The WHO has commissioned a second study, to be published sometime in the next few months, looking at sugars and tooth decay and will consider both analyses in its updated recommendation, Nishida said.
"Reducing the amount of sugar consumed in drinks deserves special attention because of the strength of the evidence and the ease with which excessive sugar is consumed in this form," said Walter Willett, a professor at the Harvard School of Public Health, and David Ludwig, a professor at the Boston Children's Hospital, in an editorial accompanying the study. "But questions remain. What is a desirable limit?"
In September, New York City's Board of Health approved Mayor Michael Bloomberg's plan to restrict sales of sugary soft drinks to no more than 16 ounces (450 grams) a cup. They rejected arguments from Coca-Cola Co., PepsiCo Inc. and restaurant companies whose coalition says the issue is about consumers' freedom to choose. The mayor is founder and majority owner of Bloomberg News parent Bloomberg LP.
Recent efforts to tax soft drinks have foundered in at least 30 U.S. states. The federal government rejected an attempt in 2011 to bar purchases of sugared drinks with food stamps.
In Europe, a sugar tax in Denmark was abandoned in November after a fat tax was criticized for raising prices and droving consumers to shop in neighboring countries like Germany.
Soft-drink makers say their products contribute 7 percent of calories to the average daily diet in the U.S. and 3 percent in Europe, too little to be the cause of obesity.
Weight gain can be slowed by paying attention to the amount of calories consumed and burned through exercise, the American Beverage Association has said. Soda makers have offered smaller packages, labeled products with clearer calorie counts and agreed to stop selling sugary drinks in most schools.