What Happens to the Body with Leaky Gut Syndrome?
Leaky gut syndrome has been discussed in a previous article [link to article] and basically refers to disrupted intestinal permeability that is not only a symptom of gastrointestinal disease but an underlying cause that develops independently. Everyone’s guts are semi-permeable. The mucous lining of our intestines is designed to absorb water and nutrients from our food into our bloodstream. But some people have increased intestinal permeability or hyperpermeability, thus the term “leaky”. That means their guts let more than water and nutrients through. If your intestinal barrier is impaired and the permeability increases, it may be letting toxins and potentially bacteria into your bloodstream. These toxins may trigger an inflammatory response that may manifest as various diseases.
This theory has some appeal as a way of explaining various conditions that we haven’t been able to fully explain yet. However, there is still a significant lack of direct evidence to support it. We do know that the condition of having increased intestinal permeability, or a “leaky gut,” is real. Nevertheless, we don’t know that it’s a disease in and of itself or that it is a symptom or cause of other diseases. Furthermore, it is not currently a recognized medical diagnosis.
What are Potential Causes a Leaky Gut?
Our intestinal lining covers more than 4,000 square feet of surface area inside our abdomen. When working properly, it forms a tight barrier that controls what gets absorbed into the bloodstream. An unhealthy gut lining may have gaps or holes, allowing partially digested food, toxins, and bacteria to penetrate the tissues beneath it . This may trigger inflammation and changes in the gut microbiome (normal bacteria) that could lead to problems within the digestive tract and even other tissues/organs. There are studies showing that modifications in the intestinal bacteria and inflammation may play a role in the development of several common chronic diseases .
We all have some degree of leaky gut, as this barrier is not completely impenetrable and that is by design. Some of us may have a genetic predisposition and may be more sensitive to changes in the digestive system. However, our DNA is not the only one to blame. The known causes of increased intestinal permeability also involve systematic erosion of the intestinal lining. This is not a simple feat. Your intestinal lining has many layers of defense. And while it can be injured temporarily, it is designed to constantly repair and replenish itself. To wear it down enough to penetrate the lining requires a significant assault. Just normal living in modern times may actually be the main driver of this by triggering gut inflammation.
There is emerging evidence that the standard American diet, which is low in fiber and high in sugar and saturated fats, may initiate this process. In addition, other persistent assaults on our gut like chronic disease, chronic stress, chronic drug use or alcohol abuse or radiation therapy are also potential causes.
Other Diseases Associated with Leaky Gut
We already know that increased intestinal permeability plays a role in certain gastrointestinal conditions such as celiac disease, Crohn’s disease, and irritable bowel syndrome (IBD). In these cases, scientists generally consider it to be a symptom, not a cause. These diseases cause chronic inflammation in the intestines, which leads to erosion of the intestinal barrier gradually over time. Many other diseases elsewhere in the body have been suggested as possible consequences of leaky gut syndrome. The idea is that “toxins” from your intestines may leak into your bloodstream and cause an inflammatory response. Some studies show that leaky gut may be associated with other autoimmune diseases (lupus, type 1 diabetes, multiple sclerosis), chronic fatigue syndrome, fibromyalgia, arthritis, allergies, asthma, acne, obesity, and even mental illness . However, this has not yet been backed by confirmed scientific evidence.
There is also some evidence of higher levels of gut bacteria products in the blood of people with gastrointestinal (GI) diseases that are known to cause intestinal permeability. In these cases, inflammation is primarily from other causes, though bacterial products could make it worse. Scientists have also measured increased GI bacterial permeability in liver disease, which is directly related to the gut. Bacteria products traveling from the gut to the liver via the portal vein could contribute to liver disease but is not necessarily the cause of it [1,2].
Potential Affects of Leaky Gut on the Body?
Erosion of your intestinal lining is one thing, and intestinal permeability is another. Most people who think they may have a leaky gut have certain common gastrointestinal symptoms, such as abdominal pain, food sensitivities, bloating and indigestion. These types of symptoms are common and may have many possible explanations, and many of them may injure your intestinal lining. You don’t have to have a leaky gut to experience those effects.
Chemical irritants, abrasive particles, or bacteria inside your gut will eventually erode your gut lining if it is under constant assault.This is what happens in peptic ulcer disease and SIBO (small intestinal bacterial overgrowth). The wrong kind of bacteria overwhelms the other bacteria that would usually balance them. The erosive acids and enzymes in your gut overwhelm the protective mucus that usually neutralizes them.
Erosion of your gut lining will affect your digestion, your immunity, and your sensitivity to pain in your intestines. And in some cases, it may lead to intestinal permeability. But it doesn’t have to go that far for you to feel unwell. If you have gastrointestinal symptoms, these are likely related to the underlying condition that would be injuring your intestinal lining in the first place. Many gastrointestinal diseases share these same symptoms.
It is difficult to separate symptoms of intestinal permeability from the inflammation that precedes it, but some people do have increased intestinal permeability. A large variety of gut barrier disruptors and/or gut microbiota disturbers may potentially result in increased bacterial permeability and subsequent inflammation locally and systemically. These include diet, infections, and alcohol consumption .
- Nutrients and food ingredients have been reported to contribute to the maintenance or alterations of gut microbiota and the intestinal barrier function 
- Numerous studies have shown chronic alcohol consumption is responsible for intestinal barrier dysfunction as well as alterations on both the quality and quantity of gut microbiota .
- Infections can play a role in regulating the mucosal barrier. A good example is Helicobacter pylori, a Gram-negative bacterium infecting the human stomach .
When your gut lining is more permeable, bacteria living in your gut could cross the intestinal barrier, but we don’t know if this does significant harm separate from the original disease or injury that caused it.
-  Camilleri M. (2019) Leaky gut: mechanisms, measurement and clinical implications in humans. Gut. 68(8):1516-1526. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6790068/
-  Vanuytsel T, Tack J, Farre R. (2021) The Role of Intestinal Permeability in Gastrointestinal Disorders and Current Methods of Evaluation. Front Nutr.;8:717925. Published 2021 Aug 26. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8427160/
-  Mu Q, Kirby J, Reilly CM and Luo XM (2017) Leaky Gut As a Danger Signal for Autoimmune Diseases. Front. Immunol. 8:598. https://www.frontiersin.org/articles/10.3389/fimmu.2017.00598/full
-  Suzuki T. (2013) Regulation of intestinal epithelial permeability by tight junctions. Cell Mol Life Sci; 70(4):631–59. doi:10.1007/s00018-012-1070-x
-  Yu QH, Yang Q. (2009) Diversity of tight junctions (TJs) between gastrointestinal epithelial cells and their function in maintaining the mucosal barrier. Cell Biol Int; 33(1):78–82. doi:10.1016/j.cellbi.2008.09.007