The “gut”, or more officially the human gastrointestinal system, is the section of your digestive tract where the final stages of food breakdown and absorption of water and nutrients take place. In order for absorption to occur, the intestinal wall must act as a sieve, allowing water and nutrients to move through the wall into the bloodstream, while toxins and undigested materials stay in the intestine, destined to be excreted from the body. Unfortunately, sometimes the holes in the intestinal wall (called “tight junctions”) loosen, thereby allowing toxins into the bloodstream along with nutrients and water. This phenomenon is called “leaky gut” or “intestinal hyperpermeability”.
Because the health of the gut is so connected with the function and efficiency of many other body systems, leaky gut may be the underlying problem behind a number of symptoms, diseases, and discomforts. Here, we will explore how leaky gut may present itself, what may be causing it, and how you can change your diet and lifestyle to improve the health and function of your digestive system.
What are the symptoms of a leaky gut?
If bacteria and other toxins enter the bloodstream from the gut, it can cause widespread inflammation and may trigger an immune response . This inflammation and immune response can present as physical symptoms such as swelling, sudden sensitivities to certain foods, skin problems (such as acne, rashes, and eczema), and digestive issues (such as bloating, diarrhea, or constipation) .
Other studies have suggested that leaky gut may cause or contribute to brain-related symptoms such as headaches, migraines, confusion, difficulty concentrating, fatigue, mood swings, or even mood disorders . It should be noted that the body of evidence supporting the importance of the gut-brain axis is quickly growing and gaining more attention in the realm of health research, but it is yet to be fully understood.
It has also been suggested that there are some food allergies and a number of chronic diseases where intestinal hyperpermeability is a key factor in disease development, as when increased permeability is prevented or fixed, the disease does not develop . Two examples of such diseases are type 1 diabetes  and inflammatory bowel disease .
What causes a leaky gut?
As leaky gut is a fairly new concept in the scheme of medical diagnoses, there may be multiple causes that have not yet been uncovered. So far, the only confirmed cause is related to a chemical called zonulin. Zonulin is the only known human-made protein to affect the action of tight junctions (the holes in the intestinal wall) . More zonulin means tight junctions loosen, causing leaky gut. So how can we regulate how much zonulin is made by the body?
Some people are predisposed genetically to make more zonulin, but zonulin release can be triggered by two known environmental factors: certain bacteria and gluten. This fact is supported by the finding that people with celiac disease (an autoimmune condition exacerbated by gluten) tend to over-express gluten receptors that trigger the release of zonulin in their intestinal cells . Therefore more zonulin than normal is released in celiac patients, triggering hyperpermeability, and an associated immune response. This is not to say that leaky gut only occurs in cases of celiac disease, it is just evidence for the mechanism of action triggered by gluten.
There is also evidence that alcohol and refined sugar consumption likely has a negative effect on the permeability of tight junctions [6,7].
Can a leaky gut be healed?
If zonulin mediates tight junctions, and bacteria and gluten can regulate zonulin release, logic says pushing the balance of the gut bacterial population toward probiotic species and reducing the amount of gluten in the diet should support the proper barrier function of the intestinal wall. There is evidence that this works. Even those with celiac disease have shown significant recovery from leaky gut in a year or less by avoiding all gluten in the diet . This is a great place to start.
There are other measures that can be taken to support the health of your gut and tight junctions, and yes, in many cases, a leaky gut can be healed. Gluten may not be the only triggering food, so your healthcare provider may recommend a low FODMAP diet (“read more about low FODMAP diets here”) to rule out food groups that may be triggering your individual immune system. This includes limiting or eliminating sugar and alcohol intake.
To tackle any dysbiosis in the gut (an imbalance of harmful bacteria) that could be the cause of a zonulin increase, you may consider starting a daily prebiotic and probiotic regimen. While probiotics are foods or supplements containing bacterial species that support intestinal health, prebiotics are foods or supplements that feed the probiotics, giving them a stronger chance of thriving in the gut (read more about probiotics and prebiotics here). Just as a problem like leaky gut can translate to symptoms throughout the body, a healthy, healed gut can translate to benefits throughout the body. The microbial populations that inhabit your gut play a role in the health of your digestion, your nutritional health, your immune system, and even your mental health.
Probiotic foods and supplements are not the only way to change the balance of microbial populations. Stress has been shown to have a direct relationship with the gut microbiome, so taking steps for self-care and stress relief may be an important part of your gut-healing .
Can I prevent a leaky gut?
Again, some people may be genetically predisposed to producing more zonulin than others, thereby increasing the likelihood of developing a leaky gut. While it is not guaranteed that a leaky gut can be prevented in any person, there are measures you can take to decrease the chances of hyperpermeability developing. With reference to the known causes above, limit sugar, alcohol, and gluten in the diet. Even if you do not suspect that you have a “gluten sensitivity” per se, too much gluten could lead to too much zonulin in any gut.
As stress is a factor in the health of your microbiome, continue to manage stress in a way that works for you, whether that be exercise, meditation, journaling, or talk therapy, among other techniques.
Last but certainly not least, prioritize the health of your gut microbiome. Make sure you have a healthy balance of probiotic species coming into your body daily, along with a high-prebiotic fiber diet to feed them and nurture their longevity.
- Arrieta, Marie-Claire, Lana Bistritz, and J. B. Meddings. “Alterations in intestinal permeability.” Gut 55.10 (2006): 1512-1520.
- Eske, Jamie. “What to know about leaky gut syndrome”. Medical News Today. August 21, 2019. https://www.medicalnewstoday.com/articles/326117
- Peters, Anneli, and Hartmut Wekerle. “Autoimmune diabetes mellitus and the leaky gut.” Proceedings of the National Academy of Sciences 116.30 (2019): 14788-14790.
- Lee, Sung Hee. “Intestinal permeability regulation by tight junction: implication on inflammatory bowel diseases.” Intestinal research 13.1 (2015): 11.
- Fasano, Alessio. “Intestinal permeability and its regulation by zonulin: diagnostic and therapeutic implications.” Clinical Gastroenterology and Hepatology 10.10 (2012): 1096-1100.
- Wang, Ying, et al. “Effects of alcohol on intestinal epithelial barrier permeability and expression of tight junction‑associated proteins.” Molecular medicine reports 9.6 (2014): 2352-2356.
- Bischoff, Stephan C., et al. “Intestinal permeability–a new target for disease prevention and therapy.” BMC gastroenterology 14.1 (2014): 189.
- Foster, Jane A., Linda Rinaman, and John F. Cryan. “Stress & the gut-brain axis: regulation by the microbiome.” Neurobiology of stress 7 (2017): 124-136.
- Duerksen, D. R., C. Wilhelm-Boyles, and D. M. Parry. “Intestinal permeability in long-term follow-up of patients with celiac disease on a gluten-free diet.” Digestive diseases and sciences 50.4 (2005): 785.