THURSDAY, July 15, 2004 (HealthDayNews) -- Children who watch television for more than two hours a day go into their adult years ripe with the risk factors that make them likely candidates for heart attack, stroke and other cardiovascular problems, New Zealand researchers report.
Other studies have linked zealous television viewing by youngsters with several health problems, mental and physical. This one is unusual because it followed more than 1,000 children for more than two decades, from age 3 to age 26.
A clear association was found between watching television more than two hours a day in the early years and overweight, high cholesterol levels, smoking and poor physical condition a decade or more later, said a report in July 17 issue of The Lancet by researchers at the University of Otago in New Zealand.
An analysis found that "17 percent of overweight, 15 percent of raised serum cholesterol, 17 percent of smoking, and 15 percent of poor fitness can be attributed to watching television for more than two hours a day during childhood and adolescence," the researchers reported.
"We concur with the American Academy of Pediatrics that parents should limit children's viewing to one to two hours a day," said a statement by Dr. Robert J. Hancox, leader of the research team. "In fact, data suggest that less than one hour a day would be even better."
The two-hour-a-day cutoff is more or less arbitrary, said Dr. Dimitri A. Christakis, a pediatrician at Children's Hospital and Regional Medical Center in Seattle, who has done research on a different aspect of TV watching: its effect on children's minds.
That study found an association between time spent watching television at age 3 and an increased incidence of attention-deficit disorder at age 7. "In our study, it appeared that it was the rapid pace of imaging that was damaging to the brain," Christakis said.
It is important for parents to be attentive not only to the amount of time a child spends in front of a television set, but also to the content of programs the child watches, he said.
Studies have linked a tendency to violent behavior to the amount of violence seen in television programs, Christakis said. And there can be more subtle effects, he said.
"Cigarette smoking is an example," Christakis said. "Many TV shows portray cigarette smoking in a way that makes it seem sexy or attractive."
Despite the potential dangers, "most parents aren't really aware of what their children are watching," he said. "Thirty percent of children in the United States have TVs in their bedroom, so the amount and content of viewing are not supervised by the parents."
The New Zealand study is gives "more evidence of the potential harm associated with television viewing in children and evidence that more studies are needed about the effect of television viewing on children," Christakis said.
A parent's guide to what television can do to children and what they can do about it can be found at the American Academy of Pediatrics.