Children should be limited to just one glass of fruit juice a day, health chiefs have warned.
They say sugar is the single biggest threat to the well-being of children aged between four and 18 – and despite its healthy image, fruit juice - as well as fizzy drinks - is the biggest culprits.
Now the country's most senior nutritionist has advised limiting children - and adults - to 150ml of fruit juice per day, and always accompanied by a meal.
It is the first time health officials have outlined such a limit.
Dr Alison Tedstone, the chief nutritionist at Public Health England, part of the NHS, said: "The best drinks for school-aged children are water and low-fat milk.
"Fruit juice is also a good choice as it can be included as one of your five portions of fruit and vegetables per day.
"However, it should only be drunk once a day and with a meal because it can be high in sugar and can cause tooth decay."
Some fruit juices and smoothies contain four times as much sugar as is recommended by the World Health Organisation.
Dr Tedstone said the survey demonstrated the need for a change in habits, particularly for children and teenagers.
It found that every age group exceeded the recommendation that added sugar should be no more than 11 per cent of daily calorie intake.
Among children under 10, added sugar made up an average of 14.7 per cent of their intake, while for those aged 11 to 18 it constituted 15.6 per cent. Among adults, the figure was 12.1 per cent.
For boys under 10, fruit juice accounted for 15 per cent of their daily added sugar and other drinks a further 17 per cent.
For girls the same age, fruit juice accounted for 12 per cent and other drinks 16 per cent of added sugar.
As children got older, the proportion of sugar from soft drinks including juice rose - to 42 per cent for boys, and 38 per cent for girls.
Cereals and cereal bars were the next biggest contributors.
Health officials said they were particularly concerned about fruit juice, because many people believed it to be healthier than it is.