Fiscal policies that lead to at least a 20 per cent increase in the retail price of sugar-sweetened beverages such as fizzy drinks, fruit drinks from concentrates and lemonade would result in "proportional reductions" in consumption, the new paper said.
A levy of this kind would also help reduce obesity, type 2 diabetes and tooth decay by cutting out more "free sugars" from consumers' diet.
Free sugars are added to foods and drinks by manufacturers, cooks or consumers, and include glucose, table sugar, honey, syrups and fruit concentrates. Their consumption is a "major factor" in the global obesity and diabetes epidemics, according to Dr Douglas Bettcher, director of WHO's department for the prevention of non-communicable diseases.
Dr Francesco Branca, director of WHO's department for nutrition for health and development, said: "Nutritionally, people don't need any sugar in their diet. WHO recommends that if people do consume free sugars, they keep their intake below 10 per cent of their total energy needs, and reduce it to less than five per cent for additional health benefits.
"This is equivalent to less than a single serving (at least 250ml) of commonly consumed sugary drinks per day."
Osborne's levy will make soft drinks companies pay a charge for drinks with added sugar, and total sugar content of five grams or more per 100 millilitres.
The UK's sugar tax has been slammed by industry bodies, companies and campaign groups, who claim the tax will disproportionately hit poor families and will have a minimal effect on consumption, though health campaigners have backed the levy.
Chris Snowdon, director of lifestyle economics at the Institute of Economic Affairs, said:
While infectious diseases continue to ravage large parts of the world, it’s pathetic to see the WHO fretting over the price of lemonade.
Sugar taxes have never reduced obesity in any country that has experimented with them. They barely affect the number of drinks consumed, let alone people’s waistlines. Sugar taxes are effective ways of getting money out of poor people, but that hardly seems a legitimate objective for a UN agency. The WHO is becoming a laughing stock and urgently needs reform.