Thursday, 9 July 2015

Contrabiotics block intestinal pathogens

Foods can beneficially shape the gut microbiota through their prebiotic or antibiotic/antimicrobial effects. On the other hand some food components are able to block the adhesion and invasion of undesirable bacteria, thereby promoting their passage out the gut, and these have recently been termed contrabiotics 1. Contrabiotics have their most obvious application with infectious diarrhea and inflammatory bowel disease, but might also have some relevance in general dysbiosis and small intestinal bacterial overgrowth (SIBO).

A good contrabiotic should be able to largely resist digestion and therefore be active throughout the gut. This basically narrows things down to plant foods and their poorly digestible fibres, resistant starch or polyphenols 2. Below are some examples of food components reported to have contrabiotic effects in the research literature. This area is relatively unexplored, so there may well be many more examples to be discovered with common mechanisms of action.

Soluble fibres - It seems some non-starch polysaccharide (NSP) soluble fibres can act as contrabiotics. NSP from plantain and broccoli can block the intestinal adhesion and invasion of E. coli isolated from Crohn’s disease patients 1. Plantain has further been shown to block the adhesion of various major intestinal pathogens such as Salmonella spp., Shigella spp., enterotoxigenic E. coli and C. difficile 1. This effect has been suggested to arise from an NSP interaction with epithelial cells, which promotes electrogenic chlorine secretion and prevents adhesion of pathogens 1.

Resistant starch - Addition of starch to oral rehydration therapies aids recovery from cholera diarrhea 3. The intestinal pathogen Vibrio cholera has been shown to adhere to corn starch granules (as well as some other starches), which may promote its removal from the intestine 3. This effect is probably not limited to Vibrio cholera, since other pathogenic bacteria (e.g. A. hydrophila and E. coli ) were also found to adhere to corn starch, albeit to a lesser degree 3. An in vitro simulation of the gastrointestinal tract showed that adherence to corn starch is inhibited by bile and amylase activity (carbohydrate digestion) 4.

Polyphenols - Similar to resistant starch and fibre, most polyphenols are also poorly digested and pass down to the colonic microbiota 2. Cranberry phenolic compounds inhibit the adhesion of uropathogenic E. coli , which may contribute to its beneficial effects in urinary tract infections (UTIs) 5. This effect will likely be relevant in the intestine too. Another study showed that several common fruit polyphenols tended to preferentially inhibit the adhesion of intestinal pathogens (i.e. S. aureus and S. typhimurium) 6.

Misc foods - A few studies have identified foods with contrabiotic activity in an effort to reduce diarrhea in pigs. Adhesion of enterotoxigenic E. coli to the porcine intestinal mucosa was inhibited by wheat bran, casein glycomacropeptide (from cheese) and locust bean 7,8. Another study found pea and bean hulls to be effective 9.

References
1.         Simpson, H. L. & Campbell, B. J. Review article: dietary fibre-microbiota interactions. Aliment. Pharmacol. Ther. 42, 158–179 (2015).
2.         Cardona, F., Andrés-Lacueva, C., Tulipani, S., Tinahones, F. J. & Queipo-Ortuño, M. I. Benefits of polyphenols on gut microbiota and implications in human health. J. Nutr. Biochem. 24, 1415–22 (2013).
3.         Gancz, H., Niderman-Meyer, O., Broza, M., Kashi, Y. & Shimoni, E. Adhesion of Vibrio cholerae to granular starches. Appl. Environ. Microbiol. 71, 4850–5 (2005).
4.         Niderman-Meyer, O., Zeidman, T., Shimoni, E. & Kashi, Y. Mechanisms Involved in Governing Adherence of Vibrio cholerae to Granular Starch. Appl. Environ. Microbiol. 76, 1034–1043 (2009).
5.         De Llano, D. G. et al. Anti-Adhesive Activity of Cranberry Phenolic Compounds and Their Microbial-Derived Metabolites against Uropathogenic Escherichia coli in Bladder Epithelial Cell Cultures. Int. J. Mol. Sci. 16, 12119–30 (2015).
6.         Parkar, S. G., Stevenson, D. E. & Skinner, M. A. The potential influence of fruit polyphenols on colonic microflora and human gut health. Int. J. Food Microbiol. 124, 295–8 (2008).
7.         González-Ortiz, G. et al. Screening the ability of natural feed ingredients to interfere with the adherence of enterotoxigenic Escherichia coli (ETEC) K88 to the porcine intestinal mucus. Br. J. Nutr. 111, 633–42 (2014).
8.         Gustavo Hermes, R. et al. Casein glycomacropeptide in the diet may reduce Escherichia coli attachment to the intestinal mucosa and increase the intestinal lactobacilli of early weaned piglets after an enterotoxigenic E. coli K88 challenge. Br. J. Nutr. 109, 1001–12 (2013).
9.         Becker, P. M., van der Meulen, J., Jansman, A. J. M. & van Wikselaar, P. G. In vitro inhibition of ETEC K88 adhesion by pea hulls and of LT enterotoxin binding by faba bean hulls. J. Anim. Physiol. Anim. Nutr. (Berl). 96, 1121–6 (2012).



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