diet of hyperactive children. On the basis of his clinical work, Feingold claimed that a diet free of food additives and natural salicylates led to dramatic improvements, with 50 to 70 percent of the hyperactive children placed on this diet displaying complete remission. To obtain success, Feingold insisted that adherence to the diet was mandatory: any infringement could lead to a return of symptoms. He also proposed that successful treatment required the entire family to be on the diet and that an individual sensitive to food additives must avoid them for life. Feingold's ideas were widely publicized and rapidly gained popularity among the public (Lipton et al., 1979; Conners, 1984).
Open clinical trials, in which parents or physicians placed children on an additive-free diet supported Feingold's claims. However, carefully controlled double-blind studies have generally yielded more negative results (e.g. Conners et al., 1976; Harley et al., 1978; Goyette et al., 1978; Weiss et al., 1980). Using a dietary replacement paradigm, Harley and colleagues (1978) compared the behavioral effects of Feingold's diet with an ordinary diet containing additives. Food for families in the study was provided by the experimenters, and neither the researchers nor the family knew which diet was being consumed at any particular time; diet phases were alternated so that all families ate both diets. No significant improvements in behavior were noted by teachers or objective raters in the 36 school-aged hyperactive boys in the study. However, some parents reported improvement on the Feingold diet, but this occurred only when the diet was given after the control diet. When 10 preschool children were tested in the same situation, all of their mothers and most of their fathers rated the children as more improved on the additive-free than on the control diet. Harley and colleagues (1978:827) concluded, ''While we feel confident that the cause-effect relationship asserted by Feingold is seriously overstated with respect to school-age children, we are not in a position to refute his claims regarding the possible causative effect played by artificial food colors on preschool children."
The effects of food additives on hyperactive behavior have also been examined by using dietary challenges. In these studies, children reported by their parents to respond positively to the Feingold diet were blindly "challenged" by the addition of food additives to the diet. Although some challenge studies have demonstrated a decrement in behavior when children are given food additives (Conners, 1980; Swanson and Kinsbourne, 1980), others revealed no detrimental effects of food additives (Conners, 1980; Weiss et al., 1980; Mattes and Gittelman, 1981). Several factors