In what they say is the first longitudinal finding of its kind, researchers report that boys who ate sweets daily at age 10 are significantly more likely to commit violent crimes in adulthood.
Researchers from Cardiff University in the United Kingdom, led by psychologist Simon Moore, studied 7000 people born in 1970 who were part of the British Cohort Study. They found that by age 34, 38 of the participants--90% of them male--had committed at least one violent offense. Of the 28 whose data could be analyzed, 69% ate "confectionery," (which covers candy and anything sugary), nearly every day during childhood. Only 42% of the nonviolent people had indulged daily, according to self-reports when the subjects were 10 years old.
Although lower education levels correlated with daily sweet-eating, the connection with violence remained significant even when the researchers controlled for factors such as family circumstances, parental attitudes, and IQ. "Try as I did, I couldn't get rid of the sweets-violence connection," says Morris.
Genes are an unlikely explanation because what 10-year-olds eat is largely governed by their immediate environment, the researchers report in the October issue of The British Journal of Psychiatry. They suggest that sweet-eating children don't learn to defer gratification and carry impulsive behaviors into adulthood. They also speculate that big candy eaters are also more likely to eat additive-laden food--which some researchers claim has adverse behavioral effects throughout life.
Dietary researcher David Benton of Swansea University in the United Kingdom is skeptical about the group's conclusions, saying the study fails to show a cause-and-effect relationship. He points out that sweet-eating could reflect other behavioral predispositions, or could reflect a particular social and cultural environment, or could signify that other, more healthful, things are absent from a child's diet.
Psychologist Adrian Raine of the University of Southern California in Los Angeles is more enthusiastic. "The findings are fascinating," he says. He says one possible explanation for the connection is that a predilection for junk food causes hypoglycemia. That involves drastic fluctuations in blood glucose levels: High glucose levels trigger major insulin secretion to soak it up, which then leads to a shortage of glucose. That, in turn, can lead to nervousness and irritability and provoke "a full-blown aggressive outburst," says Raine, who cites studies linking low blood glucose to violence and aggression.
This article has been amended. Data from 7000 of the 17,415 people in the British Cohort Study was used to generate these findings.