Publication Detail

2012

Authors: Nigg JT, Lewis K, Edinger T, Falk M

Journal: ​Journal of the American Academy of Child & Adolescent Psychiatry (2012; 51(1): 86-97)

Supported by the ILSI North America Committee on Food and Chemical Safety

Objective: The role of diet and of food colors in attention-deficit/hyperactivity disorder
(ADHD) or its symptoms warrants updated quantitative meta-analysis, in light of recent
divergent policy in Europe and the United States. Method: Studies were identified through
a literature search using the PubMed, Cochrane Library, and PsycNET databases through
February 2011. Twenty-four publications met inclusion criteria for synthetic food colors; 10
additional studies informed analysis of dietary restriction. A random-effects meta-analytic
model generated summary effect sizes. Results: Restriction diets reduced ADHD symptoms
at an effect of g = 0.29 (95% CI, 0.07– 0.53). For food colors, parent reports yielded an effect size
of g = 0.18 (95% CI, 0.08–0.24; p = .0007), which decreased to 0.12 (95% CI, 0.01– 0.23; p less than .05)
after adjustment for possible publication bias. The effect was reliable in studies restricted to
food color additives (g = 0.21, 95% CI = 0.06–0.36) but did not survive correction for possible
publication bias and was not reliable in studies confined to Food and Drug Administration–
approved food colors. Teacher/observer reports yielded a nonsignificant effect of 0.07 (95% CI =
-0.03 to 0.18; p = .14). However, high-quality studies confined to color additives yielded a
reliable effect (g = 0.22, 95% CI = 0.10–0.41, p = .030) that survived correction. In
psychometric tests of attention, the summary effect size was 0.27 (95% CI = 0.07– 0.47; p = .007)
and survived correction. An estimated 8% of children with ADHD may have symptoms
related to synthetic food colors. Conclusions: A restriction diet benefits some children with
ADHD. Effects of food colors were notable were but susceptible to publication bias or were
derived from small, nongeneralizable samples. Renewed investigation of diet and ADHD is
warranted. J. Am. Acad. Child Adolesc. Psychiatry, 2012;51(1):86 –97. Key words: ADHD,
meta-analysis, synthetic food color additives, restriction diet

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