the field of "infectobesity" looks at obesity with multiple
causes, including viruses and microbes. In another decade or so, the
different causes of obesity could have different treatments. The
current regimen of diet and exercise "is like treating all fevers with
one aspirin," Dhurandhar said.

In one study, Gordon and colleagues looked at what happened in mice
with changes in bacteria level. When lean mice with no germs in their
guts had larger ratios of Firmicutes transplanted, they got "twice as
fat" and took in more calories from the same amount of food than mice
with the more normal bacteria ratio, said Washington University
microbiology instructor Ruth Ley, a study co-author.

It was as if one group got far more calories from the same bowl of
Cheerios than the other, Gordon said.

In a study of dozen dieting people, the results also were dramatic.

Before dieting, about 3 percent of the gut bacteria in the obese
participants was Bacteroidetes. But after dieting, the now normal-sized
people had much higher levels of Bacteroidetes - close to 15 percent,
Gordon said.

"I think that gut bacteria affects body weight," said Virginia
Commonwealth University pathology professor Richard Atkinson, who
wasn't part of the research team and is president of Obetech Obesity
Research Center in Richmond. "I don't think there's any doubt about
that and they showed that."

The growing field of research puts more importance in the trillions of
microbes that live in our guts and elsewhere, crediting it with
everything from generations of people getting taller to increases in
diabetes and asthma.

People are born germ-free, but within days they have a gut blooming
with microbes. The microbes come from first foods - either breast milk
or formula - the exterior environment, and the way the babies are born,
said Stanford University medicine and microbiology professor David
Relman, who was not part of the study.

For decades, doctors have treated bacteria in a "warlike" manner, yet
recent research shows that "most encounters we have with microbes are
very beneficial," Gordon said.

"Much of who we are and what we can do and can't do as human beings is
directly related to microbial inhabitants," Relman said.

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I guess it never occurred to these advanced degree pinheads that a diet
high in grains, refined carbs and sugars, will tend to cause a
different gut flora than, let's say, a diet with more real food.

Do we treat the marker, ie. gut flora, or do we alter the diet to
correct the gut flora?

Soon some pharmaceutical company will come up with gut flora reseedeers
and reconditioners that will make you thin, only $299.99 for three
months worth and four pages of small print side effects.

TC