Attention Deficit Hyperactivity Disorder: Nutritional Considerations

The role of diet in ADHD has been controversial ever since it was first proposed in the book Why Your Child Is Hyperactive, by pediatrician Ben Feingold, M.D.⁹ Dr. Feingold demonstrated that the removal of synthetic colorings, flavorings, and preservatives from the diet led to a marked improvement in many children. (Feingold suspected a much wider array of dietary sensitivities, but those 3 were the easiest to study.) Later researchers failed to replicate these effects.

However, subsequent studies have reasserted the role of diet, suggesting that the list of offending agents may go beyond the food dyes, flavorings, and preservatives that were originally studied. Children with ADHD often have an allergic or other hypersensitive response to artificial colors, flavors, or preservatives,¹⁰ and recent studies suggest that a histamine response may underlie ADHD symptoms in some children (see below). In addition, some studies have suggested a contributory role of nutrient–poor meals and snacks.¹⁰ Such diets may contribute to the deficiency of nutrients (eg, iron and zinc) that have been documented in children with ADHD¹¹ and that are known to be required for neurotransmitter production.

The following nutritional factors are under study for their effect on ADHD:

Diets free of artificial flavorings, colors, and common allergens. At least 8 controlled studies have demonstrated significant behavioral improvement on oligoantigenic diets compared with regular diets, or behavioral deterioration on a placebo–controlled challenge with foods suspected of aggravating symptoms. In one of these, parental reports indicated that more than half the subjects exhibited a reliable improvement in behavior.¹² Typical oligoantigenic diets used previously included only lamb, chicken, potatoes, rice, banana, apple, cabbage, cauliflower, Brussels sprouts, broccoli, cucumber, celery, carrots, parsnip, salt, pepper, calcium, and vitamins.¹³ The therapeutic basis for such a regimen may lie in an allergic response (ie, histamine production) to artificial colors, flavors, and dyes. Histamine is a neurotransmitter; antagonism of its actions improves cognitive performance. Of note, the antihistamine diphenhydramine (Benadryl) was once a treatment for ADHD, although it was not as effective as stimulants. Other histamine receptor antagonists are currently being evaluated for potential application in ADHD.¹⁴

A meta–analysis of double–blind, placebo–controlled trials concluded that artificial food colors contribute one–third to one–half of the behavioral deterioration that would be observable when hyperactive children are taken off psychostimulants.¹⁵

Omega–3 fatty acids. Both omega–3 and omega–6 fatty acids have been reported to be lower in children with ADHD compared with other children, and limited data suggest that certain fatty acids (eg, eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA)) can affect behavior. However, clinical trials of polyunsaturated essential fatty acids in children with ADHD have produced inconsistent results.¹³ Of 6 published placebo–controlled trials of polyunsaturated essential fatty acids, 2 with gamma–linolenic acid were equivocal, 1 with DHA was negative, and 3 with a combination of GLA, EPA, and DHA were positive on some measures.¹³

Zinc. As a cofactor for neurotransmitters, zinc influences regulation of γ–aminobutyric acid (GABA), serotonin, and dopamine, all of which may play roles in ADHD.¹⁶ Poor zinc status, a common occurrence, can delay cognitive development and has been found with greater frequency in hyperactive children, compared with controls.¹⁶ Zinc status has been reported in a small sample to correlate with response to amphetamine treatment,¹⁶ and controlled clinical trials in the Middle East, an area of zinc deficiency, support the possibility that supplemental zinc (55–150 mg ZnSO4/day) may improve response to methylphenidate¹⁷ or improve symptoms of hyperactivity and impulsiveness when used as monotherapy.¹⁸ However, these reports leave questions about sample retention and data analysis, and further controlled clinical trials are required.

Aspartame or sucrose restriction and mineral supplements. Controlled trials of sugar–restricted diets found no effect on behavioral symptoms in ADHD, even in children thought to be sugar–sensitive.^13,19 Deficiency of several minerals (iron, copper, zinc, calcium) may influence neurotransmission in the central nervous system, and several studies have demonstrated mineral deficiencies in children with ADHD. However, controlled studies have not established a clear benefit of supplementation in individuals with ADHD.¹¹ Similarly, studies have not supported a causal role for aspartame in ADHD.²⁰

Orders

See Nutritional Requirements throughout the Life Cycle chapter.

What to Tell the Family

ADHD can impair learning, work performance, and social relationships. However, several treatments are available. Although many parents have understandable concerns about drug therapy, medications are highly effective and generally provide rapid and dramatic relief. Other options––behavioral treatment, special educational programming, and, for a subset, oligoantigenic diet––may be tried separately or in combination with medication.