Leaky Gut - EVERYTHING You Need to Know
I know, I know, the term ‘leaky gut’ sounds like something that happens after a dodgy vindaloo. But it’s just shorthand for what we call ‘intestinal hyper-permeability’, a hidden condition that is affecting millions of people and is responsible for a massive list of health conditions ranging from the less extreme bloating and gas, to eczema and skin rashes, to full-blown autoimmune conditions (1).
So let's clear the air and get a few things straight:
What is a leaky gut?
How did my gut get ‘leaky’?
How does leaky gut cause food sensitivities?
What about autoimmunity?
How can I get tested?
How do I plug-up my leaky gut and get back to my vibrant life?
What is Leaky Gut?
It is real, I promise! It is also really exciting that after more than 100 years and over 10,000 studies on intestinal permeability later, the medical community are starting to accept leaky gut as a condition exists.
To explain, we have to delve into a very simple anatomy lesson...
Diagram 1: Anatomy of the Small Intestine
Often referred to as the body’s second skin, the Epithelial Cells of the small intestine (i.e. the intestinal lining) are the fence between the inside of your intestines and your bloodstream. Their job is to control what is allowed access to your bloodstream, such as nutrients, and what is not allowed in, like pathogens, toxins and undigested food particles (macro-molecules). Like bouncers at a nightclub, epithelial cells are supposed to keep the bad guys out.
When you have a ‘leaky gut’, it’s like the doors are open between your intestines and your bloodstream. Macro-molecules, toxins and pathogens that normally aren’t allowed through, now flow freely into your bloodstream, making your immune system wake up and start fighting. This is called an inflammatory immune response and causes all sorts of symptoms.
This ‘leaking’ can happen in two ways:
Particles moving through your damaged epithelial cells (transcellular)
Particles moving between the loosened tight junctions that hold your epithelial cells together (paracellular)
Diagram 2: Anatomy of a Leaky Gut
How did my gut get ‘leaky’?
There are a large number of likely causes of leaky gut meaning you can have one or more triggers that increase your risk of suffering from this issue. Some cause an increase in transcellular permeability, while others are responsible for an increase in paracellular permeability, or both.
Here is a list of the most commonly listed stressors that lead to a leaky gut:
1. Poor Diet
While some foods can be extremely nourishing, others can cause serious damage to your intestinal lining (i.e. epithelial cells). The most common culprits are grains, dairy, allergens, processed and genetically modified foods. Read on for lots more detail about HOW they cause damage, it is really interesting and maybe not what you were thinking...
Grains: the issue with grains (and pseudo-grains like sneaky quinoa) can be described in the context of lectins, saponins and protease inhibitors - parts of the grain that protect it. They act as a natural defence for plants against outside invaders like mould or parasites. While this is good for plants, it’s bad news for your gut!
Protease inhibitors are designed to stop digestive enzymes doing their job of digesting the foods you eat, meaning undigested food particles get into your small intestine and can cause a biochemical reaction resulting in an excess of the enzyme ‘trypsin’, known to destroy the connections between cells (paracellular permeability). Check out these two articles by Dr Sarah Ballantyne if you want more of the science (HERE and HERE) or this one from Mark Sisson (HERE).
While gluten is the best known and most damaging example of lectin, other foods to look out for include rice, spelt, nightshades, legumes and soy as well as GMO foods (see below). Gluten is also thought to be one of the major contributors to increased levels of zonulin, a protein that opens up the spaces between the cells of the intestinal lining (4), making the gut leaky (paracellular permeability).
Dairy: Conventional cow’s milk is another food thought to contribute to leaky gut. The most common issues relate to the protein A1 casein and lactose, both of which the body has difficulty digesting (5, 6), leading to leaky gut.
Allergens: During an allergic reaction, inflammatory mediators are released and affect intestinal permeability (7, 8). We will talk about this more later on, but I really want you to know that food allergens and sensitivities are part of a continuing cycle where particles of food penetrate the intestinal lining, cause inflammation and contribute to further hyper-permeability, or leaky gut (9, 10).
Processed and GMO foods: Industrial food additives and preservatives increase intestinal permeability by loosening the tight junctions that hold the epithelial cells together and stop the gut from leaking (11, 12). Also, GMO foods tend to have high levels of lectins (see above), which are added into GMO foods to enhance pest and fungal resistance (13). Sugar is another common additive in processed food that is known to feed yeast, a huge contributor to leaky gut (see below).
These are the ‘bad guys’ that come in and declare war with your gut. Overgrowths of bacteria like Campylobacter or Salmonella (14), yeast like Candida (15) and parasites like H.Pylori (16) or Blastocystis hominis (17) are among the top culprits of a leaky gut. They cause an increase in inflammation as well as zonulin, the protein that opens up the tight junctions that hold the epithelial cells together, leading to an increase in paracellular (between the cells) intestinal permeability (4, 18, 19). The most common pathogens that cause a leaky gut are candida overgrowth, intestinal parasites and small intestine bacterial overgrowth (SIBO). If you have a leaky gut, these are one of the most important things to test for. Because, while you still have pathogens, you ain’t healing no leaky gut! I had a big list of these guys from travelling, eating dodgy foods and using lots of antibiotics to try and kill infections off - the perfect recipe for a leaky disaster zone in your gut.
It’s not just about the bad guys, not having enough good bacteria can also lead to a leaky gut. Studies have shown that the gut microbiome (all of the bugs in your gut - the good, bad and easily influenced guys - read more about this HERE in my post about the microbiome) plays a critical role in regulating intestinal permeability, a.k.a. leaky gut (20, 21). Not only do they keep harmful pathogens at bay, good bacteria like lactobacillus also help you break down harmful proteins such as the phytates that we talked about above (22, 23). With a really diverse microbiome (garden in your gut), many of the other risk factors listed here are unlikely to lead to a leaky gut because your body is able to fight them off. Unfortunately for us, with the overuse of antibiotics, alcohol, stress and processed foods, the average person’s microbiome is as poor as it’s ever been.
4. Toxins and medications
Toxins can cause leaky gut, both directly and indirectly. Studies suggest that toxins from alcohol cause intestinal permeability by blocking prostaglandins, things that help put out the fire from inflammation (24).
Environmental toxins such as mercury, pesticides, BPA and fluoride as well as pain relievers with Aspirin, Acetaminophen or Ibuprofen are also known to irritate the intestinal lining, create inflammation and lead to a leaky gut (25). More indirectly, medications such as antibiotics are known to reduce the numbers of good bacteria in your gut, creating the perfect environment where opportunistic bad bugs can overgrow, flourish and wreck your intestinal lining.
5. Emotional or mental stress
There is heaps of evidence indicating that stress is linked to leaky gut (26, 27, 28). This happens via the release of corticotropin-releasing factor (CRF) when your body is stressed, which can result in changes with intestinal permeability (26). The mechanics of this are complex so I won’t bore you with the detail here. Chronic stress is also known to suppress the immune system (29), reducing your body’s ability to fight-off pathogens, like fungus, bacteria and parasites, leading to more inflammation and a leaky gut.
6. Genetic predisposition
As with most things, some people are more susceptible to the stressors listed above than other people (30). For example, gluten, stress or a parasite may lead to a leaky gut in some people, but not in others.
How does leaky gut cause food sensitivities?
If undigested (macro) food molecules make it through your intestinal lining and into the bloodstream, your body will fight like hell to get rid of them. Once through the intestinal lining, these large food molecules travel via the bloodstream to the next line of defence - your liver. It is your liver’s job to clear out the waste in your bloodstream. When you have a leaky gut, your liver can’t keep up with its normal toxic load and all of these extra macro food molecules. So the really bad news is that these macro food molecules begin to circulate around your body, settling in various tissues of the body such as the brain, pancreas or even back to the epithelial cells of the small intestine (1).
Now the immune system will start to make antibodies against these macro food molecules because it thinks they are foreign invaders. What were previously harmless foods, are now treated like bad guys and greeted with an inflammatory immune response every time they enter the body. This is how you develop food sensitivities. The immune system becomes super-stimulated and over-reactive to foods that are not normally seen as dangerous (31).
For example, I once began to react to pineapple, a food I had eaten without any worries my whole life. All of a sudden, I began to experience nausea, cramping, bloating and stomach pains immediately after having pineapple. I was able to confirm at the time via an intestinal permeability test that I had a (very) leaky gut and an IgG food sensitivity to pineapple, amongst other real foods. No more pineapple glazed barramundi for a few months for me while I healed my leaky gut and gave it a rest from all of my inflammatory foods.
It’s important to remember that “true” food allergies (i.e. shellfish or peanut allergies from birth) are usually only one or two foods in a single person. So if you’re having sensitivities to more than a few foods, and are constantly restricting your diet to avoid feeling like crap, you likely have a leaky gut. A leaky gut will often result in food sensitivities to the foods you eat most often. Often, there is nothing wrong with those foods, it’s your gut that is the problem. Any undigested foods that are absorbed into your bloodstream, now initiate an immune response and an array of symptoms from bloating and cramps to fatigue and brain fog.
What about autoimmunity?
Human tissues have things called proteins and antigens that can look very similar to macro food molecules and pathogens. If your immune system is super-stimulated and generating antibodies to these macro food molecules and pathogens, then it can also be generating antibodies to the body’s own healthy tissues by mistake. This means that in some genetically predisposed people, antibodies are developed against your own tissues. And because these foreign molecules circulate in your bloodstream and end up in various parts of your body, the specific autoimmune condition developed depends on where those antigens end up (1). For example, if the inflammation develops in a joint, rheumatoid arthritis may develop. If antibodies attack the lining of the gut, you may get colitis or Crohn’s disease, and so on.
It was once believed that if triggered, an autoimmune disease could not be reversed. Fortunately, research has found something truly amazing: once hyperpermeability (leaky gut) is reduced, an autoimmune condition can be stopped and even go into remission (4).
Can I get tested?
Intestinal Permeability Test
We test for leaky gut using the NutriPATH Intestinal Permeability (IP) Test. It is a urine test that measures the ability of two sugar molecules, Lactulose and Mannitol, to permeate the intestinal lining, giving us an indication of your level of intestinal permeability or other issues with the structure of your gut lining.
NutriPATH IP Test Result - Example Extract
There are three things we are looking for that will explain the ‘phase’ or ‘type’ of leaky gut you have:
1. Mannitol Recovery: Mannitol is a mini sugar molecule and can move through the epithelial cells easily (transcellular uptake), making it a great marker for the health of cells. Increased or decreased transcellular uptake indicates damaged villi and microvilli, malnutrition from not absorbing nutrients and other associated conditions.
2. Lactulose Recovery: Lactulose is a large sugar molecule and is a good marker to see whether the tight junctions between the cells are tight or leaky because it can’t move through cells easily like mannitol. This makes lactulose a great marker for working out whether your tight junctions that hold your cells together are tight (paracellular transport). Increased levels of lactulose are bad and indicate permeability through the intestinal lining between the cells due to loosened tight junctions.
3. Lactulose:Mannitol Ratio: The lactulose:mannitol ratio is a secondary marker for leaky gut and is only used as an indicator when there is nothing to note from the above two measures. This ratio comes into play in the early stages of leaky gut, when one number is elevated compared to another which means things are starting to head in the direction of being leaky in the future.
If you think this sounds like you, get in touch and we can do some testing to figure out what is going on in your guts: CLICK HERE
Here is a video on the testing process in case you are interested:
Food Sensitivity Test
Food sensitivities affect up to 40% of the population and are a common symptom of leaky gut. Because food sensitivities are dose-dependent and can have delayed symptom onset of up to 48 hours, identifying them without testing can be extremely difficult. Also, because food sensitivities linked to leaky gut can include healthy, whole foods like fruits and vegetables, they are often overlooked by people as a potential cause of their symptoms. Who would've thought you could blame the humble pineapple for such horrid symptoms?!?
I do want to make a quick note here to say that food sensitivity testing is not perfect. There is currently no test on the planet that guarantees it will identify all of the foods you are sensitive to. For this reason we use your results as a guide for identifying “safe foods” for you while you are on a gut healing protocol.
NutriPATH IgG Food Sensitivity Test Result - Example Extract
ALCAT Intolerance Test Result - Example Extract
Testing options include the ALCAT Intolerance Test (blood draw) or the IgG Allergy Panel (dry blood spot), pictured above. Both tests are used to screen for specific foods that cause an immune reaction in the body. The IgG panel pictured above shows how reactive you are to a specific food that was tested. Any reaction higher than level 3 should be avoided for a minimum of three months, along with a gut healing protocol to help with healing your leaky gut.
When preparing for these tests, it is recommended you eat a large variety of foods in the two weeks prior to testing and include as many of the foods that are being tested in the specific panel you have chosen. If you don’t consume the food before the test, it may not be possible to detect the sensitivity.
If you are worried about food sensitivities and want to get tested: CLICK HERE
Here is a video on the IgG testing process (the most common food sensitivity test I use) in case you are interested:
How do I heal my leaky gut?
Successfully healing a leaky gut and reducing your food sensitivities requires an holistic approach focussed on fixing the root cause of your problems and supporting your body through the healing process. This means we are going beyond just temporary symptom relief. We want you to return to vibrant health so you can get back to the active and healthy lifestyle that leaky gut is holding you back from. We focus on five essential areas for fast and long-term healing:
The first step is to remove foods that are causing inflammation and those discussed above that can damage the gut. Here is a list of the main things to consider:
Food sensitivities identified via testing that are specific to you. Food sensitivities are like little bombs that go off in your gut and cause damage every time you eat them. They must be removed for a minimum of three months to give your gut space to heal.
The diet bad guys that we talked about above are next; gluten (and other grains that contain anti-nutrients), dairy, sugar, alcohol, processed and GMO foods.
Raw or cold foods: yep I said it. Raw foods can be terrible for a leaky gut. Why? Although they have lots of amazing nutrients, they are super hard to digest and place a really big strain on a gut that is already struggling and leaky. Avoid raw foods to give your gut space to heal.
So what can you eat? The Specific Carbohydrate Diet (SCD) can be a good place to start. You can also look at layering the low-FODMAP diet over this if you don’t get any relief after around 2-3 weeks on the SCD diet. Focus on organic products and aim for 2-3 litres of water (room temperature) or herbal tea to flush out toxins.
At the same time, it is important to start adding in cooked and fermented healing foods. Some of my favourites include:
Bone broth, which contains amino acids proline and glycine that help to support your tight junctions and heal the gut. Have this as a soup daily.
Fermented vegetables like sauerkraut and kimchi that have lots of organic acids, helping to grow gut healing probiotics such as lactobacillus plantarum. Start with one teaspoon and build up to a tablespoon daily.
Foods high in omega-3 fats like wild salmon, activated walnuts (if tolerated), chia seeds and flax oil which help with reducing inflammation. Try to include a small amount of omega-3’s in each of your main meals, such as one tablespoon of flax oil, two walnuts or one piece of salmon.
Coconut products due to their antimicrobial properties. Cook in coconut oil or add coconut milk to your sauces or in baked goods.
Blueberries are really high in antioxidants and fight off oxidative stress from free-radicals (i.e. damaging rascals) and give the body space to heal. Try adding ½ - 1 cup of blueberries to a warm smoothie at breakfast.
Rest is an essential component of any healing protocol and often overlooked. Know this: if you don’t give your body the rest it needs to heal, you will not get better! Ideally, go to bed before 10pm. 7-8 hours sleep each night is an absolute must. Good “sleep hygiene” means turning off those screens (phone, laptop and TV) and allowing one hour before sleep each evening to wind-down by reading a book, journaling, meditating or listen to relaxing music. Trust me, this practice alone will change your quality of sleep if you commit.
Too much or too intense exercise for those with a leaky gut can put added stress on the body and do more harm than good. While it’s always important to move your body, a more gentle approach, with exercise such as walking, yoga and restorative pilates will likely have the most positive impact on your healing. Once your gut is in better shape, you can return to all of the crazy-active things you love.
PLEASE READ! Removing and reducing stress on the body is a crucial part of any leaky gut healing protocol.
This applies to all three categories of stress:
Mental/emotional: implementing relaxation and stress reduction activities such as meditation or acupuncture
Physical: consider working with a chiropractor or other health professional to address any structural problems adding to your body’s overall stress
Hidden/internal: these are things like hormone imbalances, liver issues or pathogens that we need to test for and eliminate to stop the constant inflammation in your body. I can help you with this.
Through my study I have learnt that it is almost impossible to obtain all of the necessary nutrients we need for healing from our food alone. A pretty shocking truth and why we need to be smart and supplement. Supplements have two important functions in healing leaky gut; 1. Restoring balance within the gut, and 2. Repairing the damage to your intestinal lining. A few of my go-to supplements include:
Soil-based probiotics - look for a product that contains 50 billion units to help bring in some good strains of bacteria and fight off all the bad guys that are trying to take over. Take 1-2 daily with main meals.
Digestive enzymes allow the digestive system to have a rest while you are healing. They come in and break down food macro-molecules, decreasing the chance that these large molecules are damaging your gut wall. Look for brands that contain protease (breaks down protein), amylase (breaks down carbs) and lipase (breaks down fats). Have digestive enzymes with each of your main meals.
L-glutamine is a crucial amino acid that lines and protects the intestinal wall from irritants. It also provides intestine building-blocks to heal the gut lining (that work with proline from the bone broth). Take 2-5g of L-glutamine powder twice daily with food.
Quercetin helps to seal the gut by making the proteins that keep your tight junctions tight. Aim for 500 mg three times daily with your main meals.
Licorice root can be used to support the natural processes of the body that maintain the intestinal lining. Take 500 mg twice daily with food.
Aloe Vera juice fights inflammation and is very healing to the gut. Take 1/2 cup three times daily.
If you are interested in getting tested for leaky gut or food sensitivities and having a personalised healing protocol developed specifically for you, please head to the Work With Us page to learn more about how we work online with clients in many countries to test for and treat the various root causes of IBS symptoms and other GI conditions.
Arrieta, M. C., Bistritz, L., & Meddings, J. B. (2006). Alterations in intestinal permeability. Gut, 55(10), 1512–1520. (Link)
Pusztai, A., et al. (1993). Antinutritive effects of wheat germ agglutinin and other N-acetylglucosamine-specific lectins. Br J Nutr, 70(1), 313-321. Link
Podolak, I., Galanty, A., & Sobolewska, D. (2010). Saponins as cytotoxic agents: a review. Phytochemistry Reviews, 9(3), 425–474. Link
Fasano, A. (2011). Zonulin and Its Regulation of Intestinal Barrier Function: The Biological Door to Inflammation, Autoimmunity, and Cancer. Physiol Rev, 91(1), 151-175. Link
Pal, S., Woodford, K., Kukuljan, S., & Ho, S. (2015). Milk Intolerance, Beta-Casein and Lactose. Nutrients, 7(9), 7285–7297. Link
Wang, Y., et al. (1998) The genetically programmed down-regulation of lactase in children. (1998). Gastroenterology, 114(6), 1230-6. Link
Perrier, C. and Corthésy, B. (2011), Gut permeability and food allergies. Clinical & Experimental Allergy, 41: 20–28. Link
Andre, F., et al. (1991). Digestive Permeability to Different-Sized Molecules and to Sodium Cromoglycate in Food Allergy. Allergy and Asthma Proceedings,12(5), 293-298. Link
Heyman, M. Gut barrier dysfunction in food allergy. (2005). European Journal of Gastroenterology & Hepatology, 17(12), 1279-1285. Link
Barau, E., Dupont, C. (1990). Modifications of Intestinal Permeability During Food Provocation Procedures in Pediatric Irritable Bowel Syndrome. Journal of Pediatric Gastroenterology & Nutrition, 11(1), 72-77. Link
Lerner, A., Matthias, T. (2015). Changes in intestinal tight junction permeability associated with industrial food additives explain the rising incidence of autoimmune disease. Autoimmunity Reviews 14 (6), 479–489. Link
Rapin, J. R., & Wiernsperger, N. (2010). Possible Links between Intestinal Permeablity and Food Processing: A Potential Therapeutic Niche for Glutamine. Clinics, 65(6), 635–643. Link
Rhodes, J. M. (1999). Genetically modified foods and the Pusztai affair. British Medical Journal, 318(7193), 1284. Link
Spiller R., et al. (2000) Increased rectal mucosal enteroendocrine cells, T lymphocytes, and increased gut permeability following acute Campylobacter enteritis and in post-dysenteric irritable bowel syndrome. Gut, 47(6), 804-11. Link
Yamaguchi, N., et al. (2006). Gastrointestinal Candida colonisation promotes sensitisation against food antigens by affecting the mucosal barrier in mice. Gut, 55(7), 954–960. Link
Di Leo, V., et al. (2005). Effect of Helicobacter pylori and eradication therapy on gastrointestinal permeability. Implications for patients with seronegative spondyloarthritis. The Journal of Rheumatology, 32(2), 295-300. Link
Dagcia, H., et al. (2002). Protozoon infections and intestinal permeability. Acta Tropica, 81(1), 1–5. Link
El Asmar, R., et al. (2002). Host-dependent zonulin secretion causes the impairment of the small intestine barrier function after bacterial exposure. Gastroenterology, 123(5), 1607-15. Link
Zuckerman, M., Watts, M., Bhatt, B., Ho, H. (1993) Intestinal permeability to [51Cr]EDTA in infectious diarrhea. Digestive Diseases and Sciences, 38(9), 1651-1657. Link
Kelly, J., et al. (2015). Breaking down the barriers: the gut microbiome, intestinal permeability and stress-related psychiatric disorders. Frontiers in Cellular Neuroscience, 9, 392. Link
Earley, ZM., et al. (2015) Burn Injury Alters the Intestinal Microbiome and Increases Gut Permeability and Bacterial Translocation. PLoS ONE 10(7): e0129996. Link
Askelson, T. E., et al. (2014). Evaluation of Phytate-Degrading Lactobacillus Culture Administration to Broiler Chickens. Applied and Environmental Microbiology, 80(3), 943–950. Link
Kohl, K.D., et al. (2014). Gut microbes of mammalian herbivores facilitate intake of plant toxins. Ecology Letters, 17(10), 1238-46. Link
Purohit, V., et al. (2008). Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences: Summary of a Symposium. Alcohol (Fayetteville, N.Y.), 42(5), 349–361. Link
Zamora, S., et al. (1999). Intestinal permeability before and after ibuprofen in families of children with Crohn's disease. Canadian Journal of Gastroenterology & Hepatology, 13(1), 31-6. Link
Rodiño-Janeiro, B., et al. (2015). Role of Corticotropin-releasing Factor in Gastrointestinal Permeability. Journal of Neurogastroenterology and Motility, 21(1), 33–50. Link
Gareau, M. (2008). Pathophysiological mechanisms of stress-induced intestinal damage. Current Molecular Medicine, 8(4), 274-81. Link
Collins, S. (2001). Stress and the Gastrointestinal Tract IV. Modulation of intestinal inflammation by stress: basic mechanisms and clinical relevance. Am J Physiol Gastrointest Liver Physiol, 280(3), G315-8. Link
Segerstrom, S. C., & Miller, G. E. (2004). Psychological Stress and the Human Immune System: A Meta-Analytic Study of 30 Years of Inquiry. Psychological Bulletin, 130(4), 601–630. Link
Hilsden, R. (1996). Intestinal permeability changes in response to acetylsalicylic acid in relatives of patients with Crohn's disease. Gastroenterology, 110(5), 1395-403. Link
Heyman, M. (2005). Gut barrier dysfunction in food allergy. Eur J Gastroenterol Hepatol, 17(12), 1279-85. Link