Clinical Question: Does a diet that restricts food coloring and preservatives improve hyperactive behavior in three-year-old children?

Setting: Outpatient (primary care)

Study Design: Crossover trial (randomized)

Synopsis: The authors evaluated the effects of a restricted diet on 397 three-year-old children who were classified as hyperactive/atopic, hyperactive/nonatopic, nonhyperactive/atopic, or nonhyperactive/nonatopic. The study was split into two one-week treatment periods, separated by one-week washout periods. The children were to remain on a diet free of artificial coloring and benzoate preservatives for the entire four weeks.

During the first week, the children were assigned randomly to receive a daily drink free of artificial coloring and sodium benzoate or an artificially colored and preserved drink identical in appearance. The children were switched to the opposite drink during the second treatment period. Adults were unable to distinguish the taste of these beverages, and the families and study personnel were blinded to the specific treatment assignments.

Only 70 percent of the enrolled patients finished the study, 61 patients never started the study, and 59 patients dropped out. Fifteen of the 59 parents who withdrew their children from the study did so because of behavior changes. Nine of the withdrawals occurred during an active week and six during a placebo week. At the end of the study, the parents were divided equally into those who did and those who did not correctly identify the order of the drinks. Based on the parents’ ratings, their children were calmer during the week when no artificial coloring and preservatives were given. The trained observers, however, detected no significant differences during any of the treatment periods.

Bottom Line: Placing three-year-old children on a diet that restricts food coloring and preservatives has no effect on hyperactive behavior, as observed by trained evaluators. However, the parents who live with these children for the remaining 23 hours of the day report improvements in hyperactivity. The results were the same whether the children were hyperactive or atopic. (Level of Evidence: 2b)