Parents are grateful when their child walks around sipping fruit juice. “Thank god, he is into that and not soft drinks,” they tell themselves. Of course, fruit juice is more healthy when compared to Coke or Pepsi.

The health food image of fruit juice is so powerful that some parents even top-up their infant feeds with it. Parents pack their children off to the playground with a water bottle full of juice; infants go to sleep sucking fruit juice from a milk bottle; and juice is the preferred fluid-replacement drink for a child with diarrhoea.

All this fruit juice worship has paediatricians worried.

First, the good stuff about juice: it is mostly water, natural fruit sugars, potassium, Vitamin A, Vitamin C and some calcium. All these are important nutrients for a growing child.

Vitamin C increases iron absorption by twofold — valuable in a predominantly vegetarian diet with low bioavailability of iron. The flavonoids in juice may have long-term health benefits, such as lowering the risk of cancer and heart disease.

Fruit juice is also convenient: international brands contain 100 per cent pasteurised and microbe-free juice.

For those who think cartons are, um, un-natural, making your own stuff by grinding up a few fruit is always an option. According to the food guide pyramid, half the daily serving of fruit can be in the form of juice.

This means that a four-year-old can safely drink 200 ml daily. An eighteen-year-old can drink up to 360 ml per day. Safe juice is pasteurised, from a carton and not the stuff made with unclean hands and lovingly mixed with roadside dust and microbes. Adding water to concentrate is an inferior option to 100 per cent natural juice. As for the stuff with added sugar and artificial flavours, forget it — even if it is “pulpy”.

What will surprise quite a few parents is this notion of an upper limit to drinking juice. Over consumption can cause dental caries, mal-absorption, diarrhoea, obesity and malnutrition. Fruit juice is not an alternative to water, milk or solid food.