Wednesday, August 11, 2010

Does Too Much Sugar Turn Children Into Violent Criminals?

Parents: A strict warning--you'd better withhold that bowl of fruity pebbles from your child, because if you don't, they might grow up to be a violent criminal. Or at least, that's the nonsense that some out there would have you believe.

A recent (2009) study from Cardiff University in the U.K. found that children who ate more sugary foods were more likely to commit violent crimes as adults. Sixty-nine percent of violent offenders were daily sugar eaters, they say, compared with 42% of non-violent people. Therefore, sugar must be turning our kids into future delinquents.

But before you rush to rid your home of the devilish powder, we thought we'd shed a little light on the subject, because it annoys us when people misuse science to create fantastic headlines in order to gain media attention that will mislead the public while scaring them about a whole lot of nonsense. Phew...that was a long sentence.

We start with the first rule of research: correlation does not equal causation. Just because two things can be linked together does not mean one causes the other. This is all the more true when something has no established mechanism for the outcome. That is to say, there is no credible evidence indicating how slightly elevated levels of sucrose in a child's body would alter brainwaves in order to change their behavior and lead to violence.

Claiming sugar causes violent crime is a bold statement. So does sugar really have such powerful effects? Unlikely. Let's talk about the more rational causes for such a correlation:

A) Those with higher daily sugar habits are also those who are likely to exhibit less self-control. Less self-control is an established link to violent crime and delinquency, and it is the lower inhibitions that lead both to increases in crime and increases in sugar intake.

For example, the famous marshmallow experiment at Stanford University provides the perfect analogy. Researchers put children into a room with nothing but their own devices to entertain them. A marshmallow was placed on the table in front of them, and the preschoolers were told that if they waited until the researcher .came back into the room to eat it, they would be given a second marshmallow. About a third of the kids managed to hold out the full 15 minutes, a third ate the marshmallow right away, and around a third broke down somewhere in-between.

Years later, a follow up study was done when the kids were young adults. (2) It found that those in the most impulsive group scored significantly higher on delinquency rates and significantly lower on general life measures. Those kids who as preschoolers had waited the 15 minutes to earn a second marshmallow had significantly higher marks in education and everyday life skills. So does this mean eating marshmallows causes future delinquency? No. It means that a lack of self-control in childhood, as evidenced by the marshmallow test (or impulsive sugar intake) is a predictor of future delinquency.

B) Those parents who largely fail to monitor a child's diet when young are likely to also be parents who are less-competent and caring in general. Less competent parenting is a proven link to crime, and low parental caring is a proven link to antisocial behavior. So those who were able to eat candy for breakfast would tend to be those with more irresponsible and less involved parents.

C) Low socioeconomic status (SES) is a proven link to crime; and there is also an established link between low SES and poor, higher-fat, higher sugar diets; simply because junk food tends to be cheaper and more readily available than healthy food.

The idea that sugar alters behavior in kids is a widely held myth. At least a dozen large-scale trials analyzing what children eat have been unable to detect any differences in behavior between the children who ate sugary foods and those who hadn't. Even studies that singled out children who were labeled as having "sensitivity" towards sugar found no behavioral differences between a high-sugar and sugar-free diet. If a child was an obnoxious twerp before downing a bag of skittles, they'll be one afterward too. And if they were calm and in-control before ice cream, they won't suddenly grow devil-horns afterward.

No doubt there are parents out there convinced that sugar makes their kids hyper, and they are no doubt gritting their teeth reading this.
Such parents have been the subject of study too. In one example, researchers divided children and their parents into two groups. In one group, parents were told their children were being given a drink that was full of sugar. The other was told their children's drinks were sugar free. In truth, both groups received sugar-free drinks. The parents were then asked to grade their children's behavior. Naturally, parents who thought their children had received a sugar-boost graded them as more hyperactive than the other. (6) Our beliefs shape our perspectives, and create an altered version of reality. We find evidence for what we expect to find, while ignoring evidence to the contrary.

Of course, too much sugar does do many unhealthy things: it rots your child's teeth, leads to obesity, and is generally the sign of a poor diet, because too much of sugary foods generally means not enough of the other, healthier variety. But turn children into budding psychopaths it does not. Moderation and self-control are the keys. In fact, I'd wager that the kid whose overprotective parent never allows them any sugary treats is more likely to go insane and become an ax-murderer than those reasonable parents who allow sugary treats in healthy moderation.

1. Discover Magazine, 'The Bad News,' December 2009, p. 16

2. Y. Shoda, W. Mischel & P.K. Peake, "Predicting adolescent cognitive and social competence from preschool delay of gratification: Identifying diagnostic conditions." Developmental Psychology, 26, pp. 978-986, 1990

3. M. Kinsbourne, "Sugar and the hyperactive child," New England Journal of Medicine, 330(5): 355-56, 1994

4. D.A. Krummel, F.H. Seligson"& H.~. Guthrie, "Hyperactivity: is candy causal?" Critical Reviews in Food Science and Nutrition, 36, (1-2): 31-47, 1996

5. M.L. Woolraich et al., "Effects of diets high in sucrose or aspartame on the behavior and cognitive performance of children." New England Journal of Medicine, 330(5): 301-07

6. D.W. Hoover & R. Milich, "Effects of sugar ingestion expectancies on mother-child interactions." Journal of Abnormal Child Psychology, 22(4): 501-15, 1994

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