Leaky gut – The hype about hyperpermeability

You may have heard the term ‘Leaky gut’ being batted around, but what does it actually mean? Is it really a thing?

Yes – it is a thing! Leaky gut is the colloquial term used to describe the increased permeability of the gut wall, or ‘intestinal hyperpermeability'.

One of the most important functions of our gut is its essential role as a barrier to the environment. This structural barrier encompasses an epithelial layer, and a mucus layer which our intestinal microflora adhere to. The top layer (the epithelium) contains tight junctions, which regulate the movement of water and other small molecules in and out of our digestive tract, opening and closing when required. ¹ However, certain factors can also unfavourably open, and disrupt these tight junctions, such as infections and inflammation, as well as foods, such as those containing gluten.

How do you know if you have leaky gut? Without testing (a holistic doctor or a nutritional therapist can recommend the right test), it is difficult to know for sure, but there are certain symptoms and conditions that are associated with it. Because the functioning of this barrier is vast, and involves regulating our metabolism, immunity, digestion, absorption, nervous and endocrine function,² disturbance to this barrier has been linked to many health conditions, such as allergies³, autism and autoimmunity⁴ (e.g. coeliac disease), to name a few. You may also suffer with diarrhoea or constipation, frequent headaches, food intolerances, skin rashes or other skin-related problems, recurrent infections or problems with memory and concentration.

Even if you are not sure if you have it or not, supporting a healthy gut lining and preventing leaky gut can only benefit your health! So what can you do?

Start with your diet

The food we consume comes into direct contact with the cells lining our digestive tract, therefore, quality is everything. For a sensitive or inflamed digestive tract, certain foods can be further irritating, such as dairy and chilli. In these circumstances, focusing on easily digestible, soothing foods, like soups, bone broths, and smoothies, can be beneficial.

Is gluten an issue?

As mentioned previously, gluten containing foods can contribute to intestinal hyperpermeability. Zonulin is a protein that acts as a gatekeeper of tight junctions in the small intestine, increasing permeability.⁵ Its secretion is heightened by the presence of gluten.⁶ Therefore, the first point of call for addressing a leaky gut could be adopting a gluten free diet, directly excluding this stimulant.

However, it’s not just gluten that can have that effect. Lectins - the proteins found in a wide range of legumes and vegetables, especially if not cooked or prepared properly, can bind to the surface of cells lining the intestine, and inhibit intestinal cell repair, potentially keeping tight junctions open.⁷

Include gut-healing nutrients in your daily regime

If the lining of the digestive tract is damaged, the body will require an increased supply of nutrients that aid repair, as well as the building blocks for connective tissue. There are many that we could include, but the following are our favourites:

* Glutamine – the most abundant non-essential amino acid in human muscle. Glutamine supplementation can protect against inflammation, improve intestinal barrier function and help to reduce intestinal permeability.^8,9,10

* Collagen – The gut wall contains collagen fibres that strengthen the whole structure. Currently, there appears to be a research gap in relation to collagen supplementation and leaky gut, but some preliminary studies are beginning to highlight the use of type 1 collagen for intestinal cell maintenance.¹¹

* Nucleotides – these organic compounds form the building blocks of DNA, which is essential for cell division and repair.¹² Dietary sources of nucleotides include organ meats and seafood.

* Zinc – encourages healing,¹³ and reduces gut inflammation.^14,15 Zinc has also been shown to reduce gut permeability via actively having a positive effect on tight junctions.^16,17

* N-Acetyl Glucosamine (N.A.G) – an essential components of all body tissues, including the digestive tract lining. It promotes growth and intestinal repair.¹⁸ N.A.G. can also bind to lectins, rendering them inactive, and therefore unable to bind to cell surface membranes.¹⁹

* Antioxidants – such as vitamin C, can increase collagen synthesis.^20,21 Antioxidant therapy has also been proposed as beneficial for digestive conditions such as IBD via mopping up free radicals, which can be produced via gut bacteria, as well as via reducing inflammation.²²

* Probiotics – our gut bacteria attach to the mucus layer of the intestinal barrier, working to support gut integrity.^23,24 In fact, alterations to our gut microflora can actually cause leaky gut. Therefore, probiotic supplementation or increasing the intake of probiotic foods can be beneficial and has been linked to a reduction in intestinal inflammation and permeability risk, especially during endurance training.²⁵

Is your lifestyle the problem?

Diet and supplementation are important, but if your lifestyle is at the core of your digestive issues, it is key to sort out some of those underlying drivers to achieve better results in the long run. Many lifestyle factors can further increase gut permeability. These include medications, such as NSAIDS (e.g. ibuprofen) and aspirin, alcohol and stress.^26,27,28 In addition, strenuous exercise is also associated with the damaging of the gut wall, increasing permeability.²⁹ Therefore, incorporating particular activities into daily life, such as rest days between intensive exercise sessions and meditation to help with stress management, could be incredibly useful.

These are just a few of the key steps that can be considered when trying to tackle intestinal hyperpermeability. Our gut health is so important and linked to many other body systems, therefore keeping it healthy and functioning properly is integral for ensuring and maintaining our overall health.

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¹ Fasano A. Zonulin, regulation of tight junctions, and autoimmune diseases. Ann N Y Acad Sci. 2012; 1258 (1): 25-33.

² Lipski E. Digestive Wellness: Strengthen the Immune System and Prevent Disease Through Healthy Digestion. 2011. 4th Edn. New York: McGraw-Hill.

³ Price D, et al. Nuts ‘n’ guts: transport of food allergens across the intestinal epithelium. Asia Pac Allergy. 2013; 3 (4): 257-65.

⁴ Visser J et al. Tight junctions, intestinal permeability, and autoimmunity: celiac disease and type 1 diabetes paradigms. Ann N Y Acad Sci. 2009; 1165: 195-205.?

⁵ Fasano A. Intestinal permeability and its regulation by zonulin: diagnostic and therapeutic implications. Clin Gastroenterol Hepatol. 2012; 10 (10): 1096-100.

⁶ Fasano A. Zonulin and its regulation of intestinal barrier function: the biological door to inflammation, autoimmunity, and cancer. Physiol Rev. 2011; 91(1):151-75.

⁷ Miyake K, et al. Lectin-Based Food Poisoning: A New Mechanism of Protein Toxicity. Steinhardt R, ed. PLoS ONE. 2007;2(8):e687.

⁸ Quan et al. Effect of glutamine on change in early postoperative intestinal permeability and its relation to systemic inflammatory response. World J Gastroenterol. 2004. 10 (13): 1992-4

⁹ Rapin J. R, Wiernsperger N. Possible links between intestinal permeablity and food processing: a potential therapeutic niche for glutamine. 2010. Clinics:65.

¹⁰ Rapin et al. Possible Links between Intestinal Permeability and Food Processing: A Potential Therapeutic Niche for Glutamine. Clinics. 2010; 65(6).

¹¹ Jabaji Z et al. Type I Collagen as an Extracellular Matrix for the In Vitro Growth of Human Small Intestinal Epithelium. 2014 PLoS ONE 9(9).

¹²Hess JR, Greenberg NA. ‘The role of nucleotides in the immune and gastrointestinal systems: potential clinical applications

¹³ Schwartz et al. Zinc and Skin Health: Overview of Physiology and Pharmacology. Dermatologic Surgery. 2005; 31: 837-47.

¹⁴ Greuter T et al. Low serum zinc levels predict presence of depression symptoms, but not overall disease outcome, regardless of ATG16L1 genotype in Crohn’s disease patients. Therapeutic Advances in Gastroenterology. 2018

¹⁵ Skrovanek S et al. Zinc and gastrointestinal disease. World Journal of Gastrointestinal Pathophysiology. 2014;5(4):496-513..

¹⁶ Sturniolo GC et al. Effect of zinc supplementation on intestinal permeability in experimental colitis. J Lab Clin Med. 2002 May;139(5):311-5.

¹⁷ Sturniolo GC et al. Zinc supplementation tightens "leaky gut" in Crohn's disease. Inflamm Bowel Dis. 2001 May;7(2):94-8.

¹⁸ Salvatore et al. Pilot study of N-acetyl glucosamine, a nutritional substrate for glycosaminoglycan synthesis, in paediatric chronic inflammatory bowel disease. Aliment Pharmacol Ther. 2000; 14(12): 1567-79.

¹⁹ Patil et al. Structural Investigation of a Novel N-Acetyl Glucosamine Binding Chi-Lectin Which Reveals Evolutionary Relationship with Class III Chitinases. PLoS One. 2013; 8 (5): e63779.

²⁰ Murad et al Proc.Natl.Acad.Sci.USA 78(5)

²¹ Boyera et al. Effect of vitamin C and its derivatives on collagen synthesis and cross-linking by normal human fibroblasts. Int J Cosmet Sci. 1998; 20 (3): 151-8.

²² Moura FA, et al. Antioxidant therapy for treatment of inflammatory bowel disease: Does it work? Redox Biology. 2015;6:617-639.

²³ Rao RK, et al. Protection and Restitution of Gut Barrier by Probiotics: Nutritional and Clinical Implications. Current nutrition and food science. 2013;9(2):99-107.

²⁴ Bischoff SC, et al. Intestinal permeability – a new target for disease prevention and therapy. BMC Gastroenterology. 2014;14:189.

²⁵ Roberts JD et al. An Exploratory Investigation of Endotoxin Levels in Novice Long Distance Triathletes, and the Effects of a Multi-Strain Probiotic/Prebiotic, Antioxidant Intervention. Nutrients, 2016: 8 (11).

²⁶ Purohit V et al. Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences: Summary of a Symposium. Alcohol (Fayetteville, NY). 2008;42(5):349-361.

²⁷ Collins SM. Stress and the Gastrointestinal Tract IV. Modulation of intestinal inflammation by stress: basic mechanisms and clinical relevance. Am J Physiol Gastrointest Liver Physiol. 2001 Mar;280(3):G315-8.

²⁸ Farhadi A et al. .Mucosal mast cells are pivotal elements in inflammatory bowel disease that connect the dots: stress, intestinal hyperpermeability and inflammation. World J Gastroenterol. 2007; 13 (22): 3027-3030.

²⁹ Roberts JD et al. An Exploratory Investigation of Endotoxin Levels in Novice Long Distance Triathletes, and the Effects of a Multi-Strain Probiotic/Prebiotic, Antioxidant Intervention. Nutrients, 2016: 8 (11).