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Leaky Gut Syndrome and IBS

Is Increased Intestinal Permeability the Problem?


Updated July 21, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

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Photo: Steve McAlister/Image Bank/Getty Images

Leaky gut syndrome, also known as increased intestinal permeability, is a condition that has been linked with a variety of health problems, including irritable bowel syndrome (IBS). This overview of leaky gut syndrome/intestinal permeability as it relates to IBS will help you to better understand the condition and to determine if it may be playing a role in your own symptoms.

What Is Leaky Gut Syndrome?

Leaky gut syndrome, more properly known as increased intestinal permeability, refers to a state in the body in which the tight junctions of the epithelial cells that line the digestive tract are damaged and/or altered and therefore do not provide the tight barrier function that they were designed for. When increased permeability is present, it is thought that certain molecular substances are able to permeate through the gut wall barrier triggering an inflammatory immune system response. It is this inflammatory response that is thought to play a role in the various health conditions associated with intestinal permeability.

However, like a chicken and egg problem, it is unknown if the health problem causes the permeability or if the permeability causes the health problem. Other factors have been theorized to cause this damage to the intestinal lining, including:

  • Bacterial or viral infections
  • Certain medications
  • Poor diet

Health Problems Associated with Intestinal Permeability

The following health problems have all been theoretically associated with increased intestinal permeability. In each case, a chronic inflammatory condition caused by the permeability is thought to be carried through the bloodstream to other parts of the body contributing to or causing the health problem. It is important to note that at this point any discussion of a connection between increased intestinal permeability and any of the following health problems is only at the level of a hypothesis, not anywhere near any sort of a firm conclusion.

A Word of Caution

As a psychologist, I must say that I hate the original name "leaky gut" due to the awful imagery that it evokes. We all know that our bodies are very reactive to imagery (give a teenage boy some erotic pictures and see what happens to their bodies!). I have also heard many "leaky gut" experts talk about the syndrome and describe how "chunks of food" enter the bloodstream, causing all sorts of havoc. My concern is that worrying about "how leaky your gut is" is only going to cause unnecessary anxiety, and we all know that anxiety can contribute to unwanted digestive symptoms!

It may be of help to become re-acquainted with basic biology. When we eat food, the process of digestion, or the breaking down of food into its nutritional components, starts immediately. Chewing our food and enzymes from our saliva both contribute to this process. In our stomachs, food is further broken down by pepsin and hydrochloric acid. If you have ever encountered hydrochloric acid in real life, you know that it is very powerful stuff. Therefore, by the time the food you have eaten has made its way to your small and large intestine, it has been pretty much broken down into the level of its micronutrients, not large chunks of food! Granted, sometimes you may see a small bit of undigested food passing its way through your stool, but believe me, a piece that big is certainly not making its way into your bloodstream!

Here is a much more helpful way of looking at what is going on: As of now, research is confirming, that for some individuals, the cells of the intestinal lining are not providing the barrier functioning that they should be, resulting in a state of intestinal permeability. It would appear that some select molecules may be getting through this barrier and perhaps triggering an immune system response that is contributing to or directly causing symptoms and/or disease in other parts of the body.

Research on Permeability and Bowel Disease

Researchers have been looking into the relationship between intestinal permeability and bowel disease. Here is an overview of some of the more relevant findings:

Interestingly in rats, where it is a little easier to look more thoroughly, permeability is more likely to be seen in the small intestine than in the large intestine.

In humans, permeability is measured by having subjects drink a solution that contains "probe molecules", typically mannitol and lactulose. Mannitol is easily absorbed, while lactulose being a larger molecule is less likely to be absorbed. Urine samples are taken at intervals following the ingestion of the solution and a ratio is calculated regarding the presence of lactulose and mannitol. If there are high levels of both molecules, increased permeability is thought to be present.

Studies have found that an increase in small intestine permeability can contribute to the onset of bowel disease, but only if other contributory factors are present. Changing the gut flora with probiotics, antibiotics or other such products can result in either an improvement in disease and/or an improvement in intestinal permeability. In cases where improved permeability is seen it is again unclear which comes first - does the disease improve resulting in the improvement in permeability or does the improved permeability improve the disease.

Increased Intestinal Permeability and IBS

Researchers have been pursuing several different hypotheses relating to a relationship between IBS and increased intestinal permeability. In a review by Camilleri, et. al., the following lines of inquiry are discussed:

  • Post-infectious IBS: It would appear that the initial illness that resulted in the ongoing IBS has a negative impact on gut permeability that persists over time.

  • Genetic predisposition: Research has been focused on identifying genes that are linked with inflammation, permeability and IBS.

  • Stress: Researchers are looking into the role that stress plays in the inflammatory response and subsequent permeability.

Multiple studies have shown increased levels of both small and large intestine permeability in IBS patients regardless of IBS sub-type. In the Camilleri review, it is discussed that increased permeability as well as the role of inflammation in IBS may account for many of the extra-intesinal symptoms experienced by many IBS patients. This may come as a great relief to those of you who have had those symptoms dismissed or minimized in the past.

Increased Intestinal Permeability and Food Intolerance

Some IBS authors have written of a connection between increased intestinal permeability and food intolerance. The theory is that the food particles are breaching the barrier of the intestinal wall triggering a response by the immune system and setting you up for a food intolerance. I was not able to find any research on the subject to either support or negate this hypothesis.

What This Means for You

Although research is beginning to show that increased intestinal permeability may be playing a role in IBS, we are a long way off from having any concrete information about this role and what to do about it. That being said, if you suspect that increased intestinal permeability is contributing to your IBS symptoms, discuss your concerns with your physician.

As research has indicated that a healthy gut flora may help to improve permeability, this article is a good place to start:

Taking probiotics may be helpful:

Some people have found that eating cultured or fermented foods have been beneficial in maintaining optimal gut flora:

If you think that a food allergy, stemming from an increased intestinal permeability state, is contributing to your IBS, the following articles will be of help:


Camilleri, M., et.al.  "Intestinal barrier function in health and gastrointestinal disease" Neurogastroenterology & Motility 2012 24:503–512.

Isolauri, E. "Probiotics in human disease" The American Journal of Clinical Nutrition 2001 73: 1142S-1146S.

Matricon, J., et.al. "Review article: associations between immune activation, intestinal permeability and the irritable bowel syndrome" Alimentary Pharmacology & Therapeutics 2012 36: 1009-1031.

Zhou, Q. "Intestinal Membrane Permeability and Hypersensitivity In the Irritable Bowel Syndrome" Pain 2009 146:41-46.

DISCLAIMER: The information contained on this site is for educational purposes only and should not be used as a substitute for diagnosis or treatment rendered by a licensed physician. It is essential that you discuss with your doctor any symptoms or medical problems that you may be experiencing.

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