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  • Writer's pictureJoan Rothchild Hardin

The Gut’s Mucosal Lining & Leaky Gut

This is an excerpt from a longer article originally posted on 5/10/2015. For the full article, see INCREASED GUT PERMEABILITY – CAUSES & CONSEQUENCES.

Source: Juice Hugger

Those of you who have been following this blog know I’m interested – for personal reasons and also just because it’s fascinating – in how the state of the probiotics in our gut microbiomes affects our health in general.

So this development is of great interest to me: A different kind of PREbiotic dietary supplement, Good Gut Daily, has recently entered the market. PREbiotics provide the nourishment for our PRObiotics. This kind is polyphenol-based and has  been clinically shown to calm acute digestive symptoms in as little as 30 minutes and enhance immune health. For those of you who, like me, suffer from ongoing digestive health problems and haven’t found a satisfactory solution, the arrival of this new supplement is excellent news.

Polyphenols are naturally occurring compounds found in plants – including fruits, vegetables, tea, coffee, and wine.

I’ve written about Good Gut Daily in more depth in an earlier post but, in the interest of not overwhelming you with information, I thought it useful to do a preliminary post on some of the causes of increased intestinal leakiness so you can see how your GI problems originated and how poor gut health creates major health problems elsewhere in your body.

This post grew out of a phone and email conversations with molecular biologist Rob Wotring, the Founder and CEO at Greenteaspoon. Many thanks, Rob, for sharing some of your wealth of information on how the gut works. (Wotring, 2015).


The human digestive tract runs from the mouth at the top to the anus at the other end. Foreign matter (food) is taken in and partially broken down by chewing in the mouth. It then travels down through the esophagus to the stomach and from there into the small and large intestines, where it is selectively digested. During this trip, various phases of digestion take place  and nutrients are extracted and absorbed. The liver, gall bladder and pancreas, organs that aid in the digestive process, are located along the length of the GI tract.

The total length of the GI tract varies from person to person. In an adult male the range is 20 to 40 feet. On average, the small intestine in adults is 22 feet long and the large intestine is 5 feet.

As you can intuit, a lot could go wrong during that long trip – and much of that depends on the quality of what you deliver to your mouth as ‘food’.


You can see the location of the mucosal layer (called ‘mucous coat’ in the diagram below) and the intestinal villi in this cross section of the human small intestine. The empty space in the center, just below the villi (the spikes you see in the image of a healthy mucosal membrane in the image to the left above),  is called the lumen, the tube in which food travels through the intestines.



Increased gut permeability – also known as hyper-permeable intestines or “leaky gut” – describes the intestinal lining’s having become more porous than it should be so the process of what is allowed out into the body no longer functions properly.  Larger, undigested food molecules and other bad things (such as yeasts, toxins, and other forms of waste  that normally would continue on and get excreted through the anus) flow freely through these too-large holes in the intestinal lining and enter the bloodstream, where they don’t belong and are treated as dangerous invaders.

The  gut’s mucosal layer is thin, delicate – and very important. This is where our probiotic bacteria live, so degrading it also degrades the strength of our immune systems. The probiotics residing in the gut mucosal layer make up 70-90% of the human immune system.

Damage to the gut’s mucosal layer leads to a whole range of serious problems as the body tries to cope with the invaders being released into the bloodstream. Once this lining has become disturbed, allowing problematic things to flow through it into the blood stream, a cycle of chronic irritation begins, leading to chronic inflammation in the body and a whole series of autoimmune conditions. For an easy to understand explanation of increased gut permeability, see Leaky Gut Syndrome in Plain English – and How to Fix It. (Reasoner, undated)

Symptoms associated with Leaky Gut Syndrome (Age Management & Hormone Balance Center, 2013)

  • Abdominal Pain (chronic)

  • Bloating

  • Anaphylactoid Reactions

  • Anxiety

  • Gluten Intolerance (celiac)

  • Heartburn

  • Migraines

  • Multiple Chemical Sensitivities

  • Myofascial Pain

  • Poor Exercise Tolerance

  • Poor Memory

  • Recurrent Vaginal Infections

  •  Brittle Nails

  • Swollen Lymph Glands

  • Constipation

  • Liver Dysfunction

  • Abdominal Spasms

  • Chronic Fatigue

  • Constant Hunger Pains

  • Sluggishness

  • Insomnia

  • Excessive Flatulence

  • Shortness of Breath

  • Fears of unknown origin

  • Hemorrhoids

  • Malnutrition

  • Muscle Cramps

  • Muscle Pain

  • Mood Swings

  • Poor Immunity

  • Recurrent Bladder Infections

  • Recurrent Skin Rashes

  • Hair Loss

  • Food Allergies

  • Diarrhea

  • Brain Fatigue

  • Anal Irritation

  • Depleted Appetite

  • Depression

Here’s a partial list of diseases and conditions associated with increased intestinal permeability (Galland, undated) (Age Management & Hormone Balance Center, 2013):

  • Accelerated Aging

  • Acne

  • AIDS

  • Alcoholism

  • Autism

  • Arthritis

  • Asthma

  • Candidiasis

  • Celiac disease


  • Childhood hyperactivity

  • Chronic arthritis/pain treated with NSAIDS

  • Chronic Fatigue Syndrome

  • Cystic fibrosis

  • Chronic hepatitis

  • Colon Cancer

  • Dermatitis

  • Eczema

  • Environmental illness

  • Fibromyalgia

  • Food Allergies & intolerances

  • Giardia

  • Hepatic dysfunction

  • HIV infection

  • Hives

  • Inflammatory bowel disease & syndrome

  • Infectious enterocolitis

  • Liver Dysfunction

  • Malnutrition

  • Multiple food & chemical sensitivies

  • Multiple sclerosis

  • Neoplasia treated with cytotoxic drugs

  • Pancreatic dysfunction & insufficiency

  • Psoriasis

  • Schizophrenia

  • Spondyloarthropathies

  • Ulcerative Colititis

  • Urticaria

There are other chronic diseases and conditions we now know are also autoimmune in nature – including allergies, diabetes, lupus, multiple sclorosis, myesthenia gravis, endometriosis, some heart conditions, juvenile arthritis, chronic Lyme disease, myasthenia gravis, PANDAS, PCOS, pernicious anemia, Raynaud’s, restless leg syndrome, rheumatic fever, rheumatoid arthritis, some thyroid disease, vitiligo … and many others. Learn more about AUTOIMMUNE DISORDERS.

Twelve years ago the father of integrative medicine, Dr Andrew Weil, offered this definition of leaky gut:

Leaky gut syndrome is not generally recognized by conventional physicians, but evidence is accumulating that it is a real condition that affects the lining of the intestines. The theory is that leaky gut syndrome (also called increased intestinal permeability), is the result of damage to the intestinal lining, making it less able to protect the internal environment as well as to filter needed nutrients and other biological substances. As a consequence, some bacteria and their toxins, incompletely digested proteins and fats, and waste not normally absorbed may “leak” out of the intestines into the blood stream. This triggers an autoimmune reaction, which can lead to gastrointestinal problems such as abdominal bloating, excessive gas and cramps, fatigue, food sensitivities, joint pain, skin rashes, and autoimmunity. The cause of this syndrome may be chronic inflammation, food sensitivity, damage from taking large amounts of nonsteroidal anti-inflammatory drugs (NSAIDS), cytotoxic drugs and radiation or certain antibiotics, excessive alcohol consumption, or compromised immunity.” (Weil, 2005)

Andrew Weil, MD


This thin, moist layer lining of the intestinal walls serves many important functions:

  1. Determines which nutrients pass through the intestinal walls and into the blood stream

  2. Protects and covers mast cells that contain histamines

  3. Activates enzymes

  4. Secretes antibodies made from the intestinal wall to support immune defenses

  5. Prevents yeast and parasites from adhering to the intestinal wall

All of these factors can lead to breakdown of the tight junctions and leaky gut. NSAIDs are pain relievers like Aspirin, Aleve, Advil, etc. SIBO is an acronym for small intestinal bacterial overgrowth. Additionally, low exercise levels is a stressor under the category of physical stress. (Source:


Source: Five Seasons Functional Medicine

See the parent article of this post, Increased Gut Permeability – Causes & Consequences, for further information about the causes listed here:


  • AGE







I recommend going back to the fuller article, Increased Gut Permeability – Causes & Consequences, to read about how these degrade the important mucosal lining that’s home to the good probiotic bacteria in your gut microbiome. This information can preserve or help restore your health.

In my conversation with Rob Wotring  Founder and CEO of Greenteaspoon, which manufactures Goodgut prebiotic supplements, he also mentioned these interesting tidbits about the gut (Wotring, 2015):

  • The gut’s mucosal layer is being created all the time. This may explain why your gut – and the rest of you – can feel awful say in the morning and then good some hours later on in the day.

  • Approximately 40% of your energy goes toward producing the mucus barrier.

  • Women are much more susceptible to disruption of the mucosal layer Progesterone thickens the gut lining.

  • There’s convincing evidence that polyphenol PREbiotics (as in Good Gut Daily) are able to heal damage in the gut lining.

Now that you’ve read about the importance of your intestines and what can happen if their walls become damaged, here’s another depiction of the four layers of the intestinal lining in all its amazing complexity (University of Leeds, undated):


The innermost layer, the MUCOSA, is made up of three parts:

  1.  A thin EPITHELIAL lining which includes glandular tissue

  2.  An underlying layer of loose connective tissue called the LAMINA  PROPRIA which provides vascular support for the epithelium and often contains mucosal glands. Products of digestion pass into  capillaries here. Lymphoid follicles and plasma cells are also often found here.

  3. And finally, next to the lamina propria, the MUSCULARIS MUCOSA, a thin, double layer of smooth muscle responsible for local movement of the mucosa.

The layer next to the mucosa is the SUBMUCOSA, a loose connective tissue layer containing larger blood vessels, lymphatics, and nerves. It can also contain mucous secreting glands.

The layer outside the submucosa is the MUSCULARIS PROPRIA (EXTERNA). There are usually two sub-layers of smooth muscles in the muscularis propria: An inner circular layer and an outer longitudinal layer. The two layers work together to produce peristalsis (rhythmic waves of contraction) to move food through the gut.

The outermost layer is the ADVENTIA (OR SEROSA) consisting of loose connective tissues containing blood vessels, lymphatics, and nerves. This layer is covered by the visceral peritoneum.

And here’s another intestinal cross section so you can see the location of these layers in relation to the central intestinal “tube”, the lumen, where the digesting food is working its way through from the stomach to the anus.


I hope this article will help you understand the importance of keeping – or repairing – your gut microbiome and the mucosal lining that’s its home.

Source: Elissa Goodman


Age Management & Hormone Balance Center. (2013). Gastrointestinal Repair (Leaky Gut Syndrome). See:

Camp, M. (2015). Digestive Health. See:


Hardin, J.R. (12/22/2013, updated 3/9/2014). Autoimmune Disorders. See:

Hardin, J.R. (5/10/2015). Increased Gut Permeability – Causes & Consequences. See:

Hardin, J.R. (5//23/2015. Good Gut Daily – Good News for Your Gut & Overall Health. See:

Reasoner, J. (undated). Leaky Gut Syndrome in Plain English – and How to Fix It. See:

University of Leeds, Faculty of Biological Sciences. Four Layers of the Gastrointestinal Tract. See:

Weil, A. (2005). What is leaky gut? See:

Wotring, R. (2015). Personal communication. © Copyright 2017 Joan Rothchild Hardin. All Rights Reserved.

DISCLAIMER:  Nothing on this site or blog is intended to provide medical advice, diagnosis or treatment.

Comments submitted prior to 8/25/2021

I have suffered with Glossitis for 50 years and this article is right on target. No Drs in the Albany NY area can figure this out . At the present time I have swollen Lymph nodes in several areas they are setting me up for biopsies my blood work fine I know this is my

problem do you know a Dr in this area who would know about this cause.

Marlene Ferri

In reply to Marlene Ferri


If I had glossitis, I would consult a Functional Medicine doc or a Naturopath. This is what I found when I googled ‘Functional Medicine doctors Albany NY’:

As I understand it, glossitis (inflammation of the tongue) can be the result of nutritional deficiencies – eg, of iron, folate, and/or vitamin B12 deficiency. B12 deficiency will also make the tongue sore and beefy-red in color. I found these articles about treating glossitis:

* Everything You Need to Know About Glossitis

* Symptoms Of Glossitis: Causes And How To Treat It Naturally?

I’d also get lymphatic drainage massage for the swollen lymph glands & learn to do it on yourself. (Not advised if you have lymphoma.) And … I’d also make sure I was eating as cleaning as possible (eg, no GMO foods, very little or no refined sugar), getting dental care from a holistic dentist. Some earlier posts on oral health that may interest you:

* Triclosan, Your Toothpaste and Your Endocrine System

* For a Healthy Mouth

* Is Antiseptic Mouthwash Harming Your Heart?

Joan Hardin


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