There is no shortage of information on the internet about “Leaky Gut” and “Leaky Gut Syndrome”. For instance:

“4 steps to heal Leaky Gut”

“9 signs you have a leaky gut”

“Leaky Gut foods to avoid”

“Could Leaky Gut be what is troubling you?”

“Leaky Gut: Can this be destroying your health?

“How to live with and identify Leaky Gut Syndrome”

Is this really a thing?

It seems there are as many skeptics about “Leaky Gut” as there are people promoting it. When I ask audiences at my seminars “Who has heard of leaky gut syndrome?”, everyone, EVERYONE, raises their hand. When I ask “Who thinks the medical establishment takes it seriously?”, no one raises their hand, ever.

This is unfortunate, because Leaky Gut is a thing, and can cause serious problems for some people. It may also contribute to other conditions not normally thought of as being related to gut problems.

In the basic science world, “leaky gut” is called “increased intestinal permeability”, and it is a big thing. Increased intestinal permeability is a major factor in Inflammatory Bowel Diseases (such as Crohn’s Disease) and Celiac Disease, and may contribute to non-alcoholic fatty liver disease, diabetes, asthma, autism, schizophrenia, and autoimmune disease. It may also contribute to feelings of chronic fatigue, and mood disorders. How?

It helps to understand a little about the gut, and the “gut barrier”. The lining of our gut consists of a single layer of cells, that provides a barrier between us and the outside world. Yes, the outside world!

My Psychology Graduate Advisor, Don Novin, used to say that “We are all just donuts”, with an outside, and an inside, and an outside inside.

The barrier on our outside-outside is skin, which is tough and keeps pretty much everything out. But the barrier of our inside-outside has to be able to let in some things, like nutrients, but keep other things, like toxins and pathogens, out. This is a huge challenge.

The permeability of the barrier has to be carefully regulated. The cells that make up the barrier have to be far enough apart to allow food to be absorbed, but not so far apart that other things get in. There are proteins on the cells (such as ZO-1 and occludin) that help keep the cells close together, and the gut’s immune system also helps. If there is a problem with this regulation, the cells get too far apart and you get “leaky gut”, aka “increased intestinal permeability”.

So, what can mess up gut barrier regulation?

Some people have genetic traits that seem to lead to an exaggerated inflammatory response to microbes in the gut. These gene variants have been associated with Inflammatory Bowel Disease. If the response to microbes is inappropriate, the gut barrier becomes more permeable, and so do the blood vessels in the vicinity, leading to swelling, pain, and bleeding. The increased permeability can allow more pathogens across the barrier, increasing inflammation even more. This makes the disease worse, and can be life-threatening.

In the case of celiac disease, an allergy to gluten (found in many grains) also induces inflammation. This leads to malabsortion of nutrients, malnutrition, and damage to the gut. Other types of food allergies and sensitivities are related to unruly gut immune responses, and also lead to increased permeability. So, keeping the gut’s immune system regulated and happy is a key ingredient in a healthy gut barrier.

How do we keep our gut immune system happy?

Eating a healthy, varied diet is a big help. Eating probiotic foods may also help, because one thing that tends to upset the gut immune system is a condition called “dysbiosis”. Research into our little friends, the gut microbes, is showing that there are many different types of them, and they need to be in balance. Dysbiosis is when the populations you have are not diverse enough, and some of them do not play nice with the gut barrier. So, the barrier can become leaky and inflamed. There is some evidence that probiotics can improve gut barrier function, presumably by encouraging the gut bugs to play nice (more on this in a future blog).

One of the most important things we can do to maintain a healthy gut barrier is managing chronic stress. Chronic stress dysregulates the immune system, and impairs the expression of the barrier proteins between the cells lining the gut (epithelial cells). Not only that, but stress hormones (catecholamines: epinephrine and norepinephrine) from us can act on unruly bacteria to make them more aggressive, and probably contribute to dysbiosis. Dysbiosis also can activate gut-brain connections that can lead to mood disorders such as anxiety.

So, yes. Leaky Gut (aka increased intestinal permeability) is a thing! I suspect some of the skepticism derives from the name. “Leaky Gut” doesn’t sound very scientific, even if it is pretty descriptive. But “increased intestinal permeability” is a mouthful, so I suspect the term “Leaky Gut” will stick around.