Objective: To examine the effects of sugar on the behavior or cognition of children by using meta-analytic techniques on reported studies.
Data sources: Studies were identified through a literature search of the MEDLINE and PsychINFO databases and the authors' files using sugar, sucrose, and attention deficit disorder as the search terms.
Study selection: Studies were required to (1) intervene by having the subjects consume a known quantity of sugar, (2) use a placebo (artificial sweetener) condition (3) blind the subjects, parents, and research staff to the conditions; and (4) report statistics that could be used to compute the dependent measures effect sizes.
Data extraction: Variables included publication year, study setting, subject type and number, gender, age, sugar and placebo type and dose, prior dietary condition, measurement construct, means and SDs for the sugar and placebo conditions, and direction of effect.
Data synthesis: Sixteen reports met the inclusion criteria for a total of 23 within-subject design studies. The weighted mean effect size and related statistics for each of the 14 measurement constructs revealed that although the range for these means was from -0.14 for direct observations and up to +0.30 for academic tests, the 95% confidence interval for all 14 mean effect sizes included 0.
Conclusion: The meta-analytic synthesis of the studies to date found that sugar does not affect the behavior or cognitive performance of children. The strong belief of parents may be due to expectancy and common association. However, a small effect of sugar or effects on subsets of children cannot be ruled out.