Digestion Part 5: Leaky Gut Syndrome

Leaky gut isn’t a specific ailment like Celiac disease or heart disease. A syndrome is a collection of symptoms that usually occur together. Leaky gut syndrome is associated with food sensitivities, IBS, malnourishment/malabsorbtion, and autoimmune diseases. If you experience some or all of these symptoms it may be because the lining of your gut is faulty. I mention leaky gut because it is important to understand this function of the gut in order to understand Celiac disease, gluten intolerance, and the general importance of having a healthy gut.

Leaky gut syndrome is still regarded as a fringe concept by the conventional wisdom. The NHS have a particularly snotty description of “leaky gut syndrome”.

“While it’s true that some conditions and medications can cause a “leaky” gut (what scientists call increased intestinal permeability), there is currently little evidence to support the theory that a porous bowel is the direct cause of any significant, widespread problems.”


I’ll let you decide.


In this post I’ll describe what is meant by having a “leaky gut”. Or more precisely, Dr. Sarah Ballantyne PhD, the “Paleo Mom”, will be doing most of the heavy lifting. I really can’t do much better than her post on leaky gut. If you don’t fancy reading the whole thing, just read the parts in bold.

One of the fundamental principles of paleolithic nutrition is avoiding foods that damage the lining of the gut. Essentially, the gut is just a long, wrinkly tube. Inside this tube, food is digested by enzymes and friendly resident bacteria, breaking down the components of our food to their simplest forms: proteins are broken down into amino acids; carbohydrates are broken down into monosaccharaides; and, fats are broken down into fatty acids. What can’t be digested by our bodies is excreted as waste.”

“Amazingly, a single layer of highly specialized cells (called enterocytes) is all that separates the inside of the tube from the outside. These enterocytes have two very specific jobs:  1) transport the digested nutrients from the “inside-the-gut” side of the cell to the “outside-the-gut” side of the cell; and 2) keep everything else on the inside of the tube.”

“Immediately outside this tube are two important parts of the digestive system: 1) the resident immune cells of the gut whose job it is to protect against pathogens which might accidentally find their way through the enterocytes; and 2) a network of blood vessels and lymphatic vessels that carry the digested nutrients from our food to the tissues in our body that need them”.

A “leaky gut” occurs when either the enterocytes are damaged or the proteins that form the tight bond between these cells and hold them together as a solid layer are damaged (or altered). When this happens, it creates microscopic holes through which some of the contents of the gut can leak out”.

What leaks out isn’t big chunks of food. Instead, it’s a combination of many different pathogens: incompletely digested proteins, bacteria or bacterial fragments from those friendly bacteria that are supposed to stay inside your gut, or a variety of toxic substances or waste products that would normally be excreted. When these pathogens leak out, the resident immune cells of the gut recognize them as foreign invaders and mount a response against them”.

Some pathogenic substances (like bacterial fragments and toxins) cause generalised inflammation by triggering the release of chemicals called inflammatory cytokines (the chemical messengers that circulate in the blood and tell white blood cells to attack). This type of inflammation has no target so any cell in the body can be an innocent victim… This type of inflammation can be a major contributor to health issues ranging from psoriasis and asthma to ADHD and depression.”


Ballentyne goes on to describe specific (as opposed to generalised) inflammation, and how the body creates antibodies to attack specific molecules…

“It is also the formation of these types of antibodies that can cause autoimmune diseases… sometimes the antibodies that form in response to “leaked-out” proteins target a sequence of amino acids that isn’t unique to that protein, but instead is a sequence of amino acids also found in many other normal proteins in the human body. When this happens, the body attacks itself thinking its own cells are foreign invaders.

“For example, an antibody could form against a sequence of amino acids that is found in the insulin-secreting beta cells of the pancreas. When the body attacks those cells, it causes Type I Diabetes. An enormous range of autoimmune diseases can be caused in this way, from lupus to Celiac disease to Graves’ disease (many of which include genetic susceptibility as confounding factor).”


In summary: anything that damages the gut lining can lead to malnourishment, a host of autoimmune diseases, and allergies to otherwise safe foods (chicken, beef, apples etc).