More must be done to curb the nation’s sugar intake to reduce the “costly burden” of tooth decay, experts have said.

People should get no more than 3% of their daily calories from sugars, experts said.

Current World Health Organisation (WHO) recommendations state that adults should get no more than 10% of their daily calories from “free” sugars. And the NHS says that “added sugar” such as sucrose, hydrolysed starch and honey should not make up more than 10% of the total calories people get from food and drink each day.

But researchers from University College London (UCL) and the London School of Hygiene and Tropical Medicine said 5% should be the absolute maximum with people aiming for a target of just 3%.

The comments come after they examined public health records from countries across the world in order to assess diets and dental health of large populations of both adults and children.

They found that sugar intake which accounted for 10% of energy intake, or calories, “induces a costly burden of caries (tooth decay)”.

“This largely preventable disease is still common,” the authors wrote in the journal BMC Public Health.

“Despite the use of fluoride and improvements in preventive dentistry, the burden of dental caries remains unacceptably high worldwide.”

Study author Aubrey Sheiham, emeritus professor of dental public health at UCL, said: “Tooth decay is a serious problem worldwide and reducing sugars intake makes a huge difference.

“Data from Japan were particularly revealing, as the population had no access to sugar during or shortly after the Second World War. We found that decay was hugely reduced during this time, but then increased as they began to import sugar again. Similarly, only 2% of people at all ages living in Nigeria had tooth decay when their diet contained almost no sugar, around 2g per day. This is in stark contrast to the USA, where 92% of adults have experienced tooth decay.”

The authors recommended a series of steps health officials could take to reduce sugar intakes including sugar taxes and reforms to food packet labelling.

Professor Philip James, honorary professor of nutrition at the London School of Hygiene and Tropical Medicine, added: “We need to make sure that use of fruit juices and the concept of sugar-containing treats for children are not only no longer promoted, but explicitly seen as unhelpful. Food provided at nurseries and schools should have a maximum of free sugars in the complete range of foods amounting to no more than 2.5% of energy.

“Vending machines offering confectionary and sugary drinks in areas controlled or supported financially by local or central government should be removed. We are not talking draconian policies to ’ban’ such sugar-rich products, which are available elsewhere, but no publicly-supported establishment should be contributing to the expensive problems of dental caries, obesity and diabetes.

“The food industry should be told that they should progressively reformulate their products to reduce or preferably remove all the sugars from their products. New food labels should label anything above 2.5% sugars as ’high’.

“A sugars tax should be developed to increase the cost of sugar-rich food and drinks. This would be simplest as a tax on sugar as a mass commodity, since taxing individual foods depending on their sugar content is an enormously complex administrative process. The retail price of sugary drinks and sugar rich foods needs to increase by at least 20% to have a reasonable effect on consumer demand so this means a major tax on sugars as a commodity. The level will depend on expert analyses but my guess is that a 100% tax might be required.”