Can food affect behaviour?

I’d taken my then-five-year-old grandson out to a friend’s farm for the afternoon, and now we were driving back home, tired and hungry. When I stopped for gas, Sebastian asked if I’d get him a snack at the convenience store. Like any good grandma, I said yes. Within minutes of slurping down the Creamsicle that he’d chosen, Sebastian was bouncing up and down in his booster seat and singing loudly and out of tune. When I commented on the abrupt change in his behaviour, he told me, “Yeah, I think that’s why I’m not allowed to have Creamsicles.”

Was it just a fluke that after consuming a sugary, artificially coloured treat, Sebastian quite suddenly became rowdy and unable to sit still? Or do foods really affect young children’s behaviour? Parents argue strongly on both sides. Let’s look at what the evidence says.

TV chef Jamie Oliver conducted a campaign a few years back to change the school lunches in some British schools — replacing highly processed foods with fresh vegetables, fruits and whole grains. Teachers in the schools commented that they saw dramatic improvements in the children’s behaviours when they were eating the more nutritious lunches. But, of course, that’s not a scientific study.

A 1995 review of research on sugar and children’s behaviour reported in the Journal of the American Medical Association found that there seemed to be no overall impct on children, but added “effects on subsets of children cannot be ruled out.” In other words, while sugar may not affect all children, it may affect some.

If sugar's not the problem

If sugar’s not the problem, some food additives may be. A 2004 study in the Canadian Medical Association Journal found that when children were given foods with additives at some times, and foods without additives at other times, the parents rated the children as more hyperactive when given additives — even though they didn’t know which group of foods they had eaten. (A psychologist observing the children saw no difference, however.)

The parents’ perception was reinforced by a 2007 study in The Lancet that found that three-year-old children who were given drinks with common food-colouring additives showed higher levels of inattention, impulsivity and overactivity. Kids given larger amounts of the additives had greater changes in their behaviours. The researchers did note that while most of those in the study demonstrated clear differences in behaviour between the times they were given placebos and the times they had the additives, some children seemed unaffected by the additives.

Amanda Philip says her five-year-old daughter, Timber, would definitely be in the affected group. “She’s had Lucky Charms breakfast cereal, which has tons of sugar and food colouring in the marshmallows. If she eats too much of it, it makes her incapable of dealing with things she normally can handle, like her little brother ‘getting in the way.’ She screams at him and ends up crying,” says Philip.

When Timber had lunch at a friend’s house, Philip saw another reaction. Timber ate a corn dog (the kind that comes pre-made and frozen from the grocery store) for the first time. After eating it, Philip says, “she went absolutely bonkers. She was speaking loudly and very fast, she started doing weird things like using syringes to spray herself with milk, jumping on the furniture, running around and finally screaming hysterically.” Philip won’t be adding that item to her grocery list any time soon.

Lack of food can affect behaviour

Fleur Bickford points out that lack of food can also affect a preschooler’s behaviour. She tends to have hypoglycemia or low blood sugar herself, and when her son Liam was three, she noticed that his sudden outbursts and meltdowns always happened when a meal or snack had been missed or delayed.

“He doesn’t always seem to know that he’s hungry,” Bickford adds. “We just know because he has these dramatic meltdowns.”

As long as she keeps him fed at regular intervals — three meals plus three small nutritious snacks through the day — he stays calmer. The importance of this plan was reinforced when Liam, now five, started school. “We realized that some days he came home with his snack uneaten because he’d gotten too busy with other things to remember it, and this correlated with the teacher’s comments that he was acting up at times,” she says. “We told the teacher that if she was having problems with his behaviour, it could be that forgotten container of yogurt. Once she started reminding him to eat his snack, the problems stopped.”

So perhaps the best question to ask is not “Does food affect children’s behaviour,” but “Does food affect my child’s behaviour?” For some, the answer may be no, but for others it’s a definite yes. The next challenge then is narrowing down the culprit — not always easy since some foods contain multiple additives. Fortunately, the foods the nutrition experts keep telling us to eat (fresh vegetables and fruits and whole grains) are largely additive-free.

The usual suspects

A 2007 study in The Lancet, showing increased impulsiveness, overactivity and inattention in children given drinks with common food additives, looked at the following additives. Since the children were given a mix of all the additives, the study couldn’t determine if certain ones are connected to behaviour changes.

• sodium benzoate (a preservative)
• tartrazine (a yellow food dye)
• quinoline yellow (a yellow dye)
• sunset yellow (a yellow dye)
• carmoisine (not permitted in Canada)
• allura red (a red food dye)