The myth seems to have grown from a few small, poorly-designed studies carried out over 45 years ago that suggested sugars may be linked to hyperactivity (10, 11), although they were unable to prove that sugar was the cause. These early studies set the ball in motion for more robust and extensive investigations, which went on to establish that sugars have no adverse effects on behaviour and do not lead to hyperactivity. This research includes a meta-analysis, which combined the results of 16 well-designed studies (5). The latter concluded that sugars do not affect children’s behaviour or cognitive performance, and suggested parents’ strong belief in a link may be due to expectancy and common association.
Research confirms that adults often ‘expect’ children to become ‘hyperactive’ after consuming sweets or other foods and drinks high in sugars. In one small study, mothers who described their children to be ‘sensitive to sugars’ were told they had consumed sugars even when they had not. Those mothers went on to report higher levels of hyperactive behaviour in their children, compared to a similar control group, despite them having no actual sugars (12).
The expectation and belief that sugars cause hyperactivity serve to reinforce the myth. If parents or teachers anticipate a behavioural change after consuming foods or drinks high in sugars, they may be more likely to interpret excited, lively, or energetic behaviour as hyperactivity. Furthermore, when adults believe two things are linked – such as high intakes of sugars and negative behaviours – they may be more likely to notice and remember times when both happen together, and to forget those times when they did not (13).
It also means other environmental influences or stimulating situations that affect behaviour and activity levels – such as parties, holidays, play dates, and screen use – may be overlooked, especially as they often coincide with a greater consumption of sugary foods and drinks. This further perpetuates the myth that sugars are responsible for hyperactive behaviour, when in fact, other factors are more likely responsible (13).
