In a test of Feingold's hypothesis that food additives trigger the hyperactive response, 26 hyperactive children were randomly assigned to treatment conditions whereby they were given active or placebo medications in combination with challenge cookies with artificial food colors or control cookies without the additives. The children were crossed over into each of the four treatment conditions and experimental procedures were employed, including double-blind assessments through the completion of behavior checklists, by teachers and parents.
Stimulant medications were clearly more effective than diet in reducing hyperactive behavior. The parent ratings indicate strong drug effects and inconclusive diet effects. Drug effects are marked in teacher ratings as well. However, when the children were receiving placebos, their hyperactive behaviors in the classroom were greater when eating cookies with artificial colors than when eating cookies without artificial colors.
According to the ratings, approximately seven children were no longer hyperactive. There is evidence to suggest that the behavior of three to eight children was diet-responsive, depending on the criteria used. There is evidence, particularly in teacher ratings, in support of Feingold's hypothesis if it is modified.
Further research is required to specify which subtypes of hyperactive children respond to a diet free of artificial food colors.
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