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Epidemic of Liver Disease Linked to Obesity

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Duke Health News 919-660-1306

One of the most serious results of overeating, a condition known as
non-alcoholic fatty liver disease (NAFLD), is on the rise, according to
gastroenterologists at Duke University Medical Center.

While
there is no confirmed cause of NAFLD, many experts believe that weight
loss and increased physical activity are good starting points to help
prevent or slow the progress of the condition. Anna Mae Diehl, chief of
gastroenterology at Duke, said that NAFLD has become much more
widespread as the obesity crisis has worsened.

"By studying over
12,000 people, we demonstrated that probably about 20 percent of people
have an elevated liver enzyme that can't be explained by anything other
than NAFLD," she said.

Despite the significant presence of NAFLD
in the U.S. population, the condition has been relatively unknown and
understudied compared to other causes of liver damage, said Diehl.

"People
are very aware of chronic hepatitis C, and we have a fairly good
estimate of that from testing volunteer blood donors in the United
States," she said. "The estimates are that somewhere around two percent
of the adult population is infected with hepatitis C. But about 20
percent of the U.S. adult population has non-alcoholic fatty liver
disease, so NAFLD would be 10 times more common than hepatitis C."

Experts
said the damage done by fat accretion in the liver is similar to that
done by excessive alcohol consumption. As the level of fat increases,
liver tissue shrinks. This can cause permanent damage to the organ
system. A liver that is more than 10 percent fat is at increased risk
for developing cirrhosis or even liver cancer.

Blood tests are
commonly the first method of diagnosing NAFLD. If the tests indicate
the presence of an elevated liver enzyme, ultrasound, CT (computed
tomography) scan or MRI (magnetic resonance imaging) is used. After a
physician has eliminated other potential causes of a liver problem,
including alcohol abuse, the diagnosis must be confirmed by a liver
biopsy, in which a needle is inserted into the liver to extract a
tissue sample, which is then analyzed.

As for risk factors, Diehl said one of the most common is obesity.

"In
people who are not particularly overweight, the risk of having NAFLD if
you have an incidentally detected abnormal blood test might only be
about 40 to 50 percent. However, if you're overweight or obese, that
risk can be as high as 90 percent. Certainly being overweight increases
the likelihood that you'll have this particular kind of liver disease.

"Many
people who are overweight don't have NAFLD," Diehl continued. "We're
trying to figure out why that is the case. It appears that there may be
some difference in where you carry your fat. People who are 'apples' –
who have a higher waist-to-hip ratio and carry most of their weight
around their middle – have what we call visceral adiposity. That seems
to be the bad kind of fat, the kind that's associated with other
complications of obesity such as having high blood pressure or type 2
diabetes or problems with cholesterol. That's the same kind of fat
that's associated with NAFLD."

As yet there is no approved
medication to treat or cure non-alcoholic fatty liver disease. Diehl
said, however, that many individuals can reduce their risk of NAFLD by
making some basic lifestyle changes.

"I think we were all praying
that there would be a pill, but the unfortunate truth is that it's
probably diet and exercise, at least as a good starting point. You may
be genetically challenged, in that you have a certain repertoire of
genes that makes you more vulnerable to develop these complications of
being overweight. If that is in fact the case, then prudence is
probably the better part of valor."

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