Questioning Answers: #Breadgate and nutritional psychiatry

The review paper by Paola Bressan & Peter Kramer [1] (open-access) titled: 'Bread and Other Edible Agents of Mental Disease' has been getting a few people a little hot under the collar recently. With it's own Twitter hashtag #breadgate it looks like the idea that certain foods might have something of a bearing on "human behaviour and mental health" has not been received particularly well. I might add that this not the first time that such ideas have been entertained (see here) but there was no such outcry on previous occasions...

As anyone who drops by this blog might know, I'm quite interested in the idea that what we eat and how it's metabolised might have some important implications for SOME people in terms of not just their physical health but also other facets covering behaviour and cognition. I've also talked about it in the peer-reviewed domain quite a bit too using conditions such as phenylketonuria (PKU) as a template. In their latest paper, Bressan & Kramer discuss the quite long-running idea that [some] cereal grains, the starting material for foods like bread, might have some interesting physiological effects that could have a bearing on mental health and wellbeing.

I should at this point mention that I was invited to peer-review the Bressan / Kramer article. I accepted (given my research in this area) and as well as providing a review also let the editor and authors know that my view whilst as unbiased as possible did come alongside a few conflicts of interest (COIs) such as the book that graces the edge of this blog. The journal editor accepted this fact and my comments alongside those of a far more notable researcher were included in the peer-review process.

The Bressan / Kramer paper presents quite a thorough overview of the research looking at food and psychiatry. The language is quite stark in places as words like 'defect' and 'derangement' are included in the text (something that I queried during peer-review) and with a sub-heading titled 'Diet as a Cure' the authors are pretty forth-right in their interpretation of the available peer-reviewed evidence. I would be perhaps less strong in any claims made but ho-hum. I might add that this is not the first time that this authorship team have talked about big hypotheses...

Without seeming like I am springing to the defence of the Bressan / Kramer paper I have decided to list a few previous blog entries that I've written about other relevant texts in the peer-reviewed domain that add something to the discussions in this area. I'm sure that Bressan / Kramer if they have heard about the 'discussions' around their paper are able to defend their writings and so I'm not doing this to somehow cover their backs. I do however think it is important to talk about this topic and this is as good an opportunity as any...

So:

Brain and gut in autism: a historical perspective
For many years now, diet and [some] autism has been discussed. The work of the late Curt Dohan was the leader in this emerging field and his suggestion that [some] schizophrenia might have a dietary component. Before you ask it, no, no-one has ever said that diets devoid of gluten and casein are some sort of cure-all for all autism... they're not. But that does not mean there might be 'best responders' to this type of intervention (see here) in terms of their effect on some behaviours linked to autism. The mechanism for any effect from diet could also be multi-fold (see here).

Psychotic symptoms managed by a gluten-free diet?
Yes. it's a case report, but there are quite a few of them in the peer-reviewed literature talking about dietary manipulations seemingly affecting often quite severe psychiatric presentation. There are more controlled trials too if you want to have a look...

More gluten sensitivity and schizophrenia
The immune system seems to be in the ascendancy when it comes to psychiatry these days (see here also) and diet has been mentioned as an influencing variable on immune function...

Gluten free diet adherence reduces depression in coeliac disease
Building on the idea that coeliac disease - that archetypal autoimmune condition where gluten is the baddie - might have quite a few more 'presentations' than just the physical, there is some emerging peer-reviewed evidence to suggest that adherence to a gluten-free diet might have multiple benefits for certain groups.

Just what is 'non-coeliac gluten sensitivity'?
The idea that outside of coeliac disease there may be a spectrum of 'gluten-related ills' is not a new one. There are still gaps in the research literature and in particular, whether non-coeliac gluten sensitivity (NCGS) might intersect with certain behavioural and/or psychiatric labels but...

Schizophrenia and milk
With the focus also on milk, or rather the casein protein that is also said to produce peptide metabolites that might not be a millions miles away from various opioid-like compounds like to gluten digestion (hence the name casomorphins), I've included reference to the David Niebuhr et al paper too titled: 'Association between bovine casein antibody and and new onset schizophrenia among US military personnel'. Correlation is not causation but this and other data are interesting.

Intestinal permeability: an emerging scientific area (also with autism in mind)
Gluten 'punching holes in the gut' is mentioned in some of the discussion about the Bressan / Kramer paper and with it the words 'leaky gut' make an appearance. As per my ramblings on some of the peer-reviewed science in this area, there is emerging evidence for this concept in relation to specific conditions including the fantastic paper by Laura de Magistris and colleagues [3] citing food as having a potentially modifying effect.

These are just a selection of the entries that I've written on this blog covering the topic of nutritional psychiatry (see here) but there are more. Accepting that "mental disease" (authors term not mine) covers quite a lot of ground and even within the various labels we have a lot of heterogeneity (see here for example) I would suggest that more research is required into how diet might influence behaviour and psychiatry. The paper by Dash et al [3] similarly titled: 'Diet and common mental disorders; the imperative to translate evidence into action' recently published (in the same family of journals) reiterates that there is more to do in this area including the identification of potential 'best responders' to this type of approach. Diet again, is not put forward as a cure-all for every single label/condition, but that doesn't mean it might not be useful to look at it for some.

I know there is still quite a lot of hostility to the idea that what we eat (or don't eat) might have a bearing on something other than physical health. I'm not advocating for any universal 'change your diet to this' approach to manage mental health issues but I do believe that there is enough peer-reviewed science out there to merit some further sensible discussions on the topic...

Music to close, and what else but Toast... a little bit of toast.

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[1] Bressan P. & Kramer P. Bread and Other Edible Agents of Mental Disease. Front Hum Neurosci. 2016 Mar 29;10:130.

[2] de Magistris L. et al. Alterations of the intestinal barrier in patients with autism spectrum disorders and in their first-degree relatives. J Pediatr Gastroenterol Nutr. 2010 Oct;51(4):418-24.

[3] Dash SR. et al. Diet and common mental disorders; the imperative to translate evidence into action. Front. Public Health | doi: 10.3389/fpubh.2016.00081.

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