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

Montgomery P, Spreckelsen TF, Burton A, Burton JR, Richardson AJ. (2018) PLOS One Feb 20, https://doi.org/10.1371/journal.pone.0192909

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Abstract:

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 (<20th 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)

FAB RESEARCH COMMENT:

This study did not confirm earlier findings from the original DHA Oxford Learning and Behavior (DOLAB) Study, which found that supplementation with algal-source omega-3 DHA vs placebo led to some benefits for children aged 7-9 years from the UK general school population who were initially underperforming in reading for their age.

In that trial, reductions in ADHD-type symptoms were found for the full sample of 362 children studied (whose initial reading placed them in the lowest 33% of all readers), while improved reading was seen only in the poorest readers (those scoring in the lowest 20% of the general population range - a pre-planned subgroup analysis). For details, see:

Richardson et al 2012 - Docosahexaenoic Acid for Reading, Cognition and Behavior in Children Aged 7-9 Years: A Randomized, Controlled Trial (The DOLAB Study)

Significant improvements in children's sleep (a secondary measure) were also found for those children with initial sleep problems (which was over half the study sample). See:

Montgomery Et Al 2014 - Fatty Acids And Sleep In UK Children: Subjective And Pilot Objective Sleep Results From The DOLAB Study - A Randomized Controlled Trial

In the current study - which involved 376 children from the lowest 20% of all readers - measures of sleep could not be included owing to resource constraints. For the primary outcomes of reading, working memory, or behaviour (ADHD-type symptoms), results showed no group differences.

Possible reasons for this failure to replicate the DOLAB 1 findings are discussed in the article, which is open access.

For more information on clinical trials of omega-3 in children, see also: