TV Viewing Linked to Higher Risk of Type 2 Diabetes, Cardiovascular Disease & Death

By Editor, on June 19th, 2011

A new study has found a correlation between every two additional hours of television viewing per day and an increase in risk of type 2 diabetes, cardiovascular disease, and death.

The study, by researchers from Harvard School of Public Health, Harvard Medical School, and the Institute of Sport Science and Clinical Biomechanics, University of Southern Denmark, was published in the June 15, 2011 issue of JAMA, the Journal of the American Medical Association.

In an introduction to their study, lead authors, Anders Grøntved, MPH, MSc visiting Scholar at the Harvard School of Public Health from the University of Southern Denmark, and Frank B. Hu, MD, PhD, of Harvard Medical School and Harvard School of Public Health, stated that “Television (TV) viewing is the most commonly reported daily activity apart from working and sleeping in many populations around the world.”

In the U.S., the authors explained, according to recent reports, people watch an average of 5 hours of television daily, while in several European countries and Australia the average TV viewing time is 3.5 to 4.0 hours per day.

In the study, the researchers performed a meta-analysis of eight previous scientific studies conducted from 1970 through 2011, that measured and found links between TV viewing and risks of type 2 diabetes, cardiovascular disease, and/or death.

Altogether, the studies they analyzed that reported results on type 2 diabetes included 175,938 individual study subjects, and 6428 incident cases during 1.1 million person-years of follow-up. Those that reported on fatal or nonfatal cardiovascular disease, included 34,253 individuals, and 1052 incident cases. And, those that reported on all-cause mortality, included 26,509 individuals, and 1879 deaths during 202,353 person-years of follow-up.

As a result of their analysis, the researchers found that among the relevant study populations, for every two additional hours of TV watching per day, the risk of type 2 diabetes increased by 20%, and the risk of fatal or nonfatal cardiovascular disease increased by 15%. In the studies measuring all-cause mortality, after three hours of TV watching per day, the risk of death from any cause increased by 13% for each additional two hours of TV watching per day.

“Based on incidence rates in the United States,” the authors state, “we estimated that the absolute risk difference (cases per 100,000 individuals per year) per 2 hours of TV viewing per day was 176 for type 2 diabetes, 38 for fatal cardiovascular disease, and 104 for all-cause mortality.” In other words, for every 2 additional hours of TV viewing, out of 100,000 people, 176 additional persons would get type 2 diabetes, 38 more would suffer fatal cardiovascular disease, and 104 more would die from any or all causes.

In potential explanation of the associations found in the studies, the authors observed:

“Beyond altering energy expenditure by displacing time spent on physical activities, TV viewing is associated with unhealthy eating (eg, higher intake of fried foods, processed meat, and sugar-sweetened beverages and lower intake of fruits, vegetables, and whole grains) in both children and adults. Furthermore, TV viewing may be associated with the intake of foods and beverages that are advertised on TV and could attract some individuals to begin smoking.”

“Physical inactivity, various dietary factors, and smoking are well established independent risk factors of type 2 diabetes, cardiovascular disease, and all-cause mortality.”

In conclusion, the authors wrote, “findings from this meta-analysis of prospective studies suggest that longer duration of TV viewing time is consistently associated with higher risk of type 2 diabetes, fatal or nonfatal cardiovascular disease, and all-cause mortality.”

“The message is simple,” senior author Frank Hu told Science Daily. “Cutting back on TV watching can significantly reduce risk of type 2 diabetes, heart disease, and premature mortality,” he said. “We should not only promote increasing physical activity levels but also reduce sedentary behaviors, especially prolonged TV watching,” Hu concluded.

In their study report, the authors also called for “additional research quantifying the mediating influence of diet and physical inactivity.” And, they wrote, “Future research also should assess the association of prolonged daily use of new media devices on energy balance and chronic disease risk.”

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