Does sugar make kids hyper?

It's a weel know fact, sugar makes kids go round the bend. But is it really true?
27 September 2016

Interview with 

Dr Kat Arney, The Naked Scientists


In this week's Mythconception Kat's been sifting through the sweet stuff...

Kat - That's right! Picture the scene - a kids' birthday party, complete with a table laden with sugar-packed goodies. Just a few slices of cake or choccie biccies seems to turn the mildest child into a hyperactive monster, quickly creating a situation of knee-high near-anarchy. But while it's a commonly-held belief that dosing kids up on sugar makes them hyperactive and badly-behaved, like a badly-organised pile of party cookies, the scientific evidence behind these claims just doesn't stack up.

Brave scientists have actually carried out research into the links between children's diet and their behaviour, dating back more than 20 years. For example, in 1994 scientists published a major study in the New England Journal of Medicine describing a nine-week-long, placebo-controlled trial looking at the effects of sucrose (that's regular table sugar to you and me) and the artificial sweetener aspartame on the behaviour of nearly 50 pre-school and school-age kids - including children whose parents reported them as being particularly sensitive to the hyper effects of sugar. What's more, they specifically picked children whose parents said they were sensitive to sugar. Although it's difficult to carry out these kind of studies with 100 per cent accuracy - kids will be kids, after all, and it's hard to completely control what they eat and do - and although the studies usually only involve a relatively small number of participants, the researchers concluded that "neither sucrose nor aspartame produces discernible cognitive or behavioral effects in normal preschool children or in school-age children believed to be sensitive to sugar."

This finding was backed up by another paper published in 1995 - something called a meta-analysis, which combines many studies looking at a particular question to see if there are any effects once a larger number of participants is grouped together. Again, it concluded that "sugar does not affect the behavior or cognitive performance of children. However, a small effect of sugar or effects on subsets of children cannot be ruled out."

So given that the studies say that there's either no effect, or maybe only a tiny one, why do parents still swear that sugar turns their little angels into little monsters? It actually seems to come down to parental expectations. Put simply - if parents see their children eating lots of sugary food, they believe that they're going to act up, and so attribute any naughtiness to the sugar. This was even tested in a placebo-controlled trial with mothers and sons, where half the mums were told their children were necking a sugary drink, while the others were told they were getting a drink with artificial sweetener, even though they were all given the artificial sweetener rather than sugar. But the mothers who thought their sons had drunk lots of sugar were more likely to say their child was acting up. The mums themselves actually criticised the apparent sugar-drinking kids more, and watched them much more closely.

In fact sugary drinks seem to alter parents' behaviour rather than children's - if you believe sugar is going to make your child behave badly, that's what you're going to be looking out for. And it goes without saying that children's parties are ground zero for reinforcing this idea - lots of sugary foods on offer, plus over-excited kids doing lots of fun activities that get them hyped up, and an expectation from parents that it will be a living nightmare. But it's more likely to be that expectation - along with the overall excitement of the event - that is responsible for unruly behaviour, whether real or imagined.

There's still research going on to find out whether sugar - or, indeed, artificial sweeteners - have any link to childhood conditions such as ADHD, but for now there isn't enough hard evidence to be sure. But of course, nobody is saying that it's fine to let kids guzzle on sugary drinks, cakes and chocolate bars all day long. After all, healthy foods such as fruit and vegetables all contain certain amounts of sugars in various forms. But there are plenty of good reasons for kids - and adults - to keep an eye on the amount of sugar in their diet. For example, eating lots and lots of sugary foods increases the likelihood of obesity, which can cause problems later in life. But bad behaviour doesn't seem to be one of them.


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