A meta-analysis of blood fatty acids in people with learning disorders with particular interest in arachidonic acid

FAB RESEARCH COMMENT:

This study found significantly lower blood concentrations of omega-6 AA, as well as omega-3 DHA, in children with various behaviour and learning disorders compared with controls. This finding was from a meta-analysis combining data from published studies to date (involving over 400 children in total).

Increasing evidence indicates that fatty acid abnormalities can play a role in childhood behaviour and learning difficulties such as ADHD, dyslexia, dyspraxia and autistic spectrum disorders.

In blood fatty acid studies, low concentrations of the long-chain omega-3 fatty acids (EPA and DHA) have most commonly been reported. This is in keeping with the apparent benefits of dietary supplementation with fish oils (which contain these omega-3) shown in some clinical trials of children with these kinds of conditions. However - as this review points out, the most successful trials in this area have also included some omega-6 AA, as well as omega-3 EPA/DHA, in the active treatment formulations.

To date, very little attention has been paid to the potential role of the main omega-6 fatty acid - arachidonic acid (AA) - in child behaviour and learning difficulties.  Like omega-3 DHA, omega-6 AA is a key component of brain and nerve cell membranes, and (like EPA and DHA) it also gives rise to numerous other substances that help to regulate blood flow, hormonal balance, immune function, gene expression and many other aspects of cell signalling in the body and brain.

Modern western-type diets are very rich in the short-chain omega-6 (linoleic acid, or LA), found in vegetable oils. And because this can (at least in theory) be converted within the body to omega-6 AA, it is generally assumed that AA deficiencies are unlikely.  

The low AA levels reported here in children with behaviour and learning difficulties call that assumption into question. 

Individual differences in conversion efficiency, and/or other factors (such increased loss via oxidative stress), may affect dietary needs for AA.  Deficiencies of this key omega-6 have already been implicated in some mental health conditions such as schizophrenia.

In addition to detailed analyses of the blood fatty acid findings to date, this paper also provides a summary of treatment studies in this area, and a comprehensive, detailed review of what is currently known about dietary sources of, and requirements for, arachidonic acid.