Couch potatoes at higher risk of coronary heart disease, study finds | Heart disease
More than one in 10 cases of coronary heart disease could be prevented if people reduced their TV viewing to less than an hour a day, research suggests.
Coronary heart disease occurs when fatty material builds up inside the coronary arteries causing them to narrow, reducing the heart’s blood supply. Researchers say cutting down on time spent in front of the TV could lower the risk of developing the disease.
“Reducing time spent watching TV should be recognised as a key behavioural target for prevention of coronary heart disease, irrespective of genetic susceptibility and traditional risk markers,” said Dr Youngwon Kim, an assistant professor at the University of Hong Kong and an author of the research.
While the team did not look at what was behind the association, Kim said previous studies had found excessive TV viewing time is associated with adverse levels of cholesterol and glucose in the body.
“Unfavourable levels of these cardiometabolic risk markers may then lead to increased risk of developing coronary heart disease,” he said.
Writing in the journal BMC Medicine, Kim and colleagues report how they used data from 373,026 white British people aged 40-69 who were part of an endeavour known as the UK Biobank study.
None of the participants in the team’s study had coronary heart disease or stroke when recruited to the UK Biobank. However, the researchers found 9,185 cases of the disease in participants through national death registry and hospital admission records up to autumn 2021.
The study suggests that – after taking into account the genetic risk of coronary heart disease, calculated for each participant, as well as factors including body mass index, age, sex, smoking status, diet, amount of physical activity and level of deprivation – the greater the amount of TV watched, the greater the risk of developing coronary heart disease.
Compared with people who watched four or more hours of TV a day, those who watched an hour or less had a 16% lower risk of developing coronary heart disease, while for those who watched two to three hours a day the risk was 6% lower.
The researchers say the trend held across all ages and all levels of genetic risk – although those with a higher genetic risk of coronary heart disease had a greater risk of developing the condition.
However no link was found between the amount of leisure-time computer use and the risk of coronary heart disease, possible down to factors such as greater reliability in recalling TV viewing, snacking while watching TV, or TV watching tending to be more prolonged and uninterrupted.
Assuming the TV watching is driving the rise in coronary heart disease risk – a link the study cannot prove – the team estimate about 11% of coronary heart disease cases could be prevented if people cut their TV watching to less than an hour a day, even after accounting for genetic risk and other factors.
Naveed Sattar, a professor of metabolic medicine at the University of Glasgow who was not involved in the work, noted the findings may overestimate the benefits of cutting TV time on heart disease risks.
But he said: “There is abundant other evidence that increasing activity time by replacing time spent sitting helps lower body fat levels and prevents weight gain, improves blood pressure and blood fat levels, and lowers diabetes risks. All such improvements, in turn, are known to lessen heart attack and stroke risks.”