The gut lining in the small intestine is just one cell-layer thick, but it has a big job—determining which nutrients get absorbed and which toxins, allergens, and microbes to keep out.

© Sebastian Kaulitzki | Dreamstime.com

The lining of your gut is directly related to the health of your whole body. This lining forms a crucial barrier between you and the outside world. In a sense, everything inside your gut is outside of you. Only a few very specific substances are normally allowed through, and the lining of your gut is what controls what gets through and what doesn’t. New research is showing that if the wrong things get through, you can wind up feeling tired all the time, experiencing depression symptoms, irritable bowel syndrome, food allergies, and more.

The gut lining is not a passive barrier. It actively senses what’s going on inside your gut, responds to what it senses, and even secretes various compounds that go on to control other bodily functions. The primary purpose of your gut lining, with all of its sensing, responding, and secreting, is to determine what nutrients get absorbed and what toxins, allergens, and microbes are kept out. Even though this lining is only one cell-layer thick, it protects your immune system and your entire body from the toxic environment in your gut by filtering out the good molecules from the bad molecules.

What Is Leaky Gut Syndrome?

Leaky gut syndrome refers to an abnormal increase in the permeability of the small intestine. Increased intestinal permeability, or leaky gut syndrome, is a pathological condition that occurs as part of many different diseases and syndromes, such as irritable bowel syndrome, chronic fatigue, and autoimmune diseases. If the lining of the small intestine is damaged, foreign compounds can escape from inside the small intestine into your bloodstream, making your immune system hyper-sensitive and even triggering auto-immune reactions.

Leaky gut can result from any irritation to the gut lining leading to increased permeability. Causes of leaky gut may include inflammation, imbalances of intestinal organisms, food allergies, maldigestion, and exposure to non-steroidal anti-inflammatories (NSAIDs), and alcohol.

Leaky Gut Syndrome Symptoms

1. You have irritable-bowel symptoms. Gut permeability is frequently increased in people with irritable bowel syndrome (IBS), especially if they suffer from diarrhea-predominant IBS. People with IBS who also have allergy symptoms like eczema, asthma, or hay fever have also been found to have leaky gut syndrome. The current working hypothesis is that the balance between “good” and “bad” gut bacteria gets disrupted, which activates the immune system and increases gut permeability. Probiotics can help restore a healthy balance of gut bacteria and eliminate leaky gut pain.
2. You’re tired all the time. Gut health and fatigue are linked to one another. Certain inflammatory compounds, called cytokines, are increased by leaky gut syndrome and are directly associated with fatigue. If you have chronic fatigue syndrome, your body likely produces high levels of immune cells directed against the toxins given off by unhealthy gut bacteria—a sign of leaky gut syndrome and a cause of inflammation. The severity of chronic fatigue symptoms has been found to directly correlate with blood levels of immune cells directed against toxin-generating gut bacteria. In plain English that means the more your unhealthy gut bacteria permeates through your leaky gut, the greater will be your feelings of extreme tiredness and chronic fatigue.
3. You have food allergies or intolerances. The link between food allergies and leaky gut syndrome is a vicious, two-way street. Increased passage of undigested food particles through the leaky gut leads to the development of food allergies. Conversely, allergic reactions to foods cause a transient increase in intestinal permeability. If this happens frequently, it may increase the number or severity of food allergies. In other words, leaky gut syndrome can cause you to become allergic to foods you may normally be able to digest perfectly well.
4. You have depression symptoms. Leaky gut and depression are very common together. It is now known that leaky gut activates the intestinal immune system to produce chemicals called cytokines that spread inflammation through your body. Inflammation is an important trigger for depression symptoms as well as other maladies such as fatigue, malaise, and pain.
5. You have an autoimmune disease. Leaky gut syndrome allows bacterial antigens capable of cross-reacting with your own tissues to escape the gut and enter your bloodstream, leading to auto-immune processes. The passage of certain antigens through the leaky gut barrier has been associated with autoimmune disorders such as rheumatoid arthritis, ankylosing  spondylitis, thyroid disease, myasthenia gravis, multiple sclerosis, inflammatory bowel disease (Crohn’s), and celiac disease.

Testing and Natural Treatment for Leaky Gut Syndrome

How do you know whether you do have a leaky gut that might be causing tiredness and depression, irritable bowel symptoms, or other chronic symptoms? Lab tests are available, along with proven natural treatments for healing leaky gut syndrome and returning your gut barrier function to normal.

Naturopathic and integrative physicians have been successfully treating leaky gut syndrome for years, and now, more than ever before, there is research available confirming the effectiveness of a number of natural therapies for leaky gut syndrome.

[1] Dunlop SP, Hebden J, Campbell E, Naesdal J, Olbe L, Perkins AC, Spiller RC. Abnormal intestinal permeability in subgroups of diarrhea-predominant irritable bowel syndromes. Am J Gastroenterol. 2006 Jun;101(6):1288-94.

[2] Fasano A. Leaky gut and autoimmune diseases. Clin Rev Allergy Immunol. 2012 Feb;42(1):71-8.

[3] Fasano A. Zonulin, regulation of tight junctions, and autoimmune diseases. Ann N Y Acad Sci. 2012 Jul;1258:25-33.

[4] Maes M. Inflammatory and oxidative and nitrosative stress pathways underpinning chronic fatigue, somatization and psychosomatic symptoms. Curr Opin Psychiatry. 2009 Jan;22(1):75-83.

[5] Maes M, Leunis JC. Normalization of leaky gut in chronic fatigue syndrome (CFS) is accompanied by a clinical improvement: effects of age, duration of illness and the translocation of LPS from gram-negative bacteria. Neuro Endocrinol Lett. 2008 Dec;29(6):902-10.

[6] Maes M, Mihaylova I, Leunis JC. Increased serum IgA and IgM against LPS of enterobacteria in chronic fatigue syndrome (CFS): indication for the involvement of gram-negative enterobacteria in the etiology of CFS and for the presence of an increased gut-intestinal permeability. J Affect Disord. 2007 Apr;99(1-3):237-40.

[7] Maes M, Kubera M, Leunis JC, Berk M. Increased IgA and IgM responses against gut commensals in chronic depression: further evidence for increased bacterial translocation or leaky gut. J Affect Disord. 2012 Dec 1;141(1):55-62.

[8] Simrén M, Barbara G, Flint HJ, Spiegel BM, Spiller RC, Vanner S, Verdu EF, Whorwell PJ, Zoetendal EG. Intestinal microbiota in functional bowel disorders: a Rome foundation report. Gut. 2012 Jul 10. PubMed PMID: 22730468.

[9] Zhou Q, Zhang B, Verne GN. Intestinal membrane permeability and hypersensitivity in the irritable bowel syndrome. Pain. 2009 Nov;146(1-2):41-6.

This post originally appeared in 2012 and is updated regularly.