OT - 'Myriad causes implicated in obesity boom'

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Myriad causes implicated in obesity boom

By LAURA HEATON

UPI Correspondent

WASHINGTON, Dec. 7 (UPI) -- A decision by the New York City Board of

Health to ban artificial trans fats is the latest, and perhaps most

controversial, effort to stem the obesity epidemic.

With an estimated 65 percent of Americans classified as overweight

or obese, public-health experts and government officials are working

to address the factors causing the boom.

The prevailing wisdom is that we eat too much and exercise too

little, said Bruce Blumberg, associate professor in the Department

of Developmental and Cell Biology at the University of California-

Irvine.

" Although that is certainly one of the most important factors, I

think it's starting to become apparent that it's not the only

factor, " he said at a meeting of experts in Washington on Tuesday.

The panel focused on possible origins of the epidemic that are just

beginning to be explored. For instance, initial findings from recent

scientific studies suggest that chemicals in the environment and

genetics play significant roles in the obesity spike.

" Despite the fact that we have unprecedented public awareness of the

problem, Americans are getting fatter and fatter all the time, "

Blumberg said.

Blumberg's research examines how characteristics of the modern

world, beyond the obvious influences -- such as the tendency toward

more sedentary lifestyles and the prevalence of high-calorie food --

may have spurred the obesity epidemic. For instance, research

conducted at UC-Irvine relates the use of a variety of industrial

chemicals to rising rates of obesity.

" You can graph the use of chemicals after the Second World War

against the incidence of obesity, and by and large there's an

association between those two, " Blumberg said. However, whether or

not there is a causal link is yet to be proven, Blumberg

acknowledged.

Blumberg cited in vitro studies that suggest a link between

environmental chemical exposure and obesity. It has been clearly

documented that children of mothers who smoke while they are

pregnant have lower birth weight and a higher tendency toward

obesity later in life, Blumberg said.

Environmental chemicals, either in the womb or in everyday life,

could inappropriately regulate metabolism, Blumberg said. Humans are

exposed to these harmful chemicals, called organotins, through

contaminated foods such as seafood and shellfish and crops treated

with fungicides, and through anti-fungal agents in wood treatments,

industrial water systems, textiles and PVC plastics.

The role of environmental chemicals in the development of complex

diseases such as obesity is just beginning to be explored. The

findings will undoubtedly lead to further investigation into

environmental influences on human health, particularly as they

relate to the obesity epidemic.

Research also gives credence to the idea that genetics may help

explain the rising number of overweight and obese individuals.

Obesity is one of the most heritable types of complex traits, said

Christman, chair of the Genetics and Genomics Department at

Boston University School of Medicine.

A team of scientists led by Christman recently analyzed a whole-

genome scan of DNA samples and identified a common genetic variant

associated with obesity. They replicated their findings in groups

composed of samples from adults and children of diverse ancestry.

The report, published in Science journal in April 2006, concludes

this obesity-prone genotype is present in 10 percent of individuals.

Christman emphasized, however, that a genetic predisposition to

obesity would not be the lone factor that determines whether an

individual is overweight or obese. Genetics determine a high and a

low point in the range of a person's weight, Christman said.

Behavior determines the person's actual weight in that range.

" For this reason, the genetic variant that predisposes individuals

to obesity was neutral in early human societies because food was not

so readily available and lifestyle required people to be more

active, " Christman said.

Christman said that he is confident that this latest research, and

the potential for further examination that it raises, will lead to

advances in treatment of medical conditions such as obesity.

" The payoff for medicine will be that (genetic testing) will

identify those biochemical pathways in the human body that really

affect the property being studied, in this case obesity, " Christman

told United Press International. " Pharmaceutical industry can then

make a better drug to target those pathways. "

The obesity discussion should also be redirected away from blaming

the victim, panelists said.

" Behavior can lead to lots of different complex diseases, but

genetics sets the boundaries, " Christman said. " Therefore, obesity

shouldn't be thought of as a moral failure on the part of obese

people, but rather a medical condition. "