dietary microparticles and intestinal response

Dietary microparticles and their impact on tolerance and immune responsiveness of the gastrointestinal tract
Powell et al (2007 ) British Journal Nutrition Dietary microparticles and their impact on tolerance and immune responsivenes of the gastrointestinal tract. vol 98, supplement S59-63
This is an interesting and novel approach and an important contribution to a theory for the aetiology of Crohn’s disease. Crohn’s disease is said to be a new condition. Who knows? One theory was that toothpaste and other sources of indigestible particles is a factor. So the authors have reviewed the evidence.
Dietary microparticles are non-biological bacterial-sized particles of the gastrointestinal lumen that occur due to endogenous formation (calcium phosphate) or following oral exposure (exogenous microparticlc). In the UK. about 40 mg (10 x12) of exogenous microparticles are ingested per person per day, through exposure to food additives, pharmaceutical/supplement excipients or toothpaste constituents.
Once ingested, exogenous micro particles are unlikely to pass through the gastrointestinal tract without adsorbing to their surfaces some ions and molecules of the intestinal lumen. Both entropy and ionic attraction drive such interactions. Calcium ions are especially well adsorbed by dietary micro particles which then provide a positively charged surface for the attraction (adsorption) of other organic molecules such as lipopolysaccharides, peptidoglycans or protein antigen from the diet or commensal flora.
The major (but not only) sites of microparticle entry into intestinal tissue arc the M-cell rich lymphoid aggregates (termed Peyer’s patches in the small bowel). Indeed, it is well established that this is an efficient transport route for non-biological microparticles although it is unclear why.
The authors suggest that this pathway exists for “endogenous microparticles” of calcium phosphate. with immunological and physiological benefit, and that “exogenous dietary microparticles”, such as titanium dioxide and the silicates, hijack this route.
This overview focuses on what is known of these microparticles and outlines their potential rule in immune tolerance of the gut (endogenous microparticlesl or immune activation (exogenous microparticles) and inflammation of the gut.

Martin Eastwood
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