Docosahexaenoic acid for reading, working memory and behavior in UK children aged 7-9: A randomized controlled trial for replication (the DOLAB II study)

BACKGROUND: Omega-3 fatty acids are central to brain-development of children. Evidence from clinical trials and systematic reviews demonstrates the potential of long-chain Omega-3 supplementation for learning and behavior. However, findings are inconclusive and in need of robust replication studies since such work is lacking. OBJECTIVES: Replication of the 2012 DOLAB 1 study findings that a dietary supplementation with the long-chain omega-3 docosahexaenoic acid (DHA) had beneficial effects on the reading, working memory, and behavior of healthy schoolchildren. DESIGN: Parallel group, fixed-dose, randomized (minimization, 30% random element), double-blind, placebo-controlled trial (RCT). SETTING: Mainstream primary schools (n = 84) from five counties in the UK in 2012–2015. PARTICIPANTS: Healthy children aged 7–9 underperforming in reading (<20(th) centile). 1230 invited, 376 met study criteria. INTERVENTION: 600 mg/day DHA (from algal oil), placebo: taste/color matched corn/soybean oil; for 16 weeks. MAIN OUTCOME MEASURES: Age-standardized measures of reading, working memory, and behavior, parent-rated and as secondary outcome teacher-rated. RESULTS: 376 children were randomized. Reading, working memory, and behavior change scores showed no consistent differences between intervention and placebo group. Some behavioral subscales showed minor group differences. CONCLUSIONS: This RCT did not replicate results of the earlier DOLAB 1 study on the effectiveness of nutritional supplementation with DHA for learning and behavior. Possible reasons are discussed, particularly regarding the replication of complex interventions. TRIAL REGISTRATION AND PROTOCOL: www.controlled-trials.com (ISRCTN48803273) and protocols.io (https://dx.doi.org/10.17504/protocols.io.k8kczuw)