The study's lead author cautioned, however, that the increase may not be noticeable for individual children and that researchers can't prove soda caused the bad behaviors (see: "the Twinkie defense").
That said: "We found a significant relation with soda consumption with the overall measure of aggression and with the three specific behaviors we felt were most indicative of aggression: destroying things belonging to others, getting into fights and physically attacking people," the authors, led by researcher Dr. Shakira Suglia, an assistant professor of epidemiology at Columbia University's Mailman School of Public Health in New York City, said in a statement. The study was published August 16 in the Journal of Pediatrics.
For the analysis, the researchers used an existing study of mothers and their 2,929 5-year-olds from 20 large U.S. cities. The participants were first recruited between 1998 and 2000 to be periodically interviewed and evaluated.
Moms filled out a questionnaire on their children's behaviors over the previous two months to assess withdrawal, attention and aggression. Questions involved such things as how often the kids destroyed their own belongings and the belongings of others and attacked people.
The mothers were also asked how many servings of soda their children drank per day, and about other habits, such as TV watching.
Overall, 43 percent of the kids drank at least one soda per day. Four percent drank four or more.
Aggressive behavior was measured on a scale between 0 and 100, with higher scores indicating more aggression. Sixty-five was used as the clinical marker for when the child was considered to have a "problem."
Kids who reportedly drank no soda scored an average of 56 on the aggression scale. Those who drank one soda a day scored an average of 57. Those who drank two scored 58; three-soda drinkers averaged 59. Kids who drank four or more sodas a day averaged 62 -- getting pretty close to the red zone.
After taking into account other bad habits that may have influenced the results -- such as how much TV the kids watched, and how much candy they ate -- as well as other things that could be upsetting (if mom was depressed, or dad was in jail), the researchers still found that drinking four or more servings of soda per day was tied to higher aggression scores.
Kids who drank four or more sodas a day were twice as likely to destroy other people's belongings, get into fights and physically attack people, compared to children who didn't drink soda.
Soda drinkers also scored higher on scales measuring signs of withdrawal and attention problems, according to the researchers.
The researchers say they don't know what it is about soda that could account for the increased aggression, but they'd like to go out on a limb and suggest that it could be an ingredient in soda, such as caffeine or high-fructose corn syrup.
"Soft drinks are highly processed products containing carbonated water, high-fructose corn syrup, aspartame, sodium benzoate, phosphoric or citric acid, and often caffeine, any of which might affect behavior," they wrote. They said that limiting or eliminating soft drinks from kids' diets could reduce their behavioral problems.
However, another possibility is that an underlying condition, such as low blood sugar, could make kids more aggressive and make them crave soda, they say. Not very likely.
Suglia also said the results may not apply to the general population, because most of the mothers were single and African American or Latina. (White kids don't spaz out?)
"It is a leap to suggest that drinking soda causes these or any other behavioral issue," the American Beverage Assn. responded in a statement. "The science does not support that conclusion."
Really? We'd like to challenge Mr. American Beverage Assn. to spend an hour in a locked room with a kindergartner who's just pounded a six-pack of Coke.
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