Exposure to cigarette smoke raises teenagers' risk of metabolic syndrome, a disorder associated with excess belly fat that increases chances of heart disease, stroke and diabetes, according to a study.

Researchers said it is the first study to establish such a link in teenagers.

"The bottom line to me is: As we gear up to take on this epidemic of obesity, we cannot abandon protecting our children from secondhand smoke and smoking," said lead author Dr. Michael Weitzman, executive director of the American Academy of Pediatrics Center for Child Health Research. For the study, metabolic syndrome was defined as having at least three of five characteristics: a big waist, high blood pressure, high levels of blood fats called triglycerides, low levels of good cholesterol and evidence of insulin resistance, in which the body cannot efficiently use insulin.

In the study, published yesterday in the American Heart Association online journal Circulation, researchers found that 6 percent of 12- to 19-year-olds had metabolic syndrome and that prevalence increased with exposure to tobacco smoke.

The study found that 1 percent of those unexposed to smoke developed the syndrome, 5 percent of those exposed to secondhand smoke had the disorder and 9 percent of active smokers had it. Looking at teens who were overweight or at risk for being overweight, the effect was even more marked, with 20 percent of those exposed to secondhand smoke having the syndrome and 24 percent of smokers having it.

"What this shows is that the percentages of kids who are at risk is vastly higher if they're overweight and they're exposed to secondhand smoke, down to very low levels," Weitzman said.

-- Associated Press