Body & HealthFact
Sugar doesn't make kids hyperactive. Parents just expect it.
A 1995 meta-analysis reviewed 23 controlled studies in which children were given sugar or a sweetener without knowing which. Result: no measurable effect on behaviour or attention. In a further experiment, parents were told their child had eaten sugar when it was placebo, and promptly rated the child as more hyperactive. The effect is in the observer.
Useful: Birthday parties are exciting because of the party, not the cake.
Source: doi.org