Leaky Gut, also called increased intestinal permeability or gut permeability is when the tight junctions, which are the space between each of the cells that line the small intestine where nutrient absorption occurs, loosen a little and allow larger food particles and bacterial fragments into the bloodstream, potentially setting off an immune response and inflammatory reactions (1).
If you have a digestive disorder or gut health problems, it’s generally safe to assume you have a leaky gut. Likewise, leaky gut symptoms can present in a wide variety of ways across multiple body systems – not just in the digestive system.
Leaky Gut is associated with Irritable Bowel Disease (IBD), Crohn’s Disease (CD), multiple sclerosis (MS), rheutamoid arthritis (RA), type 1 diabetes (T1D), asthma, necrotizing enterocolitis, and autism spectrum disorder (2), as well as celiac disease, non-celiac gluten sensitivity, various skin disorders (if your skin has problems–then you have digestive problems), and more (3). However, we haven’t yet determined whether leaky gut is a cause or consequence of these disorders.
The Athlete Component
What is not as well known to a lot of the run long and run harder crowd is that sustained endurance activities, particularly the jostling and pounding that we do as runners, can and will cause a fair bit of leaky gut symptoms. If you consider the anatomy and physiology of this region of the digestive system, it’s easier to see why. Picture a person running a three (or four, or nine) hour marathon or ultra endurance race, or a series of training runs day after day and throughout weeks and months. The race and many of the runs leading up to the race is going to be a hard and a long effort (sometimes both), which we also will sometimes begin without feeling as recovered from the last effort as we’d prefer. Then, while running, we down any number of foods and food-like substances to provide fuel to sustain the effort and to “train the gut.” This fueling on the go is something the digestive and nervous systems are arguably not designed for. We’re “supposed to” be in rest and digest mode while we’re processing those calories. So utilizing them on the go is a stress to the system.
Then there’s the gut itself. At the small intestine, the cells between it and the bloodstream are approximately one cell thick. This is because this is the site where broken down nutrients move through to be transported to the liver and other regions of the body for use. It’s super thin so nutrients can get where they’re supposed to go. But one cell, and the space between it and the next one, is pretty easy to damage with jostling and stress. So even with a perfect diet, a hard long run (or even a hard shorter run) can cause some damage down there. This is why many people have digestive complaints for three to five days after a race or hard effort. That’s exactly how long it takes for the epithelial lining to turnover into completely new cells!
But what makes leaky gut become chronic, thus inviting long-term digestive (or widespread) symptoms?
There are several lifestyle factors that can also lead to and sustain a leaky gut including stress (a BIG one!), lack of sleep, eating inflammatory foods, alcohol, antibiotics, oral contraceptives, prescription medications, exposure to environmental toxins, and frequent use of NSAIDS such as ibuprofen. Likewise, nutrient deficiencies, poor digestion due to digestive enzyme deficiency, overeating in general, wrong ratio of dietary fats, gut microbe dysbiosis and (sometimes hidden) other food allergies can also contribute. Oofda! That’s a lot of factors that can be working against us.
That Villain Gluten and the Bacterial Connection
Dr. Alessio Fasano, a leading scientist who studies celiac disease and related pathologies, discovered an enterotoxin called zonulin a few years ago. Zonulin disassembles the tight junctions in the intestinal lining, allowing pathogens through and thus causing more intestinal permeability. Dr. Fasano’s research team found that zonulin release is primarily triggered by both bacteria and gliadin. Gliadin is part of the gluten protein complex (2.) Hence the reason many of us are either mildly or definitively reactive to gluten-containing foods, at least some of the time.
Before developing increased intestinal permeability, changes in the gut microbiota have also been shown to occur, which, given that zonulin release is often triggered by bacteria, suggests that the bacterial change occurs first, and then zonulin release assists the epithelial tight junctions to disassemble, leading the way for subsequent disorders or diseases to develop after sustained leaky gut-inflammatory reactions. It has been suggested that an environmental stimulus, (that list above including stress, gluten, a virus, inflammatory diet, etc.) first causes the change in the gut microbiota (2).
How to Heal
Healing chronic leaky gut often takes a many-pronged approach. We have to remove as many of the things that are causing it as it’s appropriate to. For those of us who aren’t willing to give up endurance athlete lifestyles, that means eating a diet appropriate for the individual, repletion of nutrient deficiencies, and lifestyle tactics (that stress relief component!) become particularly important.
Want to Know More?
A leaky gut is one of the primary categories of digestive imbalances I look for when working with individuals clinically with digestion-related and sometimes widespread symptoms. Often when we’re experiencing chronic GI distress, fatigue, and malabsorption of foods and nutrients, there will be imbalances in several categories, and we begin working on the areas that appear most pertinent. I shared more about this topic in the nervous system’s role in part 1, the immune response and subsequent inflammation in part two, gut microbes and dysbiosis in part three and the importance of chewing our food in part four.
And If you’re tired of dealing with your wonky GI symptoms and fatigue, and would like to get back to feeling and training well, I invite you to reach out to me for more personalized support.
1). Lipski, E. (2012). Digestive Wellness (4th ed). McGraw Hill: New York, NY.
2). Sturgeon, C. and Fasano, A. (2016). Zonulin, a regulator of epithelial and endothelial barrier functions, and its involvement in chronic inflammatory diseases. Tissue Barriers, 4(4). https://doi.org/10.1080/21688370.2016.1251384.
3) Kneessi, R. (2017). NUTR 635: Adverse Reactions to Food. [Lecture]. Maryland University of Integrative Health. Retrieved from: https://learn.muih.edu