Updated: Oct 9, 2018
Anyone with digestive problems has no doubt jumped on google, and stumbled across leaky gut syndrome as a diagnosis. Leaky gut is becoming more common with the plethora of toxins, drugs, stress, pathogens, and poor quality foods etc, that we are all exposed to in modern society. Leaky gut can have devastating effects that can manifest throughout the body, and is a underlying factor in chronic illness, especially food allergy, cognitive decline, and autoimmune conditions.
The more correct term for leaky gut, is intestinal permeability. The intestinal wall has a surface area of approximately 400 square meters and is the first line of defense along our digestive tract to protect us from antigens, pathogens and toxins. As a result, an estimated 80% of our immune system is located along the digestive tract, and the gut lining requires 40% of the body's energy expenditure (to put that in perspective, the brain uses 20%). The intestinal lining is only one cell thick, and allows for the absorption of nutrients.
We can absorb nutrients through the cells (transcellular absorption) , or between the cells (paracellular), and so the gut is designed to be selectively permeable, but problems arise when barrier lining malfunctions, permeability becomes inappropriate, and this is what we refer to as leaky gut.
Between each cell we have toll gate like junctions that are designed to allow certain proteins through. Problems arise when the permeability is inappropriately increased, and we are no longer able to discern what enters the gut lining into the blood stream. Think of your gut lining like cheesecloth, all the tiny holes are designed to absorb TINY food particles. In proper digestion each food should be chopped up, broken down into smaller molecules, to be absorbed correctly through the intestinal lining. If there is a tear in the lining (the cheesecloth in this analogy), then larger molecules of undigested food particles erroneously enter through the intestinal lining and ignite an immune response.
Signs & symptoms of leaky gut
Many people accept gut distress as a mere fact of life. It’s not normal to experience symptoms of any kind, and symptoms are a key sign we are moving away from wellness, towards dis-ease. Given the importance of gut health for multiple bodily systems, signs and symptoms of leaky gut can, and often do occur outside of the gut. To heal the gut, the answer isn’t just to treat the symptom, but rather to hunt for the root cause of dysfunction, and use a multi-faceted approach to build up systemic health.
Indications that you may be suffering from poor gut health:
Bloating, gas, IBS, diarrhea
Auto immune diseases
Obesity, Metabolic syndrome or Diabetes
Food intolerance or allergies
Chronic pain & inflammation
Eczema, psoriasis, rosacea, acne
What's so bad about leaky gut?
As the contents of the gut (bacteria, toxins, food, yeast etc) leak into the bloodstream the immune system launches to attack the invaders. In the initial phase of leaky gut, it will cause you to have a non-specific chronic inflammation response. Chronic Inflammation is at the root of many disease processes, and the primary mechanism by which leaky gut results in poor health outcomes.
If the situation progresses, your immune system identifies inappropriate invaders by creating a targeted immune antibody response, to the invading antigen. This can lead to food intolerances or allergies to foods you have eaten your whole life with no problem!
Intestinal permeability is a precursor to developing an autoimmune disease. It occurs when your body may start to attack it's own tissue and you can even start to develop auto immune conditions like asthma, psorisis, hashimotos, celiac disease etc. It's now known that there are 3 priming factors that create auto-immune response:
Genetic susceptibility. The individual genetics will determine what type of autoimmune problem occurs if certain genes are activated. Genes load the gun, but the environment pulls the trigger, so it's important to optimise epigenetics by living a healthy lifestyle. Some people may develop antibodies that attack the gut lining as in celiac disease, or antibodies that attack the nerve myelin sheath as in myltiple schlerois, others develop antibodies to thyroid tissie as in hashimotos, it depends on your unique gene set, and where you are vulnerable to attack if leaky gut progressed.
Intestinal Permeability (leaky gut) allows the gut lining to be breached, which ignites systemic inflammation and eventually a targeted immune response.
Environmental trigger or insult: This may be a stressful event or chronic stress, toxin exposure, a food intolerance, a gut pathogen etc.
As the immune system becomes involved in digestion, immune system soldiers (antibodies), can travel anywhere in the body, and are initiated to fire against the enemy. These immune soldiers can create inflammation elsewhere in the body, and can even begin to attack the bodies own tissue! Many bacteria have antigenic sites that are similar to human tissue, and when they enter the bloodstream through a leaky gut, the body may attack both the endotoxins and our bodies own tissue during the defensive response. The process by which this happens is called molecular mimicry, whereby the body attacks it's own tissue because it looks similar (to the immune system) to the foreign particle. This is how arthritis, joint pain, low grade inflammation and chronic pain can be traced back to compromised gut health.
Leaky Gut Progression: Leaky Gut > Food Intolerance > Immune System Issues > Autoimmunity
Diseases associated with Intestinal Permeability
Because chronic inflammation and gut health is at the root of all disease, intestinal permeability is a significant problem that can manifest symptoms and disease processes anywhere in the body. You don't necessarily need to have gut specific symptoms, to have a problem with gut health. You can see how many patients and experts can miss the point by treating the symptoms of their condition, and never really identifying the root cause, which in many cases is poor gut health.
Irritable bowel disease
Cancer (esophageal, colorectal)
Skin conditions psoriasis
Parkinson’s, Alzheimer’s other neurological conditions
Autism, ADHD and other behavioral disorders
It's well established in the scientific literature that if you do have a leaky gut, you are likely to have a leaky brain, given that the same mechanisms that govern the gut barrier (zonulin protein), also regulate the blood brain barrier. Read more here about neurodegeneration and a 'leaky brain'.
Testing For Leaky Gut
Intestinal permeability is often both a cause and a result of gastrointestinal problems. It’s almost always a result of another condition like SIBO, parasites, infections like H. pylori, dysbiosis, food intolerances, etc, and thus the key is to identify and treat underlying mechanisms.
While it may be helpful to identify that intestinal permeability is present, it doesn't help pinpoint why it is happening. So for gut related problems, it's usually more helpful to run other tests that screen for pathogens, malabsorbtion, and inflammatory markers so as to eliminate the cause of intestinal permeability. In other words, don’t test for intestinal permeability until other issues are addressed.
There are a few ways to test for leaky gut. The most common is with a Lactulose/Mannitol Intestinal Permeability Screen. The lactulose-mannitol test involves drinking a sugar solution, and then measuring levels of these two sugars in the urine. Mannitol is a small particle which would pass through the cells, and a lower amount of mannitiol recovered in the urine, suggests that transcellular absorption is impaired. Lactulose is a larger molecule, and would pass between the cells, and an increase in lactulose absorption could indicated damage to the intestinal cells, impaired function of tight junctions.
Another testing method is an antigenic permeability screen which measures immune reactivity and permeability to three molecules which reflect intestinal barrier health, and help indicated whether the problem is occuring from damage to the intestinal epithelial cells, or due to antibody production to the proteins that regulate the intestinal barrier, Zonulin and Occludin.
Factors that lead to leaky gut
There are many factors that increase inappropriate intestinal permeability. Many of the below substances may be tolerated on a daily basis, but still cause daily damage to the intestinal lining. For example gliadin (gluten) is known to cause intestinal permeability in every single human regardless of whether they have celiac disease (confirmed in many studies.) The key is whether your unique physiology can keep up with, and repair the rate of damage as it occurs. But if you are eating gluten every meal, every day, and also subject to many of the below factors, and have an existing health condition, you may not be able to repair the damage as fast as it occurs.
Gluten (gluten upregulates zonulin the protein that regulates tight junctions between intestinal cells
Lifestyle factors: Stress, sleep deprivation, inappropriate physical activity
Lippopolysaccarides (LPS) (bacteria waste products)
Dysbiosis (dominance of pathogenic bacteria)
Non Steroidal Anti Inflammatory Drugs
The female birth control pill
acid blocking drugs (Proton Pump Inhibitors)
toxins: mold, heavy metals
Poor nutrition – inflammatory diet, lack of fermentable foods
Hygiene hypothesis: inadequate immune system stimulation during development
What to do about it
If you suspect you have a leaky gut you need to remove or reduce the contributing factors listed above, address underlying pathologies and rebuild a healthy gut ecosystem and lining.
Nutrition is key
Eat an anti-inflammatory diet rich in vegetables, quality meats, and fats. Avoid sugar, refined carbs, industrial nut and seed oils, processed or GMO foods and ideally avoid gluten containing grains. (Read more about why it's a good idea to avoid wheat products.) Bone broth is powerful for healing the gut and provides easily absorbed nutrients
Remove intolerant foods and potentially test for food allergies. This can be tricky with intestinal permeability as it's possible that every food you are eating may show up as an issue with intolerance testing, simply because the gut is leaky, and antibodies are being produced to all foods you are eating.
Investigate the root causes
Are you exposed to heavy metals, mold, or environmental toxins? Is chronic stress, poor sleep or inactivity an issue? Are you using and pharmaceutical drugs, alcohol or non steroidal anti inflammatory drugs that are causing you problems. Run a comprehensive stool test and screen for parasites, chronic infections, malabsorbtion issues or SIBO.
Rebuild gut health
Take prebiotic and probiotic supplements and eat fermented foods to establish a healthy gut ecosytem. The bacterial lining is protective and helps maintain a strong intestinal barrier. Take supplements of essential nutrients as your gut absorption is compromised and you may not be getting adequate nutrition from your food to heal your gut and quell inflammation. Nutrients like vitamins A, D, L-glutamine, short chain fatty acids, and zinc are important for gut barrier health.