Food and Behaviour Research

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Does consumption of LC omega-3 PUFA enhance cognitive performance in healthy school-aged children and throughout adulthood? Evidence from clinical trials.

Stonehouse W. (2014) Nutrients. 6(7) 2730-58. doi: 10.3390/nu6072730. 

Web URL: View this and related abstracts via PubMed here. Free full text of this article is available online

Abstract:

Long-chain (LC) omega-3 PUFA derived from marine sources may play an important role in cognitive performance throughout all life stages. Docosahexaenoic acid (DHA), the dominant omega-3 in the brain, is a major component of neuronal cell membranes and affects various neurological pathways and processess. Despite its critical role in brain function, human's capacity to synthesize DHA de novo is limited and its consumption through the diet is important. However, many individuals do not or rarely consume seafood.

The aim of this review is to critically evaluate the current evidence from randomised controlled trials (RCT) in healthy school-aged children, younger and older adults to determine whether consumption of LC
omega-3 PUFA improves cognitive performance and to make recommendations for future research.

Current evidence suggests that consumption of LC 
omega-3 PUFA, particularly DHA, may enhance cognitive performance relating to learning, cognitive development, memory and speed of performing cognitive tasks. Those who habitually consume diets low in DHA, children with low literacy ability and malnourished and older adults with age-related cognitive decline and mild cognitive impairment seem to benefit most.

However, study design limitations in many RCTs hamper firm conclusions. The measurement of a uniform biomarker, e.g., % DHA in red 
blood cells, is essential to establish baseline DHA-status, to determine targets for cognitive performance and to facilitate dosage recommendations.

It is recommended that future studies be at least 16 weeks in duration, account for potential interaction effects of gender, age and apolipoprotein E genotype, include vegan/vegetarian populations, include measures of speed of cognitive performance and include brain imaging technologies as supportive information on working mechanisms of LC 
omega-3 PUFA.

FAB RESEARCH COMMENT:

As this review indicates, theory and experimental evidence support the proposal that an increased intake of long-chain omega-3 fatty acids may improve cognitive development and performance, but evidence from randomised controlled trials (RCT) still remains limited. 

Existing RCT evidence suggests that any such benefits are most likely to be evident in children with pre-existing behaviour and learning difficulties - e.g. from developmental conditions such as ADHD, dyspraxia/DCD or dyslexia. 

However, these kinds of diagnoses are all purely descriptive, each encompassing highly varied and overlapping populations.  Furthermore, as is well-established, there are numerous different possible 'causes' of such behaviour and learning difficulties (and these may all interact) - so nutrition is only one possible factor among many; and may be of little use in isolation if other factors are not addressed.

As this careful review emphasises, further, well-designed and well-conducted trials are still needed in order to identify those children most likely to benefit from omega-3 supplementation. Future studies need to pay particular attention to formulation and dosage of supplements (which varies considerably between trials), as well as including measures of blood fatty acid status, and other biomarkers that may help predict treatment response.

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