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Cases of Depression Soar - Is it What We're (Not) Eating?

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An analysis of NHS figures, released this week by data experts SSentif, revealed that the number of people living with depression in England has soared by nearly half a million in the last three years, with the total number standing at almost 5 million.

Inevitably, this has been accompanied by a large increase in the number of prescriptions for anti-depressant drugs. With official figures such as these likely to be merely the tip of the iceberg, just quite how much worse the actual situation is, is anyone's guess.

Am I surprised? Not in the slightest. The writing was already on the wall and this is just more evidence of the growing burden of mental health problems society faces. As discussed recently in Nature , across 30 European countries, in a typical year, it's estimated that around 165 million people - 38% of the population of these countries - will have a fully developed mental illness. When it comes to major depression, across these 30 countries, the estimated number of people affected was 30 million -- making it the single greatest burden of all human diseases.

Certainly, mental health problems, and depression in particular, are undoubtedly complex, multi-factorial conditions. But the bit I'm interested in - and think more people should take seriously - is the extent to which our modern day diets are messing with our brains. To offer a window into this paradigm of thinking, I'm going to make reference to a particular constituent of our diet - omega-3 fish oils. Firstly (and famously), there's a strong correlation between a nation's fish consumption and the prevalence of depression [1], meaning countries with a high intake of fish (for example, Japan) have much lower rates of depression than countries with a low intake (such as the UK).

Whilst tantalising, this type of data is mere correlation, subject to any number of 'confounders'. However, the fact that omega-3 fish oils (EPA and DHA) are critical for the structure and function of the brain, and play a role in how neurotransmitters work, does add biological plausibility. Then, we find that patients with depression have lower levels of omega-3 [2], and not only that, the lower the level of omega-3, the worse the depression [3].

Whilst the plot thickens, we need harder evidence, the sort that can only come from well-conducted randomised controlled trials (or RCTs), and that's a bit of quagmire, as we find a mixture of both positive and negative studies on the role of omega-3 fish oils in depression. But to cut a long story short (for those wanting the whole story, we spell it out in The Health Delusion), when you put all these studies together into a 'meta-analysis', supplements containing the omega-3 fish oil EPA (rather than DHA) appear to be effective in improving symptoms of depression [4]. Whilst most of us would do well to eat more oily fish generally, for those suffering with depression, there is a persuasive, if not yet conclusive, argument for considering a supplement of 1g per day of EPA (but not DHA) as part of a comprehensive treatment approach (but always to be discussed with the doctor first).

Alongside omega-3 fish oils, we could make similar (if less strong) arguments for a potential role of other nutrients in supporting our mood and mental health, such as zinc [5] and folate [6]. We could even extend that to the removal of deleterious dietary factors, such as trans fats, which have recently been implicated in exacerbating our mental health woes (more about that here ).

With burgeoning rates of depression, and our modern day diets in a pretty woeful state, is it time we started integrating nutritional strategies into the prevention and treatment of depression? It's not as if the pharmaceutical solutions are a holy grail, given the significant numbers who either derive little or no benefit from them, or are afflicted by side effects.

Surely this is food for thought?

[1] Hibbeln JR (1998) Fish consumption and major depression Lancet 351(9110):1213

[2] Lin PY et al (2010) A meta-analytic review of polyunsaturated fatty acid compositions in patients with depression Biol Psychiatry 68(2):140-7

[3] Edwards R et al (1998) Omega-3 polyunsaturated fatty acid levels in the diet and in red blood cell membranes of depressed patients. J Affect Disord 48(2-3):149-55

[4] Sublette ME et al (2011) Meta-analysis of the effects of eicosapentaenoic acid (EPA) in clinical trials in depression. J Clin Psychiatry 72(12):1577-84

[5] Cope EC, Levenson CW (2010) Role of zinc in the development and treatment of mood disorders Curr Opin Clin Nutr Metab Care 13(6):685-9

[6] Papakostas GI et al (2012) Folates and s-adenosylmethionine for major depressive disorder. Can J Psychiatry 57(7):406-13

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