"There's no question this paper draws attention to the number of studies now that all seem to show the same thing," said Dr. Martin Abrahamson, chief medical officer of the Joslin Diabetes Center in Boston. "There are always limitations to these meta-analyses, but I think they're telling us a message we need to take heed of."
Based on disease incidence in the United States, Hu and his colleague, Anders Grontved, estimated that each two-hour increment of TV watching each day was linked to an absolute risk of 176 new cases of type 2 diabetes, 38 new cases of fatal cardiovascular disease and 104 new cases of all-cause mortality among 100,000 people per year.
Abrahamson and Hu agreed that the particularly ominous influence that TV has on diabetes incidence is due largely to its link to obesity, one of the biggest contributors to diabetes.
They also said that those who spend several hours per day exercising may be able to offset the negative health effects of prolonged TV watching, but that few tend to split their time equally between the two disparate activities.
"Certainly any physical activity would be beneficial regardless of the amount of TV you watch," Hu said. "But the reality is that people spend almost five hours a day watching TV. How much exercise do they do? There is a huge imbalance."
The Nemours Foundation has more on the health effects of TV viewing among children.
SOURCES: Frank B. Hu, M.D., Ph.D., professor, nutrition and epi
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