Sep. 2, 1997 DALLAS, Sept. 2 -- Children already in danger of developing heart disease because of high cholesterol blood levels face a "triple jeopardy" if they live in smoke-filled homes, according to a study appearing in today's American Heart Association journal Circulation.
The study, the first of its kind to look at blood fats and second-hand smoke in children (ages 2 to 18) with elevated cholesterol, found that passive smoke lowers by about 10 percent the level of the child's HDL. HDL, the "good" cholesterol, protects against heart attacks.
Children with an inherited cholesterol disorder already have a higher risk of developing heart disease. Exposure to second-hand smoke at an early age lowers HDL. In addition, smokers' offspring more often become smokers themselves, says Ellis J. Neufeld, M.D., Ph.D., and his colleagues at Boston Children's Hospital
Neufeld and his co-workers made a preliminary report on their research at the American Heart Association's 1994 Scientific Sessions in Dallas.
The findings suggest that escaping a smoky environment could raise children's HDL by 10 percent -- equal to, or better than other risk-reducing interventions.
"It's hard to make HDL go up 10 percent. Diet and exercise can help, but we'd predict that ending exposure to passive smoke would be at least as effective as these measures," says Neufeld, director of Clinical Hematology at Children's Hospital.
Children in the study were considered at high risk because of cholesterol abnormalities -- either total cholesterol above 200 mg/dl (considered high in children), HDL levels that were unusually low or family history of heart disease. They had been referred to a Children's Hospital clinic for treatment of their cholesterol disorders.
Twenty-seven percent of the 103 children came from households of cigarette smokers. Those exposed to tobacco had HDLs averaging 38 milligrams per deciliter (mg/dl) of blood, while HDLs averaged 43 mg/dl among those who didn't have to inhale smoke-fouled air.
There are 27.4 million young Americans under 19 with cholesterol levels above 170mg/dL (comparable to a level of 200mg/dL in adults). "So many thousands of these youngsters can conceivably benefit from removing the smoke in their environment," he says.
Passive smoke's effect was not attributable to demographic characteristics of the smoking households, knowledge of cholesterol, parents' attitudes or physiological factors, the authors add. Because all those in the study had abnormal blood cholesterol levels, the conclusions can't be applied to all children, the researchers point out. Their study's impact is limited by its relatively small size and by the fact that no tests were conducted for chemical components of tobacco smoke. Also, the investigators say their study's design did not allow them to prove that reducing passive smoke exposure would raise children's HDL levels.
The study accounted for body mass index (an indicator of obesity), age, sex, exercise and dietary fat intake.
Co-authors of today's report with Neufeld were Michele Mietus-Snyder, M.D.; Alexa S. Beiser, Ph.D., Annette L. Baker, R.N., M.S.N., and Jane W. Newburger, M.D., M.P.H.
Circulation is one of five scientific journals published by the American Heart Association, which has its national headquarters in Dallas.
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