Food and the Intestine: Friends from day one

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BY: JOHN GLEESON, PhD

Few friendships are cultivated from birth, but an essential  relationship between food and the intestine starts from the very day you are born. If your intestines aren’t functioning properly (possibly due to a disease) then you’re less likely to absorb nutrients and digest food. And recently, a lot of marketeers have spread a lot of misinformation about foods and food components which can improve or impact intestinal health. Just Google “intestinal health” and you’ll encounter a plethora of hogwash, snake oil, and literal crap (well, we are talking about the gut here people). So consider me your Ms. Frizzle, let’s hop on the Magic Gut Bus and get a better understanding of your intestines and the impact of the food you eat, which I’ve previously published in Nutrition Bulletin 1.

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The intestinal barrier

Much like the walls of Helms Deep from Lord of the Rings, every kingdom needs to protect itself from outside invaders. The intestinal epithelial cells act as bricks in the wall and are held together by proteins called Tight Junctions instead of hardy industrial cement. And, of course, no castle realm would be complete without a mucus layer moat. In disease states like inflammatory bowel disease (IBD) and coeliac disease, this barrier is affected and the walls… well…aren’t the best at doing their job. If you want to understand more about intestinal diseases, Diet vs. Disease did a great blog post on this. One of these families of Tight Junction proteins is the claudin family, and in Crohn’s disease, ulcerative colitis, irritable bowel syndrome, and coeliac disease, claudin-2 is increased causing “porosity” of the intestine 1,2,3. So it’s understandable that a lot of nutritionists, dietitians, and food scientists are interested in finding food products that help restore barrier integrity and/or prevent damage.

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Probiotics

The functional food that has received the most attention with it’s gut restorative abilities are your friendly neighbourhood probiotic bacteria. It has been pretty well established that pathogenic bacteria such as E. coli, Salmonella typhimurium and Clostridium perfringens impact the intestinal barrier through a myriad of mechanisms which ultimately open these Tight Junctions in the intestinal walls4-6. Thankfully, probiotic bacteria, in particular the genus Lactobacillus, have shown promise in helping close these openings induced by “bad bacteria”. Lactobacillus rhamnosus GG7 and Lactobacillus plantarum8 were able to prevent intestinal damage in animal models, but this hasn’t been shown to   fully in humans. A recent review of probiotics in gastrointestinal disorders noted some promising human trials but the authors comment “additional studies are needed to make conclusive inference on the efficacy of probiotics for colitis, Crohn’s disease, and liver disorders” 9. Basically… we still don’t know if probiotics can be  a therapeutic treatment.

Food-components

Besides probiotics, a number of bioactive components such as docosahexaenoic acid and eicosapentaenoic acid (omega-3 fatty acids found in fish oil) have been investigated to see if they can restore the integrity of the intestinal barrier10. But this data has only been found in cell models of the intestine. Resveratrol (our friendly neighbourhood wine polyphenol) has been shown to reduce the amount of inflammation present in a mouse model of Crohn’s disease11, but the solubility of resveratrol is pretty poor in both water and oil so making this a viable treatment would probably require nanoparticles or an alcohol-based solution (which I’m personally super down for). Unfortunately, alcohol also damages the intestinal tissue, and alcoholics have reported increased intestinal “leakiness”12. Protein fragments from Soybean (VPY and KPV) have also shown a lot of promise in reducing inflammation in a number of cellular and animal models of inflammation13, but as of yet have not reduced clinical trials in humans.

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Conclusions

So what’s on the horizon? Well there’s a huge amount of promise for probiotics bacteria, and food components that could improve the intestinal barrier especially for people with IBD, IBS and Coeliac disease. But at the moment, I heartily recommend taking the information plastered all over the internet (except mine of course) with a pinch of salt, a slice of lime and a shot of tequila.

References
  1. Gleeson JP. (2017) Diet, food components and the intestinals barrier. Nutrition Bulletin 42:2, 123-131.
  2. Hu C-AA, Hou Y, Yi D et al. (2015) Autophagy and tight junction proteins in the intestine and intestinal diseases. Animal Nutrition 1: 123–7.
  3. Landy J, Ronde E, English N et al. (2016) Tight junctions in inflammatory bowel diseases and inflammatory bowel disease associated colorectal cancer. World Journal of Gastroenterology 22: 3117–26.
  4. Barmeyer C, Schulzke JD & Fromm M (2015) Claudin-related intestinal diseases. Seminars in Cell & Developmental Biology 42: 30–8.
  5. Kim HJ, Li H, Collins JJ et al. (2016) Contributions of microbiome and mechanical deformation to intestinal bacterial overgrowth and inflammation in a human gut-on-a-chip. Proceedings of the National Academy of Sciences 113: E7–15
  6. Eichner M, Augustin C, Fromm A, Pointek A, Walther W, Bucker R, Fromm M, Krause G, Schulzke JD, Gunzel D, Pointek J. (2017) In colon epithelia, Clostridium perfringes enterotoxin causes focal leaks by targeting claudins which are apically accessible due to tight junction derangement. J Infect Dis, In press.
  7. Wang Y, Kirpich I, Liu Y et al. (2011) Lactobacillus rhamnosus GG Treatment Potentiates Intestinal Hypoxia-Inducible Factor, Promotes Intestinal Integrity and Ameliorates AlcoholInduced Liver Injury. The American Journal of Pathology 179: 2866–75.
  8. Chen HQ, Yang J, Zhang M et al. (2010) Lactobacillus plantarum ameliorates colonic epithelial barrier dysfunction by modulating the apical junctional complex and PepT1 in IL-10 knockout mice. American Journal of Physiology 299: 1287–97.
  9. Parker EA, Roy T, D’Adamo CR, Wieland LS. (2017). Probiotics and gastrointestinal conditions. Nutrition, In press.
  10. Mokkala K, Laitinen K & Royti o H (2016) Bifidobacterium lactis 420 and fish oil enhance intestinal epithelial integrity in Caco-2 cells. Nutrition Research 36: 246–52.
  11. Rahal K, Schmiedlin-Ren P, Adler J et al. (2012) Resveratrol has antiinflammatory and antifibrotic effects in the peptidoglycanpolysaccharide rat model of Crohn’s disease. Inflammatory Bowel Diseases 18: 613–23
  12. Wang Y, Tong J, Chang B et al. (2014) Effects of alcohol on intestinal epithelial barrier permeability and expression of tight junction-associated proteins. Molecular Medicine Reports 9: 2352–6.
  13. Kovacs-Nolan J, Zhang H, Ibuki M et al. (2012) The PepT1-transportable soy tripeptide VPY reduces intestinal inflammation. Biochimica et Biophysica Acta (BBA) – General Subjects 1820: 1753–63.

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