Food and Behaviour Research

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What is the short-term impact of sugary drinks in the classroom?



The results from this study clearly indicate a causal impact of sugary drinks on children's behavior and test scores


Controversy over whether sugar may have negative effects on children's behaviour and learning in the short-term has a long history, with fairly mixed findings from research to date.   (By contrast, the evidence really is now overwhelming that high-sugar diets are damaging to mental as well as physical health, wellbeing and performance in the longer-term.)

This new study reports that in boys of pre-school age, drinks sweetened with sugar vs artificial sweeteners led to negative effects on their classroom behaviour (increased restlessness), and learning (achievement in a maths assessment). 

Interestingly, in girls, no effects on behaviour were apparent; and unlike the boys, their maths achievement appeared to be slightly boosted by the sugary vs artificially sweetened drink. 

This was a randomised controlled trial (RCT) - acknowledged to be the best study design for investigating causality.  The results may not be overwhelming (particularly given the sex differences that appear to be somewhat downplayed in the headlines) - but any short-term effects of sugar consumption would be expected to differ between individuals in any case.

More fundamentally, for their brain health as well as physical health. there are many other good reasons to discourage children from anything but occasional sugary drink consumption. 

For the underlying research please see:

For further information please see:

See also:

03/11/2021 - Medical Xpress

A new study in Health Economics finds that sugary drinks impact behavior and math scores of preschool children.
In the study, investigators randomly assigned 462 children to receive sugary drinks or artificially sweetened drinks, and they collected data before and after consumption.
Consuming one sugary drink tended to induce an initial 'relaxing' effect for boys, before making them more restless. Girls' behavior was not significantly affected.
Also, consuming one sugary drink seemed to have a negative effect on student achievement in math for boys and a positive effect for girls.
"Our study is the first to provide large-scale experimental evidence on the impact of sugary drinks on preschool children. The results clearly indicate a causal impact of sugary drinks on children's behavior and test scores," said corresponding author Fritz Schiltz, Ph.D., of KU Leuven, in Belgium.
"The associated effects on in-class performance have major policy implications, as sugary drinks are still ubiquitously sold in schools and as the consumption of sugary drinks is typically higher among children from low-income households and among boys," added co-author Kristof De Witte, a professor at KU Leuven.