Increasingly diet is being linked to the health of the brain. In particular, consumption of the typical Western diet may increase the risk of neurological age related degeneration. The reason for this may be numerous, but certainly one factor that is currently being researched is the ability of the Western diet to produce pro-inflammatory effects in brain tissue. Such inflammation may lead to excessive free radical generation, and this oxidative stress may cause degradation of the delicate unsaturated fats that predominate in the brain. Fish oils and other sources of omega-3 fatty acids may protect the brain form d'generation because they increase the eicosapentaenoic acid content of cell membranes. This eicosapentaenoic acid acts as a reservoir for the synthesis of anti-inflammatory series 3 eicosanoids that may decrease the inflammation in the brain tissue. However, as well as eicosanoids, docosanoids may also play a role.
Docosanoids are short lived hormone molecules derived from docosahexaenoic acid. Docosahexaenoic acid is a component of fish oil and is also able to be synthesised from other sources of omega-3 fatty acids. Evidence suggests that docosahexaenoic acid accumulates in cell membranes, and is particularly concentrated in the membranes of neurones in the central nervous system. Here the fatty acid acts as a reservoir for the production of docosanoids, short lived chemical messengers that may regular neurotransmission and other neuronal functions. For example the docosanoid neuroprotectin D1 has been shown to inhibit the apoptosis of neurones exposed to oxidative stress. Docosanoids may also be involved in the maintenance of correct serotonin metabolism and aid in memory and learning. The presence of docosahexaenoic acid is fish therefore justifies the classification of fish as a brain food.