London: Many parents are unwittingly egging on their kids to drink smoothies and juices, blissfully unaware that a combination of high acid levels and sugar can erode their teeth.
Instead of seemingly healthy fruit juice, children should preferably be given water and a handful of chocolate buttons for the sake of their teeth, said Kathy Harley, dean of the dental faculty at the Royal College of Surgeons.
Manufacturers are required to publish nutritional content of drinks on the label - but not their levels of acid, which can invite tooth decay, according to an investigation conducted by The Sunday Telegraph.
Harley said 50 percent of five-year-olds now show signs of damaged tooth enamel caused by excess acid in their diet. While health-conscious parents meant well in trying to feed their kids fruit and vegetables, the acid and sugar combo in juice meant they should be restricted to a "once a week treat".
Tooth enamel begins to be destroyed when acid levels in the mouth drop below 5.5 on the pH scale, which has 7 as neutral and one as strong acid.
While water has a pH of 7, and milk is just below at 6.8, our investigation found that a soft drink called This Water with lemons and limes, which describes itself as a "juice drink blended with pure squeezed juices and pure spring water," had a level of 2.7 - making it more acidic than cider vinegar, which had a level of 2.9.
This Water also contains 9.5 teaspoons of sugar in a 420 ml bottle. In 2008, the company had an ad campaign banned by the Advertising Standards Authority for failing to inform consumers about the sugar content of its juice drinks.
The other fruit drinks tested, including Tropicana orange juice, Copella apple juice, Innocent smoothies, Capri Sun orange drink and Robinsons Fruit Shoot apple and blackcurrant low sugar drink all had acid levels ranging between 3.3 and 3.8.
The most acidic beverage tested was Coca Cola, with a pH level of 2.5 and 12.5 teaspoons of sugar in a 500 ml bottle.
Harley said: "The only healthy drinks for teeth are milk and water. Children are having fruit drinks and smoothies several times a day, when they these should be considered as a treat, something to have once a week."