Children who watch too much TV risk blood-vessel damage
Published 21/04/2011 | 05:00
TOO much TV and not enough exercise is causing early artery damage in children as young as six, according to new research.
Scientists have found that youngsters who spent most of their time watching television had narrowed blood vessels in their eyes.
The effect is a known warning sign of an increased risk of heart disease.
Researchers measured tiny differences in the size of micro-arteries at the back of the eye. Sedentary six and seven-year-olds had an average "retinal arteriolar" narrowing of 2.3 microns. A micron is one thousandth of a millimetre.
Those who regularly participated in outdoor physical activity had retinal blood vessels that were 2.2 microns wider than those who did the least exercise.
The narrowing associated with each extra hour of TV or computer viewing was similar to that which accompanies a blood pressure increase in children of 10 millimetres of mercury.
Lead researcher, Dr Bamini Gopinath, from the Centre for Vision Research at the University of Sydney, Australia, said: "We found that children with a high level of physical activity had a more beneficial microvascular profile compared to those with the lowest levels of physical activity.
"This suggests that unhealthy lifestyle factors may influence microcirculation early in life and increase the risk of cardiovascular disease and hypertension (high blood pressure) later in life."
Retinal blood vessel diameter predicts heart disease in adults, but this is the first time it has been shown to be affected by a sedentary lifestyle in young children.
"Excessive screen time leads to less physical activity, unhealthy dietary habits and weight gain," said Dr Gopinath.
"Replacing one hour a day of screen time with physical activity could be effective.
"Free play should be promoted and schools should have a mandatory two hours a week in physical activity for children," she added.