The Influence of DHA on Language Development: A Review of Randomized Controlled Trials of DHA Supplementation in Pregnancy, the Neonatal Period, and Infancy

Abstract

This review summarizes randomized controlled trials (RCTs) assessing the effect of docosahexaenoic acid (DHA) supplementation in the first 1000 days on child language. Six databases were searched and RCTs were included if they involved supplementation with DHA during pregnancy, to preterm infants, or during the postpartum period, included a placebo group with less or no DHA, and reported a language outcome. We included 29 RCTs involving n = 10,405 participants from 49 publications. There was a total of 84 language measures at ages ranging from 3 months to 12 years. Of the 84 assessments, there were 4 instances where the DHA group had improved scores, and 2 instances where the DHA group had worse scores (with the majority of these significant effects found within one RCT). The remaining comparisons were null. A few RCTs that included subgroup analyses reported (inconsistent) effects. There was limited evidence that DHA supplementation had any effect on language development, although there were some rare instances of both possible positive and adverse effects, particularly within population subgroups. It is important that any subgroup effects are verified in future trials that are adequately powered to confirm such effects.

The Influence of Omega-3 Long-Chain Polyunsaturated Fatty Acid, Docosahexaenoic Acid, on Child Behavioral Functioning: A Review of Randomized Controlled Trials of DHA Supplementation in Pregnancy, the Neonatal Period and Infancy

“…Our review of the effect of a DHA intervention in the first 1000 days on behavioral development has a similar conclusion to reviews of DHA supplementation over the same period on cognition, motor or visual development [ 76 ], or language abilities [ 78 ]. Additionally, several reviews and meta-analyses of more specific windows within the first 1000 days have identified little, if any evidence of benefits of DHA supplementation for brain development [ 68 , 69 , 70 , 71 , 72 , 74 , 125 ].…”

“…Additionally, several reviews and meta-analyses of more specific windows within the first 1000 days have identified little, if any evidence of benefits of DHA supplementation for brain development [ 68 , 69 , 70 , 71 , 72 , 74 , 125 ]. Our previous review of DHA interventions and subsequent language abilities revealed that whilst the majority of language measures were null, four suggested a benefit and two suggested an adverse effect [ 78 ]. Differences in findings between RCTs of DHA supplementation and observational studies of dietary sources of DHA could be due to a number of reasons, such as additional nutrients present in foods naturally rich in DHA and the inherent confounding in observational studies due to the difficulty in adjusting for complex confounding factors [ 67 ].…”

“…Where only abstracts were accessible, such as from conference proceedings, these were included. Reference lists of included articles returned by the search were checked for other eligible articles as well as reference lists of other reviews [ 52 , 68 , 69 , 71 , 72 , 76 , 78 ]. PubMed was set up to email new publications identified by the search on a monthly basis with new articles added to the review up until acceptance of the manuscript.…”

“…There has been no consideration given to collating and considering the evidence for DHA supplementation in early life to effect development of child behavior as a whole [ 68 , 69 , 70 , 71 , 72 , 74 , 76 ], despite the substantial interest in the role of DHA for behavioral problems [ 10 , 52 , 53 , 57 , 58 , 59 , 77 ]. Furthermore, whilst adequate DHA is likely to be important throughout the whole of the first 1000 days, only two reviews to date have attempted to synthesize the evidence from RCTs conducted across this period and behavior was not a reported outcome of either review [ 76 , 78 ]. Given the biological plausibility for the role of DHA in behavioral functioning as well as the increasing body of evidence supporting the importance of this role, further research is warranted [ 10 ].…”

The Influence of Prenatal DHA Supplementation on Individual Domains of Behavioral Functioning in School-Aged Children: Follow-Up of a Randomized Controlled Trial

“…Numerous randomized controlled trials (RCTs) have attempted to evaluate the effect of providing supplemental DHA to pregnant women on child brain development through performance-based measures such as intelligence quotient tests. Multiple reviews of these RCTs have concluded very little evidence of an effect of a DHA intervention on cognition [ 15 , 16 , 17 , 18 ], executive functioning (higher-order cognitive abilities) [ 15 , 18 , 19 ], motor [ 15 , 16 , 17 , 18 ], or language abilities [ 15 , 16 , 17 , 18 , 20 ]; however, a recent review suggested some behavioral effects [ 21 ].…”