Often overlooked in the debates about limiting soda consumption is its effect on behavior, particularly children's problem behavior.

Concerns about soda tend to focus on public health issues: Too much soda will make you fat. It will make your children fat and will increase your risk for diabetes. Drinking soda is known to contribute to dental problems and the rising rates of obesity in children and adults.

When it replaces healthier drinks such as milk, drinking soda may lead to deficiencies of nutrients such as calcium. Children who fill up on soda and other liquids often fail to eat nutritional solids leading to further health deficiencies of protein, iron and vitamins.

The more soda teens consumed, the more likely they were to be aggressive and experience depression, suicidal thoughts, and withdrawal behavior.

One of the reasons why less has been said about soda's effect on children's behavior is that it is difficult to pin down. After all, young children are naturally highly active and are just learning self control. And there are a variety of family and social factors that can all contribute to problem behavior.

Previous studies have shown that the more soda teens consumed, the more likely they were to be aggressive and to experience depression, suicidal thoughts, and withdrawal behavior.

Sadly, it appears that soda does pretty much the same thing to young children, according to a new study by researchers at Columbia University, the University of Vermont and Harvard's School of Public Health.

Separating The Effects of Soda on Behavior from Social Factors

The team examined data from the Fragile Families and Child Wellbeing Study, which followed 2,929 mother-child pairs in 20 large U.S. cities from the time the children were born. That study, run by Columbia University and Princeton University, surveys mothers periodically over several years. Mothers answered questions about behavior problems in their children and were asked to report how much soda their kids drank on a typical day.

Children who drank four or more servings of soda a day were more than twice as likely to destroy others’ belongings, to get into fights, and physically attack people, compared with children who drank no soda.

To be sure they were seeing only the effects of soda consumption on behavior, researchers had to separate out, or control for, a variety of factors that can affect kids' behavior. For example, extensive TV viewing and high consumption of sweets are known and suspected behavioral risk factors.

They also had to factor in social risk factors for problem behaviors. Having a depressed mother, family violence, an incarcerated parent can all cause children to act out. Children in the soda consumption group had to be matched with those in the no-soda group on a variety of other social factors — race/ethnicity, parents' marital status, maternal education, and the child’s body mass index.

The researchers used standardized research questionnaires to investigate all these co-factors and used a standardized child behavior checklist to assess the children’s behavior.

A Clear Culprit, But What Is the Cause?

The results were striking and hard to ignore.

Overall 43% of the children in the study group drank at least one serving of soda per day, and 4% drank more than four servings. The more soda a child drank, the more aggressive behaviors they showed. When the effects of drinking fruit juices, watching TV, and eating candy and sweets were taken into account, the effect of soda drinking remained a significant stand-alone risk factor for aggression, withdrawal and attention problems.

This was also true for social risk factors. Children who drank four or more servings of soda a day were more than twice as likely to destroy others’ belongings, to get into fights, and physically attack people, compared with children who drank no soda.

When the effects of drinking fruit juices, watching TV, and eating candy and sweets were taken into account, the effect of soda drinking remained a significant stand-alone risk factor for aggression, withdrawal and attention problems.

It is clear that drinking soda regularly has negative effects on children's behavior; it is not clear why this happens.

Some ingredient in soda — such as high fructose corn syrup, aspartame, sodium benzoate, phosphoric or citric acid or caffeine — may be causing the problem behaviors. But which one? It is not possible to tell based on this study, but the researchers note that caffeine has been linked to impulsivity and risk-taking in children and adolescents and they speculate that this might be the case for the caffeine content of soda.

Alternatively, the researchers propose that an underlying physiologic condition, such as low blood sugar, could both lead the children to want to drink soda and could be causing the aggressive behaviors. Or, it could be a combination of influences.

More research is necessary to pinpoint cause and effect.

What the study does do is add more evidence in support of the possibility that soda consumption and problem behavior, especially aggressiveness, go hand in hand.

For an increasing variety of health and behavioral reasons, it's a good idea to limit your child's consumption of soda. Parents may want to consider diluting their children’s sugar-sweetened beverages or simply replacing them with water or more nutritious liquids.

The study is published in the Journal of Pediatrics.