In 1973, Benjamin Feingold, M.D., a pediatric allergist from California, proposed that salicylates, artificial colors, and artificial flavors caused hyperactivity in children. (Hyperactivity is now medically classified as an attention deficit disorder [ADD] or attention deficit hyperactivity disorder [ADHD]). To treat or prevent this condition, Feingold suggested a diet that was free of such chemicals. Feingold's followers now claim that asthma, bedwetting, ear infections, eye-muscle disorders, seizures, sleep disorders, stomach aches, and a long list of other symptoms may respond to the Feingold program and that sensitivity to synthetic additives and/or salicylates may be a factor in antisocial traits, compulsive aggression, self-mutilation, difficulty in reasoning, stuttering, and exceptional clumsiness. The "Symptom Checklist" on the Feingold Association of the United States (FAUS) web site includes many additional problems.
Adherence to the Feingold diet requires a change in family lifestyle and eating patterns, particularly for families who prepare many meals from "scratch." Feingold strongly recommended that the hyperactive child help prepare the special foods and encouraged the entire family to participate in the dietary program. Parents are also advised to avoid certain over-the-counter and prescription drugs and to limit their purchases of mouthwash, toothpaste, cough drops, perfume, and various other nonfood products to those published in FAUS's annual "Food List and Shopping Guide."
Current recommendations advise a two-stage plan that begins by eliminating artificial colors and flavors; the antixoidants BGA, BHT, and TBHQ; aspirin-containing products; and foods containing natural salicylates. If improvement occurs for four to six weeks, certain foods can be "carefully reintroduced" one at a time . However, the Feingold Cookbook (published in 1979 but still in print) warns:
A successful response to the diet depends on 100 percent compliance. The slightest infraction can lead to failure: a single bite or drink can cause an undesirable response that may persist for seventy-two hours or more. 
Many parents who have followed Feingold's recommendations have reported improvement in their children's behavior. FAUS, which has local chapters throughout the country, claims that fidgetiness, poor sleeping habits, short attention span, self-mutilation, antisocial traits, muscle incoordination, memory deficits, asthma, bedwetting, headaches, hives, seizures, and many other problems may respond to the Feingold program . But carefully designed experiments fail to support the idea that additives are responsible for such symptoms the the vast majority of children. Most improvement, if any occurs, appears related to changes in family dynamics, such as paying more attention to the children. Experts have also noted that the foods recommended in Feingold's 1975 book Why Your Child Is Hyperactive included some that were high in salicylates and excluded others that were low in salicylates.
In the ideal experiment, children whose behavior seems to have improved on the Feingold diet are kept on the diet but are periodically challenged with one or more suspected substances. Under ideal circumstances, the procedure should be double-blind, so that neither the participants nor the experimenters know when the substances are being administered. In 1980, an expert review team assembled by the Nutrition Foundation concluded:
Based on seven studies involving approximately 190 children, there have been no instances of consistent, dramatic deterioration in behavior in hyperactive children challenged, under double-blind conditions, with artificial food colorings. . . . There are three . . . exceptions to these generally negative conclusions, but, in all three cases, the deterioration is reported by the mother with no other objective, confirming evidence available. . . . Without the confirming evidence of objective tests and/or outside observers, even these exceptions cannot be considered as definite evidence that there may be an occasional, genetically determined, sensitivity to food colorings. Though one cannot prove that no such children will be found, sufficient numbers of highly selected children have been studied to feel confident that such specific sensitivity, if found, will be rare.
These negative findings stand in sharp contrast to the 32-60 percent of children reported by Dr. Feingold and others to improve dramatically under non-blind conditions without the use of placebo controls. 
In 1983, the review team's co-chairman and another colleague reviewed additional studies and concluded that no more than 2% of children respond adversely to dye additives, and even that statistic was questionable . Since that time, experimental findings have been mixed. Some researchers have reported no effect [6-7] and some have reported worsening behavior during challenge experiments [8-10]. However, it remains clear that the percentage of children who may become hyperactive in response to food additives is, at best, very small. Sugar and aspartame (an artificial sweetener) have also been blamed for hyperactivity, but well-designed studies have found no evidence supporting such claims [11-13].
The claims of Feingold advocates have steadily expanded, and some resemble those made by clinical ecologists. The 1986 Feingold Handbook for example, states that "sensitivity to synthetic chemicals in the food or environment, or to some natural salicylates" can cause adults to suffer from nervous habits, chronic fatigue, impulsiveness, poor self-image, poor coordination, mental and physical sluggishness, temper flare-ups, headaches, depression, erratic sleep patterns, and a "tendency to interrupt." These claims are absurd.
The September 1992 issue of the Feingold Association's newsletter, Pure Facts, claimed that teachers and children have been noted to suffer from the effects of chemicals used in construction, furnishing, housekeeping, maintenance, renovation, pest control, food service, and classroom activities at their schools. An article titled "The Sick Building Syndrome" stated that one child was repeatedly disciplined for reacting to his teacher's perfume, another child became abusive toward his mother because of the school's newly painted lunchroom, and that yet another child required tutoring because of a very bad reaction to a leak in the school's oil furnace. Although exposure to significant levels of chemical fumes in poorly ventilated buildings can make people ill, such instances are rare. The idea that perfume causes misbehavior is nonsensical.
Because the Feingold diet does no physical harm, it might appear to be helpful in some instances. However, the potential benefits should be weighed against the potential harm of (1) teaching children that their behavior and school performance are related to what they eat rather than what they feel, (2) undermining their self esteem by implanting notions that they are unhealthy and fragile, (3) creating situations in which their eating behavior or fear of chemicals are regarded as peculiar by other children, and (4) depriving them of the opportunity to receive appropriate professional help.