Does Sugar Make You Violent?

If you read the nutrition science headlines, you might have seen these: “Giving in to pester power can make your child a thug” or “Daily sweets ‘linked to violence’“. They refer to a new paper that just came out which claims that eating sugary snacks every day as a child has an impact on your behavior as an adult. The idea seems impossible. I mean, sure, we all have thought about slugging that really slow guy in the line in front of us at the ice cream parlor when we’re craving a nice, double scoop of Death by Chocolate. But giving my child a piece of chocolate after dinner every night can’t make him into a violent person… Or can it?

The researchers explain that it’s possible that giving children sweets and chocolate regularly may alter their adult behaviors directly, because of simply eating sugar, or indirectly, because it prevents kids from learning self control. The idea is that if they’re given what they want when they want, they lean towards impulsive behavior, which previous research has strongly associated with delinquency.

But no one had ever looked at whether there are long term effects of childhood diet on adult behavior. So, researchers from Cardiff University decided to analyze at the relationship between adulthood violence and childhood diet using survey data of almost 17,500 people to see if eating sweets as a kid makes people more violent. They say it does, but critics of the research are not so sure. Julian Hunt, the director of communications for the British Food and Drink Federation, was quoted as saying:

“This is either utter nonsense or a very bad April Fool’s Day joke… Anti-social behavior…is not linked to whether or not you ate sweeties as a kid.”

Can a childhood sweet-tooth make you violent as an adult? Read how the study was conducted and its conclusions, and you be the judge:

The Study

Dr Simon Moore and his colleagues were able to use a previously-collected data set of 17,415 people which were surveyed at ages 5, 10 and 34. The participating people and their parents were questioned about health, education, and other life factors like whether they owned a car. When the study participants were 10, they were asked how often they ate sweets, and their answers were grouped into “every day” or “less often/never”. Later, at age 34, the participants self-reported convictions for violent offenses. The research team then statistically compared the likelihood that sweet-eating at a younger age affected a participant’s likelihood of being violent later on.

The Results

According to the study, you really should keep your kids away from sweets: those that ate them every day at age 10 were significantly more likely to have been convicted for violence at age 34, even when other factors like parenting behavior, the area where the child lived, not having educational qualifications after the age of 16 and whether they had access to a car. Sweets were eaten daily as a ten year old by 69% of the violent offenders but only 42% of the non-violent participants. Researchers indicate that this is a strong connection which can’t be ignored.

But…What?

While the study shows that sweets might have an impact on behavior, it does have many drawbacks.

Firstly, the scientists had a very crude measure of sweets intake. It’s clear from the breakdown of “every day” and “not” that they aren’t nutritionists, they’re psychiatrists. A better study would have looked at the volume, weight and kind of sweets eaten over a number of childhood years to fully appreciate the children’s dietary habits. After all, one chocolate bar is very different from a bag of sour patch kids nutritionally. And they didn’t even include soda and sugary drinks… c’mon!

Secondly, the number of violent offenders in the group was so small, statistically speaking, that it was harder to determine differences between population groups. Moreover, there were large numbers of sweet-eaters in both non-violent and violent subsets, so the causal link between the two is a little shaky.

You would expect that if the sweets themselves or the constant pandering to a child’s demands had a marked impact on behavior, much less than 42% of the non-violent people would have had daily sweets.

Thirdly, as it was taken from a general survey study, the questions themselves were not designed to examine the relationship between diet and behavior in detail. It didn’t include questions about aspects of life that may have been important, including big ones like family income. While this doesn’t mean that the results of the data are invalid, it does mean that they may be incomplete, and those missing pieces might contain pertinent information.

Lastly, in general, there are a number of reasons why children who eat more sweets might have violent records later in life, most of which are not caused by sugar or giving in to kids demands. Leaving out certain measures of socioeconomic status is a huge mistake on the researchers part, because in general, many aspects of diet, especially including sugar intake, have been shown to be linked to social class and money situations – factors which also have an influence on crime. As well, the study didn’t overall account for whether violence-prone children happen to prefer sweets more than other kids, thus reversing the presumed causal relationship between eating sweets and being violent.

Personally, I think that while this study is interesting, it’s weaknesses make it far from conclusive. I’d like to see a much more carefully designed experiment look at the relationship between childhood diet and adult aggression. But, at the same rate, it might not hurt to say no to your kids every once in a while when they ask for treats. After all, learning self control and discipline has never been linked to becoming a violent offender.

Reference:

Moore, S., Carter, L., & van Goozen, S. (2009). Confectionery consumption in childhood and adult violence The British Journal of Psychiatry, 195 (4), 366-367 DOI: 10.1192/bjp.bp.108.061820