About a decade ago there was a lot of excitement about using fish oils in the management of mental health, so much so even the American Psychiatric Association developed recommendations suggesting that people with mood, impulse control & psychotic disorders should all consume 1g EPA + DHA per day… but then what happened? Ask most health professionals (GPs, psychiatrists, naturopaths & nutritionists alike) today whether fish oils are their first choice in mental health nutritional interventions and you’ll frequently get a, ‘No’ and I include myself in that.
Let’s retrace our steps to find out how we got here. The epidemiological evidence linking low omega 3 intake to myriad mental health problems in terms of susceptibility, incidence and severity is almost overwhelming. For example, depression rates are 10 times higher in countries with limited seafood intake and post-partum depression 10-50 times higher (Kendall-Tackett, 2010).
Noaghiul & Hibbeln postulated that countries where individuals consumed less than ≈ 450-680g of seafood per person per week demonstrated the highest rates of affective disorders (2003). One study of 33 000 women with low omega-3 intake were found to have an increased risk of psychotic symptoms (Goren & Tewksbury 2011) and it goes on. Then, we have other evidence also pointing in the direction of fish oils, such as the general consensus that excess unchecked inflammation is evident in many mental health conditions (Maes et al 2013). Numerous intervention studies using fish oils as stand-alone or adjunctive treatments have been published. Interventions have included high dose omega 3 (no specific EPA/DHA breakdown), EPA alone, ethyl-EPA, high DHA, blends with high DHA:EPA ratio, flaxseed oil etc. etc.
These studies are quickly followed by the systematic reviews, meta-analyses etc. which almost invariably conclude that supplementation with fish oils isn’t effective – or more correctly, based on this terrible mish–mosh of evidence no firm conclusions can be reached.
Take the Cochrane Review on the use of fish oils in Bipolar Disorder for example, which based their negative conclusion on the results of one study (Frangou et al 2006), while > 23 others failed to meet their inclusion criteria (Montgomery & Richardson 2008).
The big take home message should actually be: Fish oils ain’t fish oils!
If you understand some of the key structural & biochemical differences between EPA (precursor to eicosanoids, able to generate DHA, little structural contribution to the brain) and DHA (major structural brain fat, precursor to the docosanoids including resolvins, mild reuptake inhibitor of 5HT and DOP), the superior bioavailability of triglyceride forms over ethyl esters and the seriously limited ability of humans to convert plant omega 3 precursors to the LCPUFAs, then you can start to see your way through the research mess and step away from the broad brush stroke conclusions of the Cochrane review and similar.
Check out some of the better written and more insightful reviews – especially this one by Sublette (2011) which found that in successful treatment of depression fish oil supplements must have >60% EPA compared with DHA and read her theories on this. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3534764/ So we need to get reading and get clearer about which specific omega 3 fatty acid or blend (and in what ratios) works for which mental health problem – its definitely not a case of one-size-fits-all – do your homework and pick your products well and most importantly let’s not throw the fish out with all that fishy research!