In a column last month I explored the link between dementia and a substance called homocysteine, and suggested that higher intakes of certain nutrients may lower the levels of this blood constituent and help keep our wits about us as we age. October also saw the publication of a study in the Archives of Neurology which linked the eating of fish with a significantly reduced rate of brain function decline associated with ageing. This research has come on the back of a wave of other studies which have found that the consumption of fish appears to help keep dementia and impaired brain function at bay.

Research linking fish eating with some preservation of our mental faculties has stimulated scientists to look for what it is in fish that might be good for the brain. Some researchers have looked to the so-called omega-3 fats, found most abundantly in ‘oily’ fish such as salmon, mackerel, herring and sardine, for an explanation. The omega-3 fats found in fish come in two main forms; docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). While DHA is important for brain development and structure, EPA seems to have a more important influence on the day-to-day running of the brain.

The fundamental roles these fats appear to play in brain function mean that they have the potential not only to combat dementia, but mental illness too. Studies show, for instance, individuals with low levels of omega-3 fats in their bloodstreams are at generally increased risk of depression and schizophrenia. This finding has prompted researchers to assess the effect of supplementing omega-3 fats in individuals suffering from depression or schizophrenia.

Partly because of its role in the smooth running of the brain, EPA has been the focus of the bulk of such research. In most of these studies, EPA has been given in addition to conventional medicine. Satisfyingly, the majority of this research has shown that EPA has the ability to bring significant reductions in depressive and schizophrenic symptoms. The evidence is strong enough, I think, for the supplementation of EPA to be considered in those suffering from depression or schizophrenia, though I recommend that this be done under medical supervision.

The dose of EPA that has been found to be necessary to bring benefit in mental disorder appears to be in the region of 1000 – 2000 mg (1 – 2 g) per day. Some benefit is likely to be had by the inclusion of oily fish in the diet a couple of times a week. However, supplementation with EPA generally provides a practical way to get assured amounts of EPA into the body on a regular basis. The apparent potential omega-3 fat has to promote normal mental function does gives credence to the reputation fish has as the ultimate brain food.

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