ny Biological Explanation to Support an Effect of Defined Diets on Hyperactivity?
Only one specific biological explanation has been proposed--that the food dye erythrosine (FDC Red No. 3) inhibits neurotransmitter uptake. Experimental studies first suggested that Red No. 3 could inhibit the uptake of dopamine and other neurotransmitters in vitro. If true, this observation presented a mechanism by which this food additive could affect behavior. However, more recent studies suggested that this effect of Red No. 3 was the result of nonspecific interactions, and these studies raised doubts about whether Red No. 3 would affect the behavior of the intact organism. In support of this latter idea, data from three groups using the laboratory rat found that Red No. 3 caused no increase in activity or had effects only at near-lethal doses. Additionally, one study in children found that the minor behavioral changes apparently caused by challenge with a mixture of food colors were a result of food colors other than Red No. 3.
Despite these negative preliminary data, it was recognized that further research, especially pharmacokinetic studies, were needed before these questions could be answered conclusively about Red No. 3 or other dietary agents. Moreover, other explanations of why a defined diet lacking food dyes, flavorings, preservatives, salicylates, and major food antigens may be beneficial can only be suggested. Direct toxic effects, idiosyncratic reactions to such agents, and hypersensitivity (allergic) responses (both IgE-mediated and non-IgE-mediated) to food antigens also could cause the observed findings. This might be by direct effects on the central nervous system or by indirect effects on other systems. However, no direct evidence for the operation of these mechanisms in treated patients is available at this time.
Placebo effects and observer bias inherent to any major therapeutic intervention (when not controlled by appropriate blinded procedures), may also account for some of the reported benefits.
If Defined Diets Are Effective, How and Under What Circumstances Should They Be Employed?
Case reports of a subset of responding patients presented to this panel by parents and physicians documented improvement in the hyperactive child's condition with the use of defined diets. Because insufficient evidence is available to permit identification beforehand of this small group of individuals who may respond and to determine under what circumstances they may derive benefits, the Panel cannot answer this question unequivocally.
The Panel believes the defined diets should not be universally used in the treatment of childhood hyperactivity at this time. However, the Panel recognizes that initiation of a trial of dietary treatment or continuation of a diet in patients whose families and physicians perceive benefits, may be warranted. A defined diet should not be initiated until thorough and appropriate evaluation of the children and their families and full consideration of all traditional therapeutic options (described in the Introduction) have taken place.
The ability to describe "defined diets" precisely and to ensure proper and effective clinical use, to measure compliance, and to design studies and compare the findings from one study to another depends upon making available to consumers and investigators food and food products that are completely labeled. The Panel understands that existing law does not require identifying on the label, completely and accurately, all ingredients in food. The Panel, therefore, recommends changes in the law to require the listing on labels of all ingredients of food and food products, and that this label include substances that may migrate from wrappers and containers that come in contact with foods.
The Panel also believes that special attention must be given to individual cultural, ethnic, and socioeconomic factors to ensure the proper implementation of the diet. Since the defined diets differ from traditional dietary patterns, it is the physician's responsibility to be specific and impart the