Dietary fibre deficiency and gut barrier integrity

"Dietary fiber deprivation, together with a fiber-deprived, mucus-eroding microbiota, promotes greater epithelial access and lethal colitis by the mucosal pathogen, Citrobacter rodentium."

So said the findings reported by Mahesh Desai and colleagues [1] meriting an editorial in the publishing journal [2] as the sentiments of 'eating your greens' applies to some rather interesting [mouse] findings.

Fibre (UK spelling) comes in various different forms typically categorised as soluble and insoluble depending on their relationship with water. Using a "gnotobiotic mouse model" - where mice were "colonized with a synthetic human gut microbiota composed of fully sequenced commensal bacteria" - Desai et al reported on the effects of different diets with different fibre content. Their results make for important reading as a fibre-deprived gut was associated with the rise of some rather potent bacteria that seemed to enjoy dining out on the "colonic mucus barrier, which serves as a primary defense against enteric pathogens." Yes, mice gut barriers - or some of their components at least - were being eaten by the very bacteria they contain. Enjoy your lunch.

I'm not dwelling too much on the Desai findings, bearing in mind their focus on mice not humans, but I do want to raise a couple of potentially relevant points. First is the focus on the intestinal barrier and how that so-called 'leaky gut' seems to show a connection to dietary fibre intake. Yet more research bringing this woo-like term in from the scientific cold (see here). Next is the idea that if the Desai results are transferable from mouse to humans, they could be relevant to quite a lot of people who perhaps don't enjoy as much dietary fibre as they should. Further, there may be particular groups of people who might be particularly prone to a poor diet [3] (see here too) where the already discussed term 'leaky gut' is also relevant (see here); also bringing in the idea of a role for those trillions of wee beasties (the gut microbiota) that call us home.

I'll be watching for how this research area pans out...

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[1] Desai MS. et al. A Dietary Fiber-Deprived Gut Microbiota Degrades the Colonic Mucus Barrier and Enhances Pathogen Susceptibility. Cell. 2016 Nov 17;167(5):1339-1353.e21.

[2] Gazzaniga FS. & Kasper DL. Veggies and Intact Grains a Day Keep the Pathogens Away. Cell. 2016 Nov 17;167(5):1161-1162.

[3] Bandini LG. et al. Changes in Food Selectivity in Children with Autism Spectrum Disorder. J Autism Dev Disord. 2016 Nov 19.

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Desai MS, Seekatz AM, Koropatkin NM, Kamada N, Hickey CA, Wolter M, Pudlo NA, Kitamoto S, Terrapon N, Muller A, Young VB, Henrissat B, Wilmes P, Stappenbeck TS, Núñez G, & Martens EC (2016). A Dietary Fiber-Deprived Gut Microbiota Degrades the Colonic Mucus Barrier and Enhances Pathogen Susceptibility. Cell, 167 (5), 1339-2147483647 PMID: 27863247

Is a GFCF diet for autism inherently unhealthy? (part 2)

Consider today's entry as a sort of continuation of a previous post looking at the 'horror' that is a gluten-free, casein-free (GFCF) diet for autism (see here).

This time around I'm bringing the paper by Salvador Marí-Bauset and colleagues [1] to your attention and the idea that things might not necessarily be all bad when it comes to the use of a GFCF diet in terms of nutritional quality nor anthropometric values. Indeed, subject to the correct dietetic input, that there may be some important food exchanges going on when a diet devoid of gluten and casein is instigated specifically where an autism diagnosis is mentioned.

I realise that not everyone is as enthusiastic about how food might impact on behaviour and development with at least some autism in mind as I am, but science is coming around to the idea that what we eat (or not) might have some important influences on our being (see here). Appreciating that the GFCF diet is also probably not for everyone [2] (see here also), there continues to be some 'appetite' for such an approach for at least some autism [3]. It is therefore important to understand a little more about what might be the positives and negatives to following such a restrictive dietary regime.

Marí-Bauset et al report results for some 20 children with autism following a GFCF diet compared with 85 "on a regular diet in Valencia (Spain)." This follows a scheme of work from this authorship group looking at various aspects of nutrition when applied to autism [4]. Upon analysing 3-day food diaries, researchers concluded that: "Those on the GFCF diet had a lower weight, body mass index, and total energy, pantothenic acid, calcium, phosphorus and sodium intake." Further however, the GFCF group had: "a higher intake of fiber, legumes, and vegetables" and something of a more favourable fat intake profile that non-GFCF dieters. That last point also ties into other work from the authors [5].

As per the part 1 entry on the nutritional and health related aspects to a GFCF diet for autism (here it is again) there are some details in the Marí-Bauset data that perhaps require some clinical input. I'm thinking specifically about the lower calcium intake in this case, bearing in mind calcium and autism is a very complicated issue (see here) and some continued questioning about the more general link between calcium intake and bone health. The idea that those following a GFCF diet might also present with a lower weight and body mass index (BMI) is also interesting; particularly in light of quite a lot of the chatter in this area focusing on elevated weight and the health effects that can have with autism in mind (see here). I might add that I am in no way endorsing a GFCF diet (or any other diet) for weight loss or management; that's not my job.

The slightly more positive idea that those following a GFCF diet might have a better intake of vegetables and legumes probably also tied into a higher intake of fibre is important. I've previously talked about where the extremes of a limited diet can lead when it comes to [some] autism (see here). Although supplementation has its place in terms of as and when specific deficiencies are present and identified (see here) I think most people would agree that consumption of foodstuffs like fruit and vegetables probably do a better job of supplying nutritional needs than a pill (most of the time). In that respect, one might assume that those on a GFCF diet with more favourable vegetable consumption profile, might be slightly less prone to certain deficiencies. As per other research in this area, we would need a little more biological testing to be sure (see here). The specific idea that fibre intake was higher for the GFCF group is also an important point if one considers fibre to be an essential component when it comes to gastrointestinal (GI) motility, again, as has been specifically mentioned with autism in mind (see here).

In short, and with more research required, the horror that is a GFCF diet for autism might actually with the right clinical input, not be so horrible...

Music: Lily Allen - The Fear.

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[1] Marí-Bauset S. et al. Nutritional Impact of a Gluten-Free Casein-Free Diet in Children with Autism Spectrum Disorder. J Autism Dev Disord. 2015 Oct 1.

[2] Buie T. The relationship of autism and gluten. Clin Ther. 2013 May;35(5):578-83.

[3] Whiteley P. Nutritional management of (some) autism: a case for gluten- and casein-free diets? Proc Nutr Soc. 2015 Aug;74(3):202-7.

[4] Marí-Bauset S. et al. Nutritional status of children with autism spectrum disorders (ASDs): a case-control study. J Autism Dev Disord. 2015 Jan;45(1):203-12.

[5] Marí-Bauset S. et al. Fat intake in children with autism spectrum disorder in the Mediterranean region (Valencia, Spain). Nutr Neurosci. 2015 May 28.

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Marí-Bauset S, Llopis-González A, Zazpe I, Marí-Sanchis A, & Suárez-Varela MM (2015). Nutritional Impact of a Gluten-Free Casein-Free Diet in Children with Autism Spectrum Disorder. Journal of autism and developmental disorders PMID: 26428353