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Obesity
Increases Damaging 'Free Radical' Particles
People who are obese seem to have higher-than-normal levels
of oxidative stress, an accumulation of the cell-damaging
substances called "free radicals," according to
a new study.
This may be one reason why those who are overweight are
at greater risk for developing heart disease.
"Obesity, which has always been considered a risk factor
for heart disease and diabetes, really looks like it's related
to oxidative stress, and that may be one of the reasons
as to why obesity is bad for a person," lead author
Dr. John F. Keaney Jr. stated.
Oxidative stress, which is believed to contribute to a number
of different diseases and the aging process, is a normal
byproduct of body processes.
But Keaney cautioned that it is too soon to conclude that
obese people should take antioxidant vitamins, which counteract
free radicals.
"You can't use the study to say that people should
take antioxidants," said Keaney, who is at Boston University
School of Medicine in Massachusetts. "You have to take
it at face value and realize that more research will need
to be conducted to learn more about the relationship."
Nonetheless, Keaney added that the study "clearly shows
that obesity is associated with elevated levels of"
chemicals that are markers for oxidative stress.
Scientists have long sought to learn more about oxidative
stress, but assessing oxidative stress chemicals in the
body has been difficult. Now, a new method allows researchers
to measure levels of an oxidative stress-related chemical
in the body called 8-epi-PGF (2-alpha).
The new method now makes it possible to assess the relationship
between oxidative stress and a number of conditions, including
hardening of the arteries, high blood pressure and diabetes,
according to a report published in Arteriosclerosis, Thrombosis
and Vascular Biology: Journal of the American Heart Association.
In the study, the team of researchers wanted to understand
how much oxidative stress contributes to heart disease,
Keaney explained in an interview with Reuters Health.
Keaney's group tested urine samples of 2,828 men and women
for the presence of 8-epi-PGF (2-alpha), which indicates
the degree of oxidative stress in the body.
Previously, it was widely believed that high cholesterol
and high blood pressure were strongly associated with oxidative
stress. That was not supported by the present study, Keaney
said.
However, smoking and diabetes were related to higher levels
of oxidative stress. But "the big finding that nobody
predicted is that body mass index (a measurement which indicates
obesity) is a marker for oxidative stress," noted Keaney.
In general, the higher a person's body mass index, the higher
were their levels of 8-epi-PGF (2-alpha) and therefore the
more oxidative stress present in their body.
"Obesity is the predictor of oxidative stress, independent
of other stuff," said Keaney.
Still, Keaney pointed out that it remains to be seen how
detrimental high levels of oxidative stress are.
"We will have to wait until we see what happens to
these people with the higher levels of oxidative stress,"
he said. "We want to see if they have higher rates
of heart attack and death compared to people with lower
oxidative stress levels."
However, Keaney also noted that there is a growing body
of literature that suggests that the more oxidative stress
people have, the more likely they are to have blood-vessel
disease.
Oxidative stress, then, may be the "connector between
obesity and other disease," said Keaney. "We cannot
prove that from this study, the study just raises that possibility
and provides reasons for further investigation."
SOURCE: Arteriosclerosis, Thrombosis and Vascular Biology
2003;23:434-493.
Article
Source: Reuters Health
Article Author: N/A
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