"Another theory was that refined sugar and food additives make children hyperactive and inattentive. As a result, parents were encouraged to stop serving children foods containing artificial flavorings, preservatives, and sugars. However, this theory, too, came under question. In 1982, the National Institutes of Health (NIH), the Federal agency responsible for biomedical research, held a major scientific conference to discuss the issue. After studying the data, the scientists concluded that the restricted diet only seemed to help about 5 percent of children with ADHD, mostly either young children or children with food allergies.
ADHD Is Not Usually Caused by: too much TV, food allergies, excess sugar, poor home life, poor schools."
"Some controlled, double-blind studies indicate that these diets are only occasionally efficacious. Apparent discrepancies between some clinical impressions of efficacy and much of the available scientific evidence prompted the scheduling of this Consensus Development Conference. ...
Parents and other observers have frequently reported dramatic improvements in many hyperactive children during uncontrolled trials of various defined diets. However, such dramatic improvements were not observed in a number of controlled trials reported at the conference.
While differences and inadequacies in the design of the controlled trials make analysis difficult, these studies did indicate a limited positive association between "the defined diets" and a decrease in hyperactivity. Some hyperactive children demonstrated less evidence of hyperactivity on defined diets, or modifications thereof, than on an appropriate control diet. Such decreases involved only a small proportion of patients; furthermore, the decreases in hyperactivity were not observed consistently. Studies also indicated that some hyperactive children on a defined diet experienced an increase in hyperactivity when given moderate doses of artificial food dyes, and did not experience similar increases after receiving a placebo. This increase in hyperactivity was also experienced by only a small group of patients, and the increase was not consistently reported by teachers, parents, and other observers.
Clinical observations also indicated that children who were successfully managed on a defined diet experienced hyperactivity after dietary noncompliance. Controlled challenge studies have primarily involved the administration of food dyes to children, but have not included other food flavors or preservatives that are allegedly implicated in the causation of hyperactivity. Therefore, these controlled challenge studies do not appear to have addressed adequately the role of diet in hyperactivity."