The key points of this blog post can be downloaded & printed out as a helpful 6-slide-miniatures-to-a-page Powerpoint handout.

Back in December 2009 I wrote a blog post entitled "New research shows diet's importance for preventing depression" where I commented "You know how it is - no buses in sight, then two come along at once. It's been a bit similar for good research on diet and depression. There have been plenty of studies on individual components of diet and mood (e.g. fish, folate, other B vitamins), but very little on the possible psychological effects of diet as a whole."  I then noted that in October of 2009, Sanchez-Villegas & colleagues had published "Association of the Mediterranean Dietary Pattern With the Incidence of Depression: The Seguimiento Universidad de Navarra/University of Navarra Follow-up (SUN) Cohort."   As you can see from the slide below, they showed startling reductions in the risk of developing depression for people who eat healthily compared with those who don't ... and as a bonus, there are great mortality risk improvements as well.

And a month later a similarly eye-catching study was published in the British Journal of Psychiatry - "Dietary pattern and depressive symptoms in middle age" - with results again highlighting the depression-preventing benefits of keeping to a healthy diet, despite adjustment for multiple potential confounding factors including gender, age, marital status, level of education, physical activity, smoking habits, presence of a variety of diseases, & use of antidepressive drugs:

Fascinatingly the Akbaraly paper (see diagrams above & below) suggests that the depression-inducing effects of a bad diet may be even more toxic than the depression-preventing effects of a good diet:  

And a recent paper from Spain - "Dietary fat intake and the risk of depression: the SUN Project" - also touches on the area, highlighting the apparently particularly depression-inducing effects of poor diets (for example, those high in trans fats seem especially bad both for our hearts and our moods - worth scanning food labels & avoiding anything that contains apparently innocuous "partially hydrogenated vegetable oil" and "vegetable shortening").

Marlene Freeman went on to write in "Nutrition and psychiatry", a 2010 American Journal of Psychiatry editorial, "It would be a pivotal change for psychiatry if specific dietary patterns are definitively demonstrated to prevent or diminish psychiatric disorders in prevalence or severity."  And in the two years since, the research has continued to underline this diet-mental state link.  This has been shown for the general population - see for example "Fast-food and commercial baked goods consumption and the risk of depression", "The association between habitual diet quality and the common mental disorders in community-dwelling adults" and "Association of Western and traditional diets with depression and anxiety in women".  Fascinatingly there seems relevance too for post-partum depression - see "Perinatal depression: prevalence, risks, and the nutrition link--a review of the literature" and "Dietary patterns during pregnancy and the risk of postpartum depression".  The use of antidepressants in pregnancy is of debatable overall benefit, so the possibility of improvement from dietary intervention is particularly interesting.  There are similar findings emerging as well for adolescents - "Associations between diet quality and depressed mood in adolescents: results from the Australian Healthy Neighbourhoods Study" and "A prospective study of diet quality and mental health in adolescents".  This latter prospective study is viewable in free full text and is especially important because it found that improving diet quality led to improvement in psychological state.  The authors wrote "In this study, diet quality was associated with adolescent mental health both cross-sectionally and prospectively. Moreover, improvements in diet quality were mirrored by improvements in mental health, while reductions in diet quality were associated with declining psychological functioning over the follow up period. Finally, the reverse causality hypothesis, that the reported associations reflect poorer eating habits as a consequence of mental health problems, was not supported by the available data."  

This is really important information for us to be paying attention to.  It is highly relevant to all of us for our own psychological & physical health.  It's highly relevant to those of us who are parents.  Depression & anxiety rates in kids & adolescents are heart-breakingly high.  Here's something we can do about it.  And it's highly relevant to those of us who are mental health professionals.  We should be routinely asking about diet quality when we see people suffering with psychological difficulties.

The key points of this blog post can be downloaded & printed out as a helpful 6-slide-miniatures-to-a-page Powerpoint handout.

And see the next post "So what dietary advice should we be following - for psychological as well as physical health?"