Some people swear smoking cigarettes keeps them slim.
But being exposed to cigarette smoke can actually make
people pile on the pounds - the surprise is that secondhand smoke is the
biggest culprit.
Innocent victims of secondhand cigarette smoke are the most
likely to gain weight, researchers found.
'For people who are in a home with a smoker, particularly
children, the increased risk of cardiovascular or metabolic problems is
massive,' said lead author Professor Benjamin Bikman, of Brigham Young
University in Utah.
Passive smoking damages the body because second-hand smoke
contains more than 4,000 chemicals, many of which are irritants and toxins, and
some of which are known to cause cancer.
Data shows half of the U.S. population is exposed at least
once daily to secondhand cigarette smoke and approximately 20 per cent of young
children live with someone who smokes in the home.
In the UK it's estimated that second-hand smoke kills over
12,000 people every year from lung cancer, heart disease, stroke and the lung
disease Chronic Obstructive Pulmonary Disease (COPD).
Professor Bikman, and his co-author Professor Paul Reynolds
wanted to investigate how cigarette smoke is tied to metabolism.
They wanted to pinpoint the mechanism behind why smokers
become insulin resistant, which leads to weight gain.
To carry out their study, they exposed mice to or
second-hand smoke and analysed their metabolic progression.
Sure enough, those exposed to smoke put on weight.
When they drilled down to the cellular level, they found the
smoke triggered a tiny lipid called ceramide to alter mitochondria in the
cells, causing disruption to normal cell function and inhibiting the cells'
ability to respond to insulin.
The lungs provide a vast interface with the environment, and
the research shows that passive smoking alters a body's sensitivity to insulin,
Professor Reynolds said.
'Once someone becomes insulin resistant, their body needs
more insulin. And any time you have insulin go up, you have fat being made in
the body.'
The key to reversing the effects of cigarette smoke, they
discovered, is to inhibit ceramide.
The researchers found the mice treated with myriocin - a
known ceramide blocker - didn't gain weight or experience metabolic problems,
regardless of their exposure to the smoke.
However, when the mice exposed to smoke were also fed a
high-sugar diet, the metabolic disruption could not be fixed.
Now Professor Bikman and his team are in a race with other
researchers to find a ceramide inhibitor that is safe for humans.
'The idea that there might be some therapy we could give to
innocent bystanders to help protect them from the consequences of being raised
in a home with a smoker is quite gratifying,' he said.
But for the smokers themselves, there is no 'protective
therapy' available.
'They just have to quit,' he said. 'Perhaps our research can
provide added motivation as they learn about the additional harmful effects to
loved ones.'
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