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People will be advised to halve the amount of sugar in their diet, under new World Health Organization guidance.

The recommended sugar intake will stay at below 10% of total calorie intake a day, with 5% the target, says the WHO.

The suggested limits apply to all sugars added to food, as well as sugar naturally present in honey, syrups, fruit juices and fruit concentrates.

UK campaigners say it is a "tragedy" that the WHO has taken 10 years to think about changing its advice.

The recommendation that sugar should account for no more than 10% of the calories in the diet, was passed in 2002.

It works out at about 50g a day for an adult of normal weight, said the WHO.

It is a tragedy that it has taken 10 years for the WHO to think about changing their recommendation on sugar Katharine Jenner, Action for Sugar

However, a number of experts now think 10% is too high, amid rising obesity levels around the world.

Announcing the new draft measures, the WHO said in a statement: "WHO's current recommendation, from 2002, is that sugars should make up less than 10% of total energy intake per day.

"The new draft guideline also proposes that sugars should be less than 10% of total energy intake per day.

"It further suggests that a reduction to below 5% of total energy intake per day would have additional benefits."

Dr Francesco Branca, WHO's nutrition director, told a news conference that the 10% target was a "strong recommendation" while the 5% target was "conditional", based on current evidence.

"We should aim for 5% if we can," he added.

Facts about sugar Evidence shows most adults and children in the UK eat more sugar than is recommended as part of a healthy balanced diet

Food and drinks that have a lot of added sugar contain calories, but often have few other nutrients

Sugary foods and drinks can also cause tooth decay, especially eaten between meals

Sugar found naturally in whole fruit is less likely to cause tooth decay than juices or blends because the sugar is contained within the body of the fruit

Source: NHS Choices Q&A: How much sugar should we eat? Five foods surprisingly high in sugar

The plans will now go for public consultation, with firm recommendations expected this summer.

Public Health England said its scientific advisory committee on nutrition was reviewing evidence on sugar in the UK diet.

Director of Nutrition and Diet, Alison Tedstone, said: "Our surveys show that the UK population should reduce their sugar intake as average intake for adults is 11.6% and for children is 15.2%, which is above the current UK recommendation of 10%. "

Campaign group, Action for Sugar, said it was pressing for 5% to become the firm recommendation.

Nutritionist, Katharine Jenner, said: "It is a tragedy that it has taken 10 years for the WHO to think about changing their recommendation on sugar, which will have had astronomic implications on the millions affected by obesity and type 2 diabetes the world over. "

The WHO guidelines are based on a review of scientific evidence on the health impact of sugar, including damage to teeth and the effect on obesity.

The obesity study, published last year in the BMJ, found while sugar did not directly cause obesity, those who consumed a lot of it, particularly in sweetened drinks, tended to put on weight as sugary food did not make them feel full.

A review of the link between sugar intake and tooth decay, carried out by UK researchers, found cases of tooth decay were lower when sugar made up less than 10% of daily calories.

Paula Moynihan, Professor of Nutrition and Oral Health at Newcastle University, said: "The less sugar you eat, the lower your risk of dental decay."

Prof Tom Sanders of the School of Medicine, King's College London, said a limit of 5% added sugar "would be very tough to meet".

He added: "5% is untried and untested; 10% we can live with."

Dr Nita Forouhi, of the Medical Research Council Epidemiology Unit at the University of Cambridge, said the 5% target was "ambitious, and challenging".

On Tuesday a leading doctor called for a tax on sugar to help combat growing levels of obesity.

Dame Sally Davies, England's Chief Medical Officer, told MPs: "We may need to move toward some kind of sugar tax, but I hope we don't have to. "