Some juice drinks aimed at children contain more sugar than Coca Cola, experts have warned.

They carried out a survey of 203 fruit juices, juice drinks and smoothies being sold in UK supermarkets and found that at least 25% contained the same amount or more sugar than Coca Cola, which contains five teaspoons of sugar per 200ml glass.

The survey was carried out by Action on Sugar, an international group of healthcare specialists who are concerned about sugar and its effects on health.

The experts warned that many of these drinks are an unnecessary source of sugar and calories, and can increase the risk of obesity, type 2 diabetes and tooth decay.

They urged parents to only give children water or whole fruits instead of juice.

"It is not just tooth decay but there is increasing scientific evidence that regular sugary drink consumption is associated with an increased risk of type 2 diabetes and heart disease, independent of body weight, suggesting we are all vulnerable. Fruit juice and smoothies should not be part of a healthy balanced diet," commented one of the experts, UK cardiologist, Dr Aseem Malhotra.

The survey found that while portion sizes varied a lot, over half (117) were found to have six to seven teaspoons of sugar per 200ml equivalent. For example, while the Tesco Goodness Slurper Apple & Banana Fruit Smoothie Snack for kids was sold in a 90g portion size, its 200ml equivalent would contain eight teaspoons of sugar.

According to the experts, fruit juices do not need to be so sweet and products with less sugars are available if you read the labels carefully. However, they pointed out that while there is no need to add sugar to products made with fruit, 59 of the products tested also contained sugar or glucose-fructose syrup as an added ingredient.

They pointed out that whole fruits are naturally sweet and are good for you as they contain vitamins and fibre. When processed into juice drinks, the sugars in the cell walls of the fruit are released as ‘free sugars'. It is these sugars that damage teeth and provide unnecessary calories, as you take in more calories without feeling full, e.g. a 200ml glass of orange juice can contain three oranges.

"It is highly concerning that many parents are still buying fruit juices and juice drinks for their children thinking they are choosing healthy products. Children should be given as little juice as possible.

"What is more concerning are the products with added sugar and glucose-fructose syrup. We call on all manufacturers to stop adding more sugars to already sweet juices, particularly in children's products," added Kawther Hashem, a UK nutritionist with Action on Sugar.

The survey focused on juice products that were specifically aimed at children and included portion sizes ranging from 85ml to 500ml.