The official definition of Leaky Gut Syndrome is an increase in permeability of the intestinal mucosa to luminal macromolecules, antigens, and toxins associated with inflammatory degenerative and/ or atrophic mucosa or lining. Put more simply, large spaces develop between the cells of the gut wall allowing bacteria, toxins and food to leak into the bloodstream.

70% of our immune system is located around the digestive system.[1] In a normal healthy person the small intestine behaves like a selective sieve allowing only the breakdown products of digestion into the bloodstream. [2] Nutrients and well digested fats, proteins and starches are readily able to enter into the bloodstream whilst large molecules, microbes and toxins are kept out. [3]

In the intestinal tract, villi (finger like projections off the lining the intestinal tract with hair like cell membrane extensions called microvilli), serve as a point of absorption of nutrients. Nutrients such as glucose, amino acids or electrolytes are carried through the microvilli into the cells of the villus via active transport (carrier molecules take the nutrients across the cell membrane).

Leaky Gut Syndrome causes the intestinal lining to become inflamed and the microvilli become damaged or altered. The damaged microvilli cannot then produce the necessary enzymes and secretions that are essential for a healthy digestion and the absorption of nutrients. [4]

In between cells reside desmosomes. These adhere adjacent cells together to form a strong, sturdy structure, which prevents large molecules from passing through. When an area becomes inflamed this weakens the structure of the desmosomes and larger molecules can escape through. This provokes the immune system to produce antibodies (a protein utilised by the immune system to locate and attack foreign objects) to fight off the molecules, as they are perceived as antigens (substances capable of triggering the production of antibodies).

A healthy individual would have a strong enough immune system to control the leakage of toxic substances but as it becomes over loaded the toxins leak into the liver resulting in an overworked overburdened liver. [5]

The Liver

The liver is the largest gland in the body and plays a really important part in detoxification as well as having many other functions including: producing bile, containing bile acids, which aid digestion, filtering out toxins, such as drugs, alcohol and environmental toxins, storing glucose as glycogen, then breaking it down about 4 hours after a meal to be converted to glucose to regulate blood sugar levels, converting ammonia to urea and removing damaged red blood cells.

Leaky Gut completely overworks the liver because it floods it with additional toxins diminishing the liver's ability to neutralise chemical substances. When it cannot cope with the level of toxins the liver expels them back into the bloodstream. The circulatory system then pushes the toxins into the connective tissues and muscles where the body stores them to prevent major organ damage. The liver doesn't get the time to go back and rid the body of the toxins.

As the intestinal lining becomes more and more damaged substances larger than particle size such as disease causing bacteria and fungus, potentially toxic molecules and undigested food particles pass through the weakened cell membranes. These enter the bloodstream, triggering antibodies and cytokines (protein molecules released by the immune system to cause a reaction in other cells) to fight the antigens. The cytokines alert the lymphocytes (white blood cells) to fight the particles that have escaped through the intestinal lining. Toxic oxidants are produced as a result causing allergic reactions and more inflammation throughout the body.

The digestive tract is normally coated with a mucus layer, which keeps out foreign substances. Leaky Gut Syndrome develops as the mucus layer is weakened and the bacteria, which usually resides in the intestine starts to inhabit other parts of the body as well (bacterial translocation), due to the intestinal permeability.

So put very simply your intestine develops leakages allowing substances that would normally be digested to enter the bloodstream. These toxins are passed onto the liver to deal with but it cannot cope with the overwhelming toxins and stores them in the body tissues to come back to later on. The liver is too overworked to go back to the toxins and as the intestinal lining gets consistently weaker more and more toxins and undigested food enter into the bloodstream. The immune system sends out antibodies to fight these foreign substances and in doing that toxic oxidants are produced which attack the body tissues causing allergic reactions and pain and inflammation throughout the body.

[1] Spaeth G, Berg RD, Specian RD, Deitch EA, August 1990, "Food Without Fiber promotes bacterial translocation from the gut" Surgery 108 (2) pp 204-47
[2] Sharma R, 2005, Leaky Gut Syndrome, article.
[3] Lipski E Leaky Gut Syndrome, 1998, "What to do about a health threat that can cause arthritis, allergies and a host of other illnesses" p10 Keats
[4] Gilbere G, 2001, I Was Poisoned By My Body...I Have A Gut Feeling You Could Be, Too, p10, Lucky Press.
[5] Gilbere G, 2001, I Was Poisoned By My Body...I Have A Gut Feeling You Could Be, Too, p11, Lucky Press.