Reducing TV viewing to less than 1H/day helps prevent heart disease

According to the British Heart Foundation, coronary heart disease is one of the leading causes of death, responsible for around 64,000 deaths each year. People with coronary heart disease are twice as likely to even develop a stroke.

Watching too much TV is associated with increased risk of coronary heart disease regardless of an individual's genetic makeup. In a study published in BMC Medicine, the researchers show that-assuming a causal link-11% of cases of coronary heart disease could be prevented if people watched less than an hour of TV each day.

To examine the link between time spent in screen-based sedentary behaviours such as TV viewing and leisure-time computer use, an individual's DNA, and their risk of coronary heart disease, researchers examined over 500,000 adults who have been followed up prospectively for about 12 years. The team created polygenic risk scores for each individual-that is, their genetic risk of developing coronary heart disease. As expected, individuals with higher polygenic risk scores were at greatest risk of developing the condition.

People who watched more than four hours of TV per day were at greatest risk of the disease, regardless of their polygenic risk score. Compared to these individuals, people who watched two to three hours of TV a day had a relative 6% lower rate of developing the condition, while those who watched less than an hour of TV had a relative 16% lower rate.

Therefore, the researchers concluded that limiting TV viewing might have in preventing coronary heart disease. Individuals who watch TV for less than one hour a day were less likely to develop the condition, independent of their genetic risk.