May 24, 2004 -- Artificial food colorings, preservatives, and other additives may play a role in increasing hyperactive behavior among young children, a new study suggests.
British researchers found removing food additives from the diet of a group of 3-year-olds caused a reduction in the children's hyperactive behavior reported by their parents. And when the food colorings and preservatives were added back into the children's diets, the parents reported an increase in hyperactivity.
Based on these parental reports of behavioral changes, researchers estimate that if the current 15% of children thought to have hyperactivity-related behavior problems were to go on an additive-free diet, the prevalence could be reduced to 6%.
However, although the parents reported significant changes in hyperactive behavior, the study showed no significant differences on clinical tests of hyperactivity related to the food additives.
"In the absence of the objective tests showing any effect, we have to be slightly dubious about that magnitude of that effect," says researcher John Warner, professor of child health at the University of Southampton.
But if these findings can be confirmed by further studies, researchers say removal of food additives from children's diets could help reduce their long-term risk of behavioral problems.
The Food Additive-Hyperactivity Link
Researchers say it's not the first study to come up with mixed results when looking at the relationship between artificial food additives and hyperactivity.
The notion that food could have an effect on children's behavior became popularized in the 1970s by allergist Benjamin Feingold, MD, who published the Feingold diet. He advocated a diet free of more than 300 food additives to treat hyperactivity.
Since then, many studies have looked at the issue, but most have failed to substantiate Feingold's claims or have shown only a small benefit in learning and behavioral problems in children with attention deficit hyperactivity disorder (ADHD).
"When everyone thinks of hyperactivity and diet, they automatically think now of food additives and colors and the Feingold approach," says Roseanne Schnoll, PhD, RD, associate professor of nutrition at Brooklyn College of the City University of New York. "Even though there is merit to it, none of the studies have backed it up tremendously."
But what Warner says is unique about this study is that they found an effect of food additives on non-hyperactive children as well as those with existing behavior problems.
"All children had small shifts in their behavior in the same direction when exposed to the additives," Warner tells WebMD. "If the children are already normal, then that's not a major issue. But if they've already got rather difficult behavior, that might be the final straw that makes it totally unacceptable."
New Study Adds to Debate
In this study, published in the June issue of the Archives of Disease in Childhood, researchers looked at the behavioral effects of removing and then adding back artificial food colorings and preservatives from the diets of 277 children living on the Isle of Wight in the U.K.
During the study, the children ate a strict diet free of food additives for one week. In the following three weeks, the children drank a fruit juice drink supplemented with 20 mg of food colorings and 45 mg of sodium benzoate (a food preservative commonly used in fruit drinks and carbonated beverages) or a placebo fruit drink each day on alternate weeks in addition to the food additive-free diet.
Neither the parents nor the children knew which beverage contained the additives, and the beverages were indistinguishable in appearance and taste. The children's behavior was evaluated before the study began and assessed in clinical tests and by the parents throughout the study.
The study showed that the parents reported significantly more disruptive behavior during the periods when the children drank the beverage containing additives, and there was a reduction in hyperactive behavior once the child stopped drinking the beverage.
But the clinical tests showed no increases in hyperactivity during these periods.
Researchers say the parents' ratings may be more sensitive to changes in behavior because parents experience their child's behavior over a longer period of time and in more varied settings and under less optimal conditions than in a clinical evaluation. They say that in trials looking at the effects of medications to treat ADHD, parents typically report the largest benefits of the drugs.
The study also showed that children with severe hyperactivity were no more or less likely to respond to the food additives than those with milder behavioral problems.
"If this can be replicated, there may be a significant public health message that we need to change people's perception of food, that it doesn't need to be highly colored to be nutritious," says Warner.
Finding a Diet to Fight Hyperactivity
Aside from the preservative and food colorings examined by this study, Schnoll says many other foods are commonly implicated in triggering hyperactive behavior and allergic reactions in children. They include chocolate, cow's milk, eggs, oranges, sugar, and wheat.
That's why she says it's so difficult to do these types of studies well -- it's hard to take out only one or two things from the diet and come up with what causes the problems in behavior.
Instead, Schnoll recommends a "few foods" or "elimination" diet for children with hyperactivity problems to determine if food reactions are playing a role in their behavior. The diet includes only a few foods that do not commonly cause allergic reactions, such as chicken, lamb, bananas, pears, rice, and potatoes.
The child stays on this diet for two weeks, and then the parents can start adding foods one by one back into diet and monitor for allergic reactions or changes in behavior.
"In all studies I have seen, this is best approach where you can actually see kids react after eating various certain foods," says Schnoll.
"There is a very big allergic component to hyperactivity where children who are hyperactive also have other types of allergic problems, such as eczema and asthma," Schnoll tells WebMD. "When you take them off these offending foods -- whether they're colorings, food additives, milk, dairy, or wheat -- it improves their allergic conditions, and also their hyperactivity improves."
In addition, Schnoll says not getting the proper balance of vitamins, minerals, and other nutrients can make children more susceptible to hyperactive behavior and other problems.
"We are getting too much of the trans fats and the omega-6 fatty acids from the plant oils and not enough of omega-3 fats that we find in walnuts, flaxseed, and fish," says Schnoll. "Not getting enough of these omega-3s can actually precipitate allergies and possibly hyperactive behavior."