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TV raises heart risk to children as young as six

Too much TV and not enough exercise is causing early artery damage in children as young as six, a study has found.

Scientists discovered that youngsters who spent the most 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 (mmHG).

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. A total of 1,492 children from Sydney took part in the study, reported in the American Heart Association journal Arteriosclerosis, Thrombosis and Vascular Biology.

Parents answered a questionnaire detailing the amount of time their children spent watching TV, playing video games, reading, and engaging in indoor and outdoor physical activity.

Scientists took digital photographs of the blood vessels at the back of each child's eye and calculated their size. They also measured height, weight, body mass index and blood pressure.

On average, children spent 1.9 hours per day watching screens and 36 minutes per day in total physical activity.

Those who were active for just over an hour or more each day had significantly wider retinal arteries than those exercising for half an hour or less.

Dr Gopinath called for schools to have a mandatory two hours a week in physical activity for children.