STUDY Sunshine is important for strong bones in children
P arents should make sure their children play outside often and spend less time in front of the television or computer, advises Ulrich Fegeler, spokesman for Germany's Professional Association of Children's and Young People's Physicians.
“Among other things, outdoor exercise is important for the production of vitamin D, which is necessary for proper bone mineral density,” he says, noting that vitamin D was a natural component of very few foods. “The body produces about 90 per cent of the vitamin with the help of sunlight on the skin.” In particular, girls aged 11 to 13 years and boys aged 14 to 17 years are believed to have a deficiency of vitamin D. British paediatricians have observed that teenagers whose mothers insist they engage in more activities outdoors spend less time in front of a TV or computer.
But those whose parents are more permissive regarding television and computer use have a five-fold greater risk of sitting in front of an electronic screen in excess of four hours daily.
Between October and March in many parts of the world, there is generally too little ultraviolet-B radiation from sunlight for the body to photosynthesise sufficient amounts of vitamin D in the skin.
A body that has stored vitamin D during the summer months, however, can draw on it for several months in the winter. Vitamin D levels are therefore usually lowest in February in several countries.
“Adolescents should enjoy the sun moderately at least three to four times a week for 15 to 30 minutes — or better, daily for at least 10 to 15 minutes,” Fegeler says. That means being outdoors with partially exposed skin. Uncovered hands, forearms and face are enough.