Omega-3 trial fails to reproduce benefits on child reading and memory seen in earlier study
These conclusions of the new trial, published in PLOS ONE, contradict those of a 2012 trial by the same researcher group - a collaboration between the Centre for Evidence based Intervention, Department of Social Policy and Intervention, University of Oxford and the University of Birmingham in the UK.
The earlier study found that compared with placebo, supplementation with algal-source DHA for 16 weeks improved parent-rated behaviour, and boosted reading progress in the poorest readers (those in the lowest fifth of the general population range).
In this second ‘DHA Oxford Learning And Behaviour’ (DOLAB) study, the researchers therefore focused again on those children whose initial reading performance was within the lowest quintile of the population for their age, recruiting 376 such children aged 7-9 years from 83 mainstream UK schools.
“In summary, this study did not replicate the original findings of significant, positive effects of omega-3 DHA on either learning or behaviour. No systematic adverse effects from the supplementation were observed,” wrote the researchers.
‘Same’ design, different findings
In their latest research paper, the scientists discuss some of the possible reasons for the contradictory findings from their two studies. Difficulties in replicating many, if not most, scientific research findings are now very well documented, explaining why good replication studies are so important.
Major changes in how reading is taught in UK schools occurred between the two trials, affecting the reading measures used. Additionally, other educational, economic and geographic differences hampered recruitment and data collection, the researchers elaborated.
The engagement of parents in the study may also have contributed to the different outcome.
“Parental involvement was more remote this time, leading to 50% missing data for behaviour change measures, despite the efforts of our highly experienced team,” said senior researcher Dr. Alex Richardson, from the University of Oxford. Richardson is also founder and director of the charity Food and Behaviour Research.
“It’s possible this affected compliance too; as although blood DHA increased significantly in supplemented children - from 1.6 to 2.9% on average - this remained sub-optimal for most, and less than expected given the dosage and duration,” Richardson added.
Blood EPA+DHA >4%, and ideally >8%, is thought optimal for cardiovascular health in adults, and most of this is DHA - the main structural omega-3 in both blood and brain cell membranes. However, meta-analyses of clinical trials to date suggest EPA may be more effective than DHA for some mental conditions – notably depression, but also possibly ADHD, explained Richardson.
Most studies showing benefits of ‘omega-3’ for child behaviour and learning have used fish oils containing both EPA and DHA – and some also omega-6 GLA and AA. Determining optimal fatty acid formulations and dosages requires further research – but according to Dr Richardson, these new findings also suggest a need to re-focus on the specific developmental conditions in which fatty acid deficiencies and imbalances have long been implicated.
“Increasing evidence indicates the relative lack of omega-3 in typical modern, western-type diets is suboptimal for physical and mental health – but it makes no sense to suggest everyone is equally affected by this – especially for outcomes like reading.” Richardson added.
“The best evidence for benefits from supplementation comes from more carefully targeted and theory-driven studies – like our Oxford-Durham study of children with Developmental Coordination Disorder, or for conditions like ADHD, dyslexia and the autistic spectrum, and some forms of depression. We also know these conditions have their origins in early life and usually compound over time, so earlier interventions also need more investigation.”
Results in perspective
Putting the null findings of a single trial in perspective, Dr. Harry Rice, Vice President of Regulatory and Scientific Affairs, Global Organisation for EPA and DHA Omega-3s (GOED) said:
“This is an important area of research and not worth deserting just because the results from one study weren't replicated
“I’ve always said that omega-3 are not a panacea, but ‘don't throw the baby out with the bathwater’ because they're incredibly beneficial to human health!
“Throughout the life cycle, there are many reasons to eat fatty fish rich in EPA/DHA and/or take high quality EPA/DHA supplements. Most people that are eating fatty fish and taking supplements are doing so as part of a healthy lifestyle, not to treat a specific issue/ailment. Despite the current results, increasing omega-3 intake is a good idea for reasons that have been substantiated with decades of research,” Rice concluded.
Source: PLOS ONE
Published online: 20 February 2018. DOI: 10.1371/journal.pone.0192909
“Docosahexaenoic acid for reading, working memory and behaviour in UK children aged 7-9: A randomized controlled trial for replication (the DOLAB II study)”
Authors: Paul Montgomery , Thees F. Spreckelsen, Alice Burton, Jennifer R. Burton, Alexandra J. Richardson.