Sugar causes hyperactivity in kids: A myth persisting for decades

The myth persists that sugar causes hyperactivity in children despite a lack of scientific evidence, says a pediatrician who put that belief to the test.

The work of Dr. Mark Wolraich, a professor of pediatrics at the Oklahoma University Health Sciences Center in Oklahoma City, has debunked the myth.

However, a non-scientific experiment by CBC News has essentially shown it's still alive. 

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The experiment, over Halloween, aimed to see if parents believed candy led their children to bounce off the walls.

"They tend to not listen or get ready for bed if they've had too many desserts," said Pak Hum.

"She just can't focus," said Julie Snyder. "Can be any time, but definitely when she's on sugar."

For his part, Wolraich tried to establish a definite link between sugar and behaviour through observational and double-blind studies.

"When we finished the dietary study, it was published in the New England Journal of Medicine and there was a fair amount on the national news," Wolraich recalled. "Within two or three years, they seemed to forget."

Reasons not to indulge in sweets

Wolraich's meta-analysis reviewing 15 articles on sugar and artificial sweetener said the findings were clearer than any other analysis he had done on the subject. 

Wolraich believes that when children are overactive, it often relates to changes in their routine, such as Halloween or birthday parties.

"If you have the belief their behaviour is worse and those are usually times when they get large amount of sugar, it's not surprising you would see the difference."

He points to another experiment where parents who thought their children were adversely affected by sugar tended to stand closer to them, and to be more demanding of them. "The parents' suggestion can be fairly strong in that case."

The other health reasons to avoid eating too much sugar still stand. For example, nutrition experts and dentists say candy is fine in moderation, but it is rich in calories and can be hard on oral health.