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.
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 it is too soon to conclude that obese people should take antioxidant vitamins, which counteract free radicals.
Nonetheless, the Boston investigators say 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.
In the study, the team of researchers wanted to understand how much oxidative stress contributes to heart disease. The team 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.
However, smoking and diabetes were related to higher levels of oxidative stress. But the finding that nobody predicted is that body mass index (a measurement which indicates obesity) is a marker for oxidative stress. 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.
"We will have to wait until we see what happens to these people with the higher levels of oxidative stress," the researchers said. "We want to see if they have higher rates of heart attack and death compared to people with lower oxidative stress levels."
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.
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