Less TV time may lower heart disease risk, even for those with high genetic risk for diabetes
By American Heart Association News
Limiting time spent watching television to no more than one hour each day may lower the risk of heart attack, stroke and other blood vessel diseases, even among people with a high genetic risk for Type 2 diabetes, new research finds.
The study, published Wednesday in the Journal of the American Heart Association, is one of the first to investigate how genetic risk for Type 2 diabetes might interact with television viewing in relation to future atherosclerotic cardiovascular disease, which develops from plaque buildup in the arteries.
"Type 2 diabetes and a sedentary lifestyle, including prolonged sitting, are major risk factors for atherosclerotic cardiovascular disease," lead study author Dr. Youngwon Kim said in a news release. Kim is a professor in the School of Public Health at The University of Hong Kong in Pokfulam.
"Watching TV, which accounts for more than half of daily sedentary behavior, is consistently associated with an increased risk of Type 2 diabetes and atherosclerosis," Kim said. "Our study provides new insights into the roles of limiting TV viewing time in the prevention of atherosclerotic cardiovascular disease for everyone and especially in people with a high genetic predisposition for Type 2 diabetes."
Atherosclerotic cardiovascular disease, or ASCVD, includes heart disease, stroke and peripheral artery disease. It can lead to a lower quality of life, bypass surgery, stenting to open up arteries, amputations and premature death.
In the study, researchers analyzed genetic, lifestyle and medical records for 346,916 adults in a large biomedical database and research resource in the United Kingdom. Participants were an average 56 years old and were followed for nearly 14 years, during which 21,265 people developed ASCVD.
Polygenic risk scores are used to predict a person's chances of developing a disease or condition by combining information from many genetic variants. Using 138 genetic variants associated with Type 2 diabetes, researchers calculated polygenic risk scores for each study participant and then categorized them as having a low, medium or high risk for the condition. Researchers used self-reporting questionnaires to categorize the participants' TV viewing time, dividing them into those who watched TV for one hour or less and those who watched for two hours or more each day.
About 21% of participants reported watching TV for one hour or less each day. The 79% of participants who watched TV two or more hours each day had a 12% higher risk of developing ASCVD than their peers who watched less TV, regardless of their genetic risk for Type 2 diabetes. People with medium and high genetic risk for Type 2 diabetes did not have a higher risk of developing ASCVD as long as they limited their TV viewing to one hour or less each day.
But for people with a low genetic risk for Type 2 diabetes who spent at least two hours watching TV each day, their risk of developing ASCVD over the next 10 years was slightly higher than for people with a high genetic risk who limited their TV viewing to an hour or less: 2.46% compared to 2.13%, respectively.
"This suggests that less TV viewing could serve as a key behavioral target for preventing atherosclerotic cardiovascular disease linked to Type 2 diabetes genetics," study co-author Dr. Mengyao Wang of The University of Hong Kong said in the news release. To prevent disease and boost health, Wang said, future efforts should encourage people – especially those at high genetic risk for Type 2 diabetes – to spend less time in front of the TV and adopt healthier habits.
The study showed that reducing TV time might benefit people at both high and low risk for Type 2 diabetes, Dr. Damon L. Swift said in the news release. Swift is an associate professor in the department of kinesiology at the University of Virginia in Charlottesville.
"It also highlights how lifestyle choices can improve health," said Swift, who was not involved in the study. "These findings add to the evidence that sitting time may represent a potential intervention tool to improve health in people in general, and specifically for people with a high risk for Type 2 diabetes. This is especially important because people with Type 2 diabetes are at a heightened risk for cardiovascular disease compared to those who do not have diabetes."