Yes, of course there is an important impact. Anyone can observe this in oneself, people around you as well as your patients by using direct observation. You need to think critically so you are not fooled by placebo and other unspecific effects. One common finding is that people consuming lots of sugar may have more fatigue, anxiety and depression. Over the last few years more research papers have been published in scientific journals of high rating. Most of these papers are epidemiological in character. Here are five of these papers:

Sánchez-Villegas A, et al. Association of the Mediterranean dietary pattern with the incidence of depression: the Seguimiento Universidad de Navarra/University of Navarra follow-up (SUN) cohort. Arch Gen Psychiatry 2009;66:1090-8

Akbaraly TN, et al. Dietary pattern and depressive symptoms in middle age. Br J Psychiatry 2009;195:408-13

Jacka FN, et al. Association of Western and traditional diets with depression and anxiety in women. Am J Psychiatry 2010;167:305-11

Jacka FN, et al. A prospective study of diet quality and mental health in adolescents. PLoS One 2011;6:e24805

Quirk SE, et al. The association between diet quality, dietary patterns and depression in adults: a systematic review. BMC Psychiatry 2013;13:175

The challenges are many: There is no food which is optimal for all people. We are biochemically different. This is further related to genetics, polymorfisms, epigenetics, stress, food and supplement intake, different diseases and other environmental factors. Patients need to be studied prospectively with relevant measurements.

Another problem is the lack of knowledge within the scientific community. This means we have to deal with prejudice and denial. Many doctors and researchers are unaware of the research literature in this field which is not at all small.

All the best/Bo

Good topic Geir!...

I consider health & illness in an entire organism: mind, spirit, relations, cognitions, and... diet!

My answer... absolutely yes: food impact on mental health; like the culture, weather, urban/rural situation... but, the effects of food are faster (not usually recognized). Then, there are opportunities dietary; for example the effects on dementia and alcoholism is well known

Challenges?

- Nutrition on mental illness (well-know)

- Effects of contemporary nutrition on mental health & brain (use of flavorings, genetic transformation, preservatives, contaminations. ...)

- Impact of nutrition on mental health treatment (co-work between mental health theraphy and nutrition treatment on depresion, development disorders... anxiety... or schizophrenia...). On dementia there are many publications...

- effects of nutrition on wellness and mental health

- nutrition "medicines" and/or nutrition poison (use of coffe, wine, chocolate, algae...)

The major challenges are how to introduce the nutrition like a part of the formation and expertise of the mental health professionals.

Have a good dinner!!

Yes, of course there is an important impact. Anyone can observe this in oneself, people around you as well as your patients by using direct observation. You need to think critically so you are not fooled by placebo and other unspecific effects. One common finding is that people consuming lots of sugar may have more fatigue, anxiety and depression. Over the last few years more research papers have been published in scientific journals of high rating. Most of these papers are epidemiological in character. Here are five of these papers:

Sánchez-Villegas A, et al. Association of the Mediterranean dietary pattern with the incidence of depression: the Seguimiento Universidad de Navarra/University of Navarra follow-up (SUN) cohort. Arch Gen Psychiatry 2009;66:1090-8

Akbaraly TN, et al. Dietary pattern and depressive symptoms in middle age. Br J Psychiatry 2009;195:408-13

Jacka FN, et al. Association of Western and traditional diets with depression and anxiety in women. Am J Psychiatry 2010;167:305-11

Jacka FN, et al. A prospective study of diet quality and mental health in adolescents. PLoS One 2011;6:e24805

Quirk SE, et al. The association between diet quality, dietary patterns and depression in adults: a systematic review. BMC Psychiatry 2013;13:175

The challenges are many: There is no food which is optimal for all people. We are biochemically different. This is further related to genetics, polymorfisms, epigenetics, stress, food and supplement intake, different diseases and other environmental factors. Patients need to be studied prospectively with relevant measurements.

Another problem is the lack of knowledge within the scientific community. This means we have to deal with prejudice and denial. Many doctors and researchers are unaware of the research literature in this field which is not at all small.

All the best/Bo

Consider looking at the literature on nutrition, dietary supplements, and mental health. Consider looking at papers published in a lesser known journal that has been published for over 40 years - The Journal of Orthomolecular Medicine. During its formative first two decades it focused a great deal on research, studies and clinical case reports related to the role of nutrients on mental health and psychiatry. The journal has a subject and author index that covers the last 40 years of publications. The International Clinical Nutrition Review, now out of print, summarized studies published world wide related to this area of interest, published in Sydney, Australia. It can be found in libraries around the world. There is also the Journal of Applied Nutrition. These are journals often overlooked as they were or are not carried by PubMed. Nevertheless, they have proven to contain very interesting papers either questioning the efficacy or safety of pharmaceutical drugs or demonstrating effective alternatives to them. There are also many books on the subject worth reading. I recall a work by the Berkeley-based psychiatrist, Michael Lesser, MD, who was trained at Cornell University Medical College and the Albert Einstein Medical Center, published by Random House in 1980. In 1977 he testified before the U.S. Senate on the subject of nutrition and mental health. For example, he discussed studies in his book that occurred in France in the 1920's using rubidium salts to treat manic depression with some remarkable outcomes. He observed similar responses to those who had not responded to lithium in his own practice. He published a later work, The Brain Chemistry Diet, that might be of interest. One of many many such works worth reading by numerous authors who have researched the role of nutrition and mental health.

See also my question:

Why isn’t nutrition a bigger part of conventional medical school education

http://tinyurl.com/ovqhxuk

Yes, definitely!

http://www.nutritionj.com/content/pdf/1475-2891-7-2.pdf

http://www.psychosomaticmedicine.org/content/61/5/712.full.pdf+html

Dear Geir, I am not a psycologist but I have some experiences with my own mental states. Whenever fruits are omitted from nutrition I feel depression and sadness. Air pollution and grayish and cold weather have similar effects, while fresh air and blue sky with a temperate sunshine help me feel happy.

See also my question:

Does psychotherapy give changes in the biochemical parameters?

http://tinyurl.com/oymhu9d

Well, of course does our choice of food impact on our mental health, I dare say. Anything else would be rather strange. These are my favourite quotes on the matter over/of mind and food:

“All diseases begin in the gut!” - Hippocrates (460-370 BC)

“The primary seat of insanity generally is in the region of the stomach and intestines.” - Phillipe Pinel (1745–1828)

“I intend to live forever, or die trying” - Groucho Marx (1890-1977)

Current research and writing confirm what has been known for a long time and in different ways from within different paradigms. See for instance:

http://www.drperlmutter.com/about/grain-brain-by-david-perlmutter - which reads:

"Have questions about gluten intolerance, a gluten free diet or the foods that help improve brain health? In Grain Brain, Dr. Perlmutter offers suggestions on how to fuel the brain properly with sound nutrition. These basic changes can help alleviate, or even reverse brain disease, eliminate brain fog symptoms, and improve memory and energy levels".

-and-

http://www.gaps.me/ - which is introduced thus: "Gut and Psychology Syndrome (GAPS™) - Natural treatment for autism, ADHD/ADD, dyslexia, dyspraxia, depression and schizophrenia",

as well as the recent Gluten Summit - http://theglutensummit.com/

or Nora Gedgaudas's "Food for Thought: Eating for Better Brain Function": The 4 "brain factors" you MUST know about to truly improve your brain health and mental performance... // The ONE NUTRIENT that — when missing — is most likely to result in brain shrinkage... /// The three simplest ways to keep your blood sugar stable, so you never crash after meals or in the afternoon... which can be found here http://realfoodcon.com

Food may influence by several ways mental health.

But the question is related to food choice, which is a different issue.

When we discuss about food choice, that should imply that the subject is informed about the dietary constituents chosen and makes an informed decision.

Helas that is a complicated issue.

Even if one woud decide to avoid food containing colorants, conservants, E-s and other chemical additives, he/she hardly can be assured by the labels of the food bought in supermarkets about the standards used during the processing of the dietary products. Probably the only way to avoid chemicals in food would be to go to a farm somewhere up in the remote mountains and farming there. If one choose to live in cities, thet goes together with choosing an unhealthy diet.

Mental helath can be affected by

- prion disease

- mineral and oligoelement deficit - see for ex iodine thyreopathy or selenium, lithium

- essential amino-acid deficiencies

- chronic poisoning (lead, etc)

- psychoactive substances contained in food - like alcohol, mushrooms, coffein, etc

Great information on this forum and I had no idea it was happening (smile). So much of what I would have contributed has already been contributed and most eloquently stated by all of you. Thanks, Geir, for drawing my attention to the discussion--maybe I will find a morsel or two missed in there somewhere and add my two cents.

Food choices most definitely impact mental health and mental development. I personally have worked with children with mental illness and seen their condition improve significantly with changes in diet. What we eat impacts the way our genes behave making us more or less susceptible to dis-ease, including behavior abnormalities. Traditional medical schools do not cover the gene-environment aspects of nutrition and nor do they cover general nutrition. Nutrition education is not even covering gene-environment interactions yet!! Education needs to catch up with the literature and this will take time.

Some nutrients are very important for both physical and mental health, e.g. caffeine. Mori information in attached publication.

Article Chronic caffeine intake affects lysozyme activity and immune...

Here, you are:

http://www.ncbi.nlm.nih.gov/pubmed/24126083

http://www.ncbi.nlm.nih.gov/pubmed/24099097

http://www.ncbi.nlm.nih.gov/pubmed/23658694

http://www.ncbi.nlm.nih.gov/pubmed/23594136

Enjoy!!

Of course, this is extremely important problem, which deserves great attention. However, the today understanding of the physicochemical grounds of the information transmission and of the response impulses which are intrinsic to the living bodies is scarcely sufficient for answering this question. Meanwhile, it is quite possible that the ideas that underlie the MRH-hypothesis (e.g., V.E. Ostrovskii, E.A. Kadyshevich, Mitosis and DNA replication and life origination hydrate hypotheses: common physical and chemical grounds. In: DNA Replication – Current Advances, Seligmann, H., Ed.; InTech: Rijeka, Croatia (2011) 75–114, see ResearchGate), namely, the negative role of the protein depositions in the intracellular protoplasm and at the DNA strands, along with other factors, such as heredity, different abnormal defects, etc., can influence the signal transmissions between different tissues of organisms. If so, the composition and volume of nutrition are, apparently, capable of influencing the mental health. It cannot be excluded that this idea that underlies the MRH-hypothesis could be useful when discussing the question under consideration.

Although it may seem intuitive that diet influences mental state and mental disorders, in fact this is by no means either obvious nor necessary, so I have recently reviewed the evidence to data on this issue, restricting attention to high-level human clinical evidence with sufficient or higher methodological quality scores (MQS), to provide a solid evidentiary foundation to our intuitions when validated.

THE ISSUES

First, as to the question of the relationship between diet and mental health, this decomposes into two subdomains:

(1) the effect of dietary components, such fish oils/omega-3 fatty acids or fruit and vegetables (F V) or folates, and

(2) the effect of dietary patterns, such as the Mediterranean or the Western or the Prudent dietary pattern

on mental health, and here mental health generally is either clinical depression, or cognitive impairment (such including minimal cognitive impairment (MCI), or Alzheimer's/Dementia).

In addition, we have two broad categories of evidence to weigh on the question:

(1) RCT (randomized controlled trial) data, OR systematic reviews or meta-analyses of RCT studies) data.

(2) non-RCT clinical data (such as non-RCT epidemiological; prospective cohort; retrospective analysis; or cross-sectional studies), with all their inherent methodological limitations (such as prevalence-incidence bias in cross-sectional studies, etc.) , OR meta-analyses of non-RCT clinical studies. And given the methodological limitations of non-RCT studies, to confirm the findings obtained in these initial cohort studies, we need further observational longitudinal studies with improved methodology, as well as large randomized primary prevention trials, with interventions based on changes in the overall food pattern, that include participants at high risk of mental disorders.

So I will first examine the evidence concerning specific components of the diet and their association, or lack thereof, with mental health, then turn to the issue of dietary patterns. And to help motivate further research, I note that I recently encountered the opinion that we must stop wasting time on studying, and researching, and teaching nutrition!!! This overlooks the critical centrality of diet and nutrition in virtually all human chronic and oncologic disorders, as demonstrated in hundreds and hundreds of robust, critically appraised, systematically reviewed and meta-analyzed human clinical studies. In addition, it fails to engage the growing breakthrough data supporting the critical role of food as an epigenetic modulator (especially via epigenetic alteration through DNA methylation), given that diet can affect transgenerational gene expression via heritable epigenetic mechanisms, in cancer, chronic inflammatory and metabolic disorders, one of the most exciting frontier edges of unifying and integrating medical research. The review below is just a small part of my own contribution to the arena of what may be called "food and mood", although it includes influences on stroke as well as cognitive impairment, not just depression, and itself in part of a larger whole of the nutrigenomics of human health and disease.

DIETARY COMPONENTS

---> Non-RCT Data

Diet may potentially influence the risk of depression, and although the evidence is not yet conclusive, it has seemed plausible, if not probable, to conclude that a diet including omega-3 fatty acids, olive oil, fish, fruits, vegetables, nuts, and folate may have a protective effect against depression, while there is some evidence indicating that diets containing processed foods, such as chocolate, refined grains, processed meat, whole-fat dairy products and fried foods, are associated with a higher risk of depression. However, most studies using a cohort subgroup run the strong possibility of selection bias, and review - whether systematic reviews or meta-analyses - run the risk of publication bias, while narrative analyses (non-meta-analytic) are far more prone to subjectivities.

What we critically need are robust prospective cohort studies, preferably if available RCTs, designed specifically to study the association between diet and depression risk. As an example, a recent systematic review and meta-analysis of only longitudinal cohort studies [1] found that even with such studies, diet - in the form of nutrients such as folate, omega-3 fatty acids and monounsaturated fatty acids; foods such as olive oil and fish; and a diet rich in fruits, vegetables, nuts and legumes; and on the other hand, a high consumption of processed food and sugary products may increase the likelihood of depression - may potentially influence the risk of depression, but the evidence was nonetheless judged not yet conclusive, given the lack of strong or compelling consistency in the findings (and note only one includable study was randomized).

On the positive side, a prospective analysis of the First National Health and Nutrition Examination Survey Follow-up Study [2] found that low fish consumption was a risk factor for SDM (severely depressed mood) among men, and a Finnish cross-sectional study [3] found that that high fish consumption protected against depression only for men but not for the women, but there were no clear associations between omega-3 PUFAs and the occurrence of depressive episodes.

Also, most recently, NIH researchers conducted a cross-sectional study [4] which found that higher intakes of n–3 fatty acids, and relative to n–6 fatty acids (ratio: n–3:n–6) were associated with lower risk of elevated depressive symptoms, specifically in domains of somatic complaints (mainly n–3 PUFAs) and positive affect (mainly n–3 HUFAs (highly unsaturated fatty acids)). This is in part confirmed by the results of the SU.VI.MAX 2 Study [5] which found no longitudinal association between n-3 PUFA intake and incidence of depressive symptoms, but did observe an association in cross-sectional analyses, possibly therefore reflecting unhealthy dietary patterns among subjects with depressive symptoms. In addition, given that lower concentrations of n−3 PUFAs have been reported to be associated with cognitive impairment and dementia, and with depression (a potential risk factor for cognitive decline), another cross-sectional study [6] from Taiwan investigated associations between n−3 PUFA concentrations in erythrocyte membrane or plasma, and cognitive function, in an at-risk population of older subjects with prior major depression, finding that total erythrocyte n−3 PUFA concentrations are positively associated with cognitive function (immediate recall in particular), and that lower concentrations of n−3 PUFAs or ALA (α-linolenic acid ) in erythrocyte membranes may be good predictors for cognitive impairment in older people with previous recurrent depression.

We also have the SUN Project prospective cohort study [7] in Spain which found a detrimental relationship between TFA (trans unsaturated fatty acids) intake and depression risk, whereas weak but significant inverse associations were found for MUFA (monounsaturated fatty acids), PUFA (polyunsaturated fatty acids) and olive oil.

But we also have non-RCT data that are equivocal or negative: a systematic review [8] of 19 studies (four double-blind rRCTs, four cohorts, two cross-sectional lines and nine case-controls) found that 13 showed a significant positive association between omega-3 and depression, while six studies did not show a relationship between the referred variables, leaving the issue open; similarly, the cross-sectional analysis of fish consumption and late-life depression in seven low- and middle-income countries [9] failed to support a significant association, and others studies were also equivocal [10], as well as the Harvard longitudinal prospective analysis [21] of the Nurses' Health Study (NHS) which found no protective effect of long-chain n−3 from fish on depression risk, although there was support for the hypothesis that higher ALA (α-linolenic acid) and lower LA (linoleic acid ) intakes reduce depression risk, suggesting further study. And while some promising findings exist with regards to fruit and vegetable intake and psychological well-being, overall, results are inconsistent, requiring well-designed randomized controlled trials (see below) to investigate the relationship further as oft noted [11].

---> RCT Data

So given the inconsistent findings cited above, we need to turn to RCT data, and if available and with robust methodology, the RCT data would trump the non-RCT from epidemiological, prospective cohort, retrospective analysis, or cross-sectional studies, and provide a Level I determination (unless there are irresolvable inconsistencies even across RCT studies).

Let's first look at the issue of omega-3 fatty acids (FAs) or, technically omega-3 PUFAs. Here we have no consensus: although there is some evidence to suggest that n-3 PUFA intake is associated with reduced depressive symptomology, particularly in females, it was found that these results were generally limited to epidemiological studies, while on the other hand, results from randomized controlled trials (RCTs) are mixed and hence inconclusive [12].

Part of what may be going on here is that there may be a dose dependency, and a component-specificity: low-dose omega-3 PUFAs had some efficacy in the treatment of mild to moderate depression in elderly participants of a double-blind, placebo-controlled RCT [13]. In another recent RCT [14], it was found that the omega-3 FA component EPA had greater efficacy compared to DHA or placebo as an adjunctive treatment in mild-to-moderate depression, confirming previous findings [15] that EPA - not DHA - was the omega-3 component responsible for benefit in depression.

Conclusions on Omega-3 Fatty Acids from RCT Data

It would appear from some RCT data [13,14,15] that that low-dose omega-3 FAs, especially if EPA-rich (but not DHA) show efficacy as adjuncts in mild to moderate depression, but there is contradictory data from other RCT data: in a meta-analysis [16] of 13 randomized, placebo-controlled trials (RCTs) examining the efficacy of omega-3 fatty acids (FAs), no significant benefit of omega-3 FA treatment was found compared with placebo, and the authors concluded, correctly according to my own analysis of the underlying data, that nearly all of the treatment efficacy observed in the published literature may be attributable to publication bias (note however, that the RCTs were restricted to the specific issue of omega-3 FAs, and hence did not address the broader issue of dietary patterns, as did the PREDIMED RCT (45), discussed more fully below, which found a clear inverse (positive) association with depression deriving from the Mediterranean dietary pattern). And the lack of association between n-3, n-6, n-3 from fish and depression risk, or between the ratio n-3:n-6 and depression risk has also been documented in recent literature [16] which can be seen to downplay the importance of these fat subtypes or their ratio on depression [17,18,29,30].

Thus, our review must conclude that the divergent/inconsistent results of both non-RCT and RCT data fail to clearly support a clear inverse association between omega-3 FA consumption and depression, although there is provisional data strongly suggestive, but not decisive, of the likelihood that the EPA component [13,14], but not the DHA component nor overall omega-3 consumption, may provide a positive benefit in the treatment of mild to moderate depression

Conclusions on Folate from RCT Data

As to folate/folic acid, there is some evidence suggesting that folate supplementation may be an effective co-adjuvant in the pharmacological treatment of (unipolar) depression [19], this was a review of largely non-RCT data. However, a recent randomized control trial (RCT) failed to find a positive effect of folate in the prevention of depressive symptoms [20]. That leaves RCT data weighing against a clinical relevant association between folate levels and depression or depression risk, and we must await further more robust mature RCT data to be decisive on the issue.

Conclusions on Olive Oil from RCT Data

We have considerable data [32,33], including strong RCT data [35] supporting that the bioactive polyphenols of olive oil (as found in the Mediterranean Pattern) exert important anti-inflammatory properties that can improve endothelial function, observing also that the antioxidant actions of extra virgin olive oil (EVOO) components, in particular tyrosol, are capable of restoring the intracellular antioxidant defenses [34] decreased among depressive patients.

DIETARY PATTERNS

---> Non-RCT Data

An independent prospective analysis [22] of the same NHS database cited above found no significant association between the dietary patterns - the Prudent (high in vegetables) and Western (high in meats) diet patterns were tested - and depression risk in middle aged or older women. However, that was for the two dietary patterns of Prudent and Western, but another prospective study [23] of this same NHS database (by the same team) investigating the inflammatory dietary pattern - a diet, that is, which includes more foods that trigger inflammation—like sugar-sweetened or diet soft drinks, refined grains, red meat, and margarine—and fewer foods that restrain inflammation—like wine, coffee, olive oil, and green leafy and yellow vegetables, leading to higher plasma levels of inflammatory markers (C-reactive protein, interleukin-6, tumor necrosis factor α receptor 2) - found that the inflammatory dietary pattern is in fact associated with a higher depression risk of between 29 to 41% greater risk of being diagnosed with depression than those eating mostly the less inflammatory diet, suggesting again that chronic inflammation may underlie the association between diet and depression.

And the results of Whitehall II prospective cohort study [24,25] showed that the Whole Food pattern (rich in vegetables, fruits, and fish) was inversely associated with depression, while the Processed Food pattern (rich in sweetened desserts, fried food, processed meat, refined grains, and high-fat dairy products) showed a direct association with depression in a middle-aged population, in which the prevalence of diabetes was significantly higher (by two-fold) among depressed persons compared with nondepressed ones (5% versus 2.5%). Furthermore, in the GAZEL cohort study [27], after 1-year follow up it was found that men who were in the highest quartile of low-fat, western, high snack, and high fat-sweet diets and women in the highest quartile of low-fat and high snack were more likely to be depressed versus the lowest quartile, while conversely, the highest quartile of healthy and traditional dietary patterns were associated with lower odds ratio for depression among women compared with the lowest quartile (the traditional diet was rich in fish and fruit consumption and healthy diet was rich in vegetables consumption).

Furthermore, another finding from the SUN cohort study [28] demonstrated an inverse relationship between the adherence to Mediterranean diet (rich in legumes, fruits, vegetables, fish and cereals, but low in meat and dairy products) and depression, while consumption of fast foods and commercial baked goods increased the risk of depression (among Spanish subjects) [31]. And in another meta-analysis [37], 22 eligible studies were included (11 on stroke, 9 on depression, and 8 on cognitive impairment, with one on Parkinson's disease), and it was found that high adherence to Mediterranean diet was consistently associated with reduced risk for stroke (RR = 0.71), depression (RR = 0.68), and cognitive impairment (RR = 0.60). When adherence was moderate, there were also similar associations with reduced risk for depression and cognitive impairment, but with moderate adherence, the protective trend concerning stroke was only marginal, suggesting that the optimal consumption level is high adherence to the Mediterranean diet to jointly protect against depression, cognitive impairment and stroke. And in subgroup analyses, the protective actions of high adherence were seen in reduced risk for ischemic stroke, mild cognitive impairment, dementia, and particularly Alzheimer disease (the protective effects of high adherence were independent of age, but those of moderate adherence were dramatically faded with more advanced age). Thus, adherence to a Mediterranean diet pattern appears to contribute to the prevention of a spectrum of brain diseases, including mood (depression), neurological (Alzheimer's and dementia) and cardiovascular (stroke), the alter suggesting that cardiovascular disease and depression may share some common nutritional determinants related to subtypes of fat intake [38,39].

And in two of the reviewed studies [1], consistent associations between dietary patterns and the risk of depression were found., especially again for the Mediterranean pattern, which has been associated with significant reductions in overall mortality, mortality for cardiovascular diseases and cancer mortality, and with a lower incidence of cancer, Parkinson's disease and Alzheimer's disease [40], and was also found to be associated with a lower risk of depression [28]. Thus, greater depression severity was associated with poorer overall diet quality in linear regression models controlling for income, education, depression-related appetite change, binge eating disorder, and other potential confounds, where these associations with diet quality were primarily driven by greater intake of sugar, and sodium, and more severe depression was associated with poorer overall diet quality among treatment-seeking women with major depressive disorder (MDD )"and obesity [41]. And many other studies showed that diet quality is a protective factor against depression [42,43,44,46].

We still have some inconsistent findings, but these are countervailed by the positive data. So another study among Japanese [26] did not show any significant association between depression and various dietary patterns (including the Healthy, the Western, the Bread and Confectionery, and the Alcohol and Accompanying dietary patterns), but note that the Mediterranean pattern was note explicitly tested (in this same study, various dietary determinants of depression - energy intake, the B vitamins B2, B6, and B12, and n-3 PUFA - were found not to significantly differ between depressed and nondepressed subjects). However, a systematic review [36] evaluated existing evidence regarding the association between diet quality and depression, with 25 studies from nine countries meeting eligibility criteria. In a best-evidence analyses it was found that there was limited - but non-trivial - evidence to support an association between traditional diets (Mediterranean) and depression, the authors concluding that although a true causal association between diet quality and depression may exist, but is being masked by methodological shortcomings.

Conclusions on Dietary Patterns from Non-RCT Data

Despite some inconsistent findings [22,26,36], the balance of the aggregate non-RCT data nonetheless suggests a strong probability of a protective effect from, most especially, the Mediterranean pattern (as likely also from the Whole Food pattern, and from non-inflammatory diet patterns). With the Mediterranean dietary pattern, the benefits were protection against a spectrum of brain diseases, including depression, Alzheimer's, dementia and cognitive impairment), as well as stroke.

DIETARY PATTERNS

---> RCT Data

The PREDIMED trial [45], a multicenter randomized primary prevention field trial of cardiovascular disease in elderly men and women at high risk of cardiovascular disease (over half with type 2 diabetes) found a statistically significant inverse association with depression for participants assigned to a Mediterranean diet supplemented with nuts compared with participants assigned to the control group when the analysis was restricted to participants with diabetes. The result suggest that a Mediterranean diet supplemented with nuts could exert a beneficial effect on the risk of depression in diabetic patients.

CONCLUSIONS AND EXPLANATIONS: THE QUESTION OF WHY "FOOD AND MOOD"

Nutritional variables appear to play an etiological role in unipolar depression, such that certain nutrients and/or foods constitute risk factors, suggesting that dietary modifications may be assistive in the prevention, and possibly also the therapeutics, of unipolar depressive disorders, especially dietary patterns that proximate the olive oil-rich and EPA-enriched Mediterranean dietary pattern.

We can now on the basis of both preclinical data and human clinical evidence posit a plausible rationale for these associations, which begins with the recognition that among depressive patients low-grade inflammatory status is commonly observed [47,48] and that pro-inflammatory cytokines may interfere with neurotransmitter metabolism, reduce plasma tryptophan level, impair neurotransmitter metabolism by inhibition of the gene expression of BDNF (Brain-Derived-Neurotrophic-Factor) expression [49,52], BDNF being a peptide critical for axonal and neuronal growth and survival and synaptic plasticity and function. Furthermore, not only have low BDNF levels have been reported in patients with depression, but antidepressants appears to up-regulate BDNF (as well as other neurotrophic and growth factors) [50], and diet-influenced endothelial-produced BDNF - especially via anti-inflammatory dietary components and patterns - appears to partially mediate neuroprotection by modulating serum levels of inflammatory markers. [51]. And we finally have the first of direct human clinical data in essential agreement of this hypothesis: in the PREDIMED-NAVARRA randomized trial, participants assigned to Mediterranean diet enriched with nuts showed a significant lower risk of low plasma BDNF values as compared to the control group, while among participants with prevalent depression at baseline, significantly higher BDNF levels were found, showing that adherence to the Mediterranean dietary pattern was associated to an improvement in plasma BDNF concentrations in individuals with depression.

METHODOLOGY OF THIS REVIEW

A search of the PUBMED, Cochrane Library / Cochrane Register of Controlled Trials, MEDLINE, EMBASE, AMED (Allied and Complimentary Medicine Database), CINAHL (Cumulative Index to Nursing and Allied Health Literature), PsycINFO, ISI Web of Science (WoS), BIOSIS, LILACS (Latin American and Caribbean Health Sciences Literature), ASSIA (Applied Social Sciences Index and Abstracts), SCEH (NHS Evidence Specialist Collection for Ethnicity and Health) and SCIRUS databases was conducted without language or date restrictions, and updated again current as of date of publication, with systematic reviews and meta-analyses extracted separately. Search was expanded in parallel to include just-in-time (JIT) medical feed sources as returned from Terkko (provided by the National Library of Health Sciences - Terkko at the University of Helsinki). A further "broad-spectrum" science search using SCIRUS (410+ million entry database) was then deployed for resources not otherwise included. Unpublished studies were located via contextual search, and relevant dissertations were located via NTLTD (Networked Digital Library of Theses and Dissertations) and OpenThesis. Sources in languages foreign to this reviewer were translated by language translation software.

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Nutrition and digestion cannot be separated: we are not what we eat, but: we are what we are when we have processed what we eat. It is a circular system - with feedback and feedforwards (negative and positive loops) - where food/nutrition conditions the gut flora, which in turn determines what can be absorbed in the future and so on.

Focusing on one substance, like Vitamin C or some specific fatty acid, is quite similar to conducting astronomical experiments on the basis that the universe revolves around the earth. It misses the wider systemic aspects that easily can be observed. If the gut flora reaches a certain state of being - as a result of the bad bacteria (optimally about 15%) gaining too much territory against the good bacteria (approx. 85%) - and the gut wall becomes permeable and toxins that should have been in the toilet end up in the bloodstream, then all manners of problems begin (known as AI, mental and what not diseases usually considered "unexplainable" in the mainstream, pill oriented socalled medicine.)

A leaking gut is a wormhole into a sick dimension and returning to the original state of being - a state defined by bateriological warfare within the healthy gut - can be quite a task and it is a journey that few manage. Most people are pushed further into the dimension of sickness by ignorant doctors and drug pushers, who crudely prescribe toxic shit for a problem of toxin overflow, making matters worse, treating superficial symptoms and leaving causes and origins of problems entirely in the dark.

Good points, all, Martin, and a bitter pill for some to swallow, I'm sure. I would rephrase the "we are what we eat" (an oversimplification) to "we are what we eat and how we synthesize it in the digestive process" (more to the real world results). With so little live bacteria of the good kind left in the modern bodies and an ubiquitous propensity toward perpetual acidosis, we have a great need to get back to organic and bioavailable nutrition. We have fallen deeply into the pit of what consitutes a nutrient, vitamin C, for instance, and I recall in a discussion some years ago an acquaintance that worked with Linus Pauling telling me that he regretted not redefining vitamin C as ascorbic acid in its bioavailable forms (primarily ascorbate with a universe around it consistening of uncountable micronutrients and co-factors). Vitamin D (whatever that is in today's professional parlance), the B-vitamins, A-vitamin, E-vitamins are so far off in official understanding today that it is any wonder we are all talking about the same nutrients. The body's digestion--or, rather, food-to-nutrient synthesis--is key to it all, and the body's intelligence is immensely smarter than our diagrams describing it. I am attaching one of my lecture monographs that attempts to explain the steps. At first blush, those of us of the mechanisitic closed-systems mindset might see these discrete steps as separate and unrelated, when those of us the holisitic open-systems school of thought see it all as one, and our feeble attempts to describe it to our students is woefully inadequate compared to the enormously rich and complex orchestration presented by the human body itself. A pill with a stripped down nutrient, in the latter school of thought, is a toxin, and the food itself becomes the vitamin pill. If only we could bring unified perspectives into such equisite behavioral modeling.

To describe hypercomplex phenomena like digestion and nutrition the aforementioned simple schemata/diagrams may seem an oversimplication indeed. But regarded as a didactical tool, such a diagram represents the first step in understanding the interactions between the different compartments of human body during digestion: eating starts in the nervous system, digestion involves the oro-esophag-gastric and intestinal system with its adnexes (liver, pancreas, gut's bacterial flora) and nutrition is a process unfolding in every living cell. All these processes are intricated on multiple levels, so the human mind needs some help to make the first steps in discovering these intricacies. As every journey starts with a step forward, I believe Max's Flowchart represents the correct direction in understanding digestion.

Nice chart Max...

Having recently done a short nutrition course I learnt why we crave foods that are bad for us. Its to do with the immune system encircling and clumping the proteins that have crossed the leaky gut (due to damaged villi tips). These proteins are in the blood stream where they dont belong and are viewed by the body as aliens (such as gluten). When we don't eat these foods for a couple of days the clumps start to break up and scatter making it harder for the immune system to clump and control therefore we crave them. It is sensible to put four or more days between foods you know are not tolerated well by your body if you cant avoid them all together.

The other area that is interesting is the copper/zinc balance in relation to mental health. Copper toxicity is rising due to its addition to the food supply in the form of plant sprays. It then causes zinc to be less absorb-able and zinc is implicated in about 70 different processes. Organic is becoming more widespread and growing your own is not so hard. We dictate the market with our spending so support the farmers who's food you are happy to eat. A daily drop or two of iodine is essential to counter sprays and radiation regardless and selenium if your local soils are depleted.

About zinc and copper will you find updated information in my article "The role of zinc and copper in autism spectrum disorders" (Acta Neurobiol Exp (Wars) 2013;73:225-36): https://www.researchgate.net/publication/244479056_The_role_of_zinc_and_copper_in_autism_spectrum_disorders

Article The role of zinc and copper in autism spectrum disorders

Heather, that is an interesting theory on the immunological control of the lower gut, and I don't doubt its veracity. Many of the newer models of digestion are based on the static notion of the current cellular pH, hydration, etc.of the population. I mention this, because the gluten factor as well as a host of other more recently discovered food sensitivities do not appear to be problematic to the people, say, 200 years ago when the average diet did not include processed foods, high sugar, high caffeine, and chemicals with which to contend. Allergies, cancer, cardiovascular disease, diabetes, etc., as we know them today, are essentially modern diseases--rare in earlier times. The ocean's and earth's environmental pH and oxygen levels were much higher, also.

In pre-modern times we had other challenges, mostly in terms of lack of variety in food (restricted to geographical, seasonal, storage limitations) that brought pandemics or epidemics that varied to each area. Exposure and use of heavy metals like lead and mercury particularly troublesome in the cities, were almost non-existent in the rural areas, where the majority of the people lived. So, if we took the best examples of populations that had access to variety, few restrictions of necessary nutrients, practically no heavy metal exposure, we find longevity, robust health, and well maintained health throughout their lifetime.

A side-note is that most figures showing historical lifespans are severely tortured because of inclusion of infant mortality rates, natural disasters, and wars. When those rates are removed we find that modern man is not exceptional in his/her ability to live longer. We tend today to credit modern medicince and the food supply with longevity, when under the objective lens, the trends of both are now on a downward trajectory, including problematic lifestyle trends (increased substance addictions, sedentary lifestyle, increased heavy metals--is anyone watching the increased mercury exposure rates in breakage of the new lightbulbs the politicians have foisted upon us?).

So now, we try to explain digestive processes by the more acidic modern gut model and suddenly we are allergic to everything under the sun. Avoid those, comes the reasoning, and we are OK again--when in truth we need to change the foods we eat, allow the naturall chelates back into the food, etc. to take us back to the healthier, more organic state.

I agree it seems easy enough with the knowledge and determination to start eating more organically, and possibly by minute increments the trends are improving. Meanwhile the larger society rages on, spending $3.5 trillion (and counting) dollars in a $15.5 trillion dollar economy on healthcare trying to clean up the mess created from prevailing eating and lifestyle habits. Getting the larger society to where they need to be is going to be our biggest challenge, and so much stands in the way that it is going to rewuire an awareness campaign and the dissemination of knowledge far and wide before the people become nobody's fool and start walking away en masse from the modern offerings that have brought so much suffering.

Terroir can be part of the novelty with certain food choices. Terroir is about the land and the unique taste imparted to its produce.This is attributable to a complex mix of ecological factors, and the presence of certain traces minerals in the soil, that simultaneously impart a unique nutritional value to the food. For instance, water in the brewing and fermentation process may have a significant impact on flavour. Even the utensils used to cook, serve and eat food can affect its taste. By implication, there will also be consequences to a population's neurological/mental health. Harmless food types can sometimes become a bad choice if we are unaware of its source, the food culture and the complex logistics and processing it goes through before it ends up in our mouths. 

http://www.theguardian.com/environment/world-on-a-plate/2015/mar/23/japan-refuses-norways-toxic-whale-meat

We have heard of  chicken soup for colds, "chicken soup for the soul". Here is another one...chicken soup as brain tonic.

http://figur8.net/wedding/2014/03/27/chinese-soups-the-brain-soup/

A fine example is if we can categorize wine and beer as food (liquid form).  They can definitely cloud our judgement (hence our brains) even with small sip of it. It is an epidemic in global scale especially among students in universities.