The second of a four-part series on nutritional interventionsexamines evidence of a salicylate-elimination diet for ADHD.
DR. BRAGANZA is an assistant professor of pediatrics at Children's Hospital at Montefiore Albert Einstein College of Medicine, Bronx, NY.
DR. GALVEZ is an assistant professor of pediatrics and of community and preventive medicine at Mount Sinai School of Medicine, New York, NY.
DR. OZUAH is a professor of pediatrics and interim university chairman at Children's Hospital at Montefiore Albert Einstein College of Medicine, Bronx, NY.
The effect of nutrition on mood and behavior is well known; certain protein-rich foods such as meat, cheese, and eggs contain amino acids that are precursors of neurotransmitters such as serotonin, dopamine, and norepinephrine. These precursors cross the blood-brain barrier and, through complex interactions, are synthesized into neurotransmitters. These neurotransmitters are hypothesized to directly affect behavior and cognition.2
Enter the Feingold diet
The late pediatric allergist Benjamin Feingold, MD, was the leading proponent of a nutritional basis for hyperactivity in children.2 Working with children who exhibited sensitivity to aspirin, foods, and food additives, Feingold described physical reactions and behavioral changes-such as inattention-that he considered to be precursors of hyperactivity and learning disability. Feingold suggested a causal relationship between the increased use of artificial colorings and flavorings in food products and the incidence of hyperactivity and learning disability.7,8 Based on his observations, Feingold developed a salicylate elimination diet that prohibited not only the salicylate-containing compounds aspirin and aspartame, and foods containing dyes and preservatives, but also apples, berries, grapes, oranges, peaches, plums, cucumbers, and tomatoes. These fruits and vegetables were thought to form chemicals similar to acetylsalicylic acid, which contained a so-called salicylate radical. Dr. Feingold did not, however, specify which of the salicylate chemicals could produce an effect, and at what dosage.8 Feingold claimed that the schoolwork of an ADHD child who was on this diet would improve, and that hyperactive behaviors would diminish.7,8
Does the diet have an effect?
Despite anecdotal reports and uncontrolled studies conducted in the 1970s that continued to suggest a relationship between elimination diets and behavior, controversy developed within the scientific community over Feingold's claims.2,8 The most significant concern was a lack of prospective, randomized, controlled trials of the effect of salicylate compounds on behavior: Which, if any, specific chemicals are responsible for the effect, and in what concentrations? A second concern was that parents would alter their child's diet-thereby potentially influencing growth and development-based on anecdotal observations alone. These concerns led to the establishment of the National Advisory Committee on Hyperkinesis and Food Additives, which recommended that the Nutrition Foundation study the effects of the diet with food challenge.2
Early food challenge studies demonstrated no change in behavior when a child was on the Feingold diet.9 A later review of 13 double-blind, placebo-controlled trials in well-defined study population of 240 children demonstrated that only 1% of children exhibited a consistent improvement of symptoms while on the diet.8 No change in behavior was reported in more than 90% of children challenged with standardized food dyes.8 These data provided limited support for any beneficial effect of the Feingold diet except in a small percentage of children with a behavior disorder.