The story unlocks once you make your call.
A myth. No effect found. The parents' expectations did all the work.
Where it came from
The idea took hold in the 1970s, alongside diets that blamed additives for behaviour problems. Birthday parties, where children eat sweets and run wild, seemed to prove it every weekend.
What’s actually true
Double-blind trials, in which neither the children nor the adults know who got sugar and who got a sweetener, find no difference in behaviour. A 1995 review in JAMA pooled sixteen such studies and found no effect.
What does change is the watching. In one experiment, mothers told their sons had just had sugar rated them as more hyperactive, even though every boy had been given a placebo.
Further reading
- Wolraich, Wilson & White, “The effect of sugar on behavior or cognition in children”, JAMA (1995)
- Hoover & Milich, Journal of Abnormal Child Psychology (1994)