A new study from the University of Liverpool says, "too much."
"Researchers from the University of Liverpool and colleagues from Action on Sugar have assessed the sugar content of over 200 fruit drinks marketed at children and have found them to be unacceptably high.
...To assess the sugar content of fruit juice drinks, 100% natural juices, and smoothies marketed specifically to children, the researchers measured the quantity of 'free' sugars in 203 standard portion sizes of ... branded and supermarket own label products, using the pack labelling information provided.
...Almost half the products assessed contained at least a child's entire daily recommended maximum sugar intake of 19g or five teaspoons, show the findings.
...Of the research Professor Simon Capewell, said: "Increasing public awareness of the detrimental effect sugar sweetened drinks have on kids' teeth and waistlines has prompted many parents to opt for seemingly healthier fruit juice and smoothie alternatives."
The study also recommends parents dilute fruit juice with water and, whenever possible, give children a piece of fruit -- containing fiber, vitamins and minerals -- rather than offering sugary juice.