Gluten is one of the proteins found in wheat (durum, emmer, spelt, farina, faro, KAMUT ®, Khorasan wheat, and einkorn) as well as rye, barley and triticale.   Gluten is commonly found in breads, baked good, sauces, salad dressings, cereal, pasta, soups and sauces.  Barley is commonly used in malt, food coloring and beer as well.

Gluten has been around for only about 10,000 years.  Its use in food dates back to the Industrial Revolution where it was used as a type of food glue to help foods maintain their shape.  Because gluten was not part of our evolutionary diet, our bodies are not equipped with the proper enzymes to fully digest this protein.  There are no nutritional benefits derived from eating gluten.  In addition, though the quality of the gluten in our foods has not changed significantly over the past few centuries, the quantity found in foods has increased significantly.

Approximately 70-80% of the population are able to tolerate gluten with no problem.  Because we all lack the enzymes to fully digest gluten, gluten is only partially broken down by the GI tract.  According to studies done by Dr. Alessio Fasano, the head of the Department of Pediatric Gastroenterology and Nutrition at Mass General Hospital for Children, the undigested fragments of gluten and gliadin cause transient intestinal inflammation and can release a molecule called zonulin.

Zonulin causes an opening in the barrier of the GI tract.    Essentially the spaces between the cells lining the gut wall open up and allow foods and other toxins to cross into the blood stream, which would not normally get through.  In 70-80% of the population this is not a problem because the immune system works properly and can remove any offending bacteria, toxins, etc.

The immune system is remarkably complex, however essentially it is composed of two branches.  The innate and adaptive immune system.  The innate immune system is the first line of defense in the GI tract.  The innate immune system is immediate and is not very specific. It will release molecules that destroy or eliminate anything it thinks is foreign.  For example, when the innate immune system is exposed to gluten and gliadin fragments, cytokines (small proteins released by cells that are important in cell signaling and can affect the behavior of other cells) are released in an attempt to breakdown these gluten and gliadin fragments.  Cytokines can induce an attack on the gluten, but can also cause a local inflammation in any tissues nearby.  This can cause very microscopic damage to the gut wall which is not always seen on biopsy because repair occurs fairly quickly.

If the innate immune system is unable to handle the “foreign invader”, then the adaptive immune system takes over.  This branch of the immune system is much more specific, sophisticated and takes more time.  The adaptive immune response can lead to either an antibody-mediated attack or to a cell-mediated attack.

In the case of the antibody-mediated the body customizes antibodies to attack the gluten and gliadin protein fragments.    Occasionally, the immune system malfunctions and the antibodies customized to attack the gluten and gliadin can cross-react or get activated by cells in our body.  When this happens, in addition to destroying the gluten fragments, these antibodies also destroy important tissues in our bodies. Depending on which tissue is being attacked will determine a person’s symptoms.  For example, if the antibodies cross-react with joint tissue, a person can develop arthritis.

According to Dr. Fasano, there are three scenarios which could occur when you eat gluten.

• The gluten is eaten and partially digested. The undigested gluten causes the release of zonulin which opens up the spaces between the gut lining and these protein fragment breach the intestinal barrier.  The innate immune cells respond appropriately and eliminate the fragments and the tiny amount of local inflammation is repaired quickly and the person has no consequences from eating gluten.
• A person eats gluten and the partially digested fragments activate the immune system as above. However, the innate immune system is unable to eliminate the protein fragments and the adaptive immune system gets activated.  There is a miscommunication between the two branches of the immune system.   The adaptive immune system builds antibodies (or cells) to attack the gluten and gliadin fragments which cross-react with the cells found in the intestinal tract.  The immune cells stay locally in the gut and inflammation persists.  In this scenario the person will develop celiac disease.
• The third possibility is that the scenario 2 occurs, except that instead of the antibodies (or cells) staying the in the gut and cross-reacting with tissues in the GI tract, the antibodies and/or activated cells travel throughout the body and cross react with different body tissues. In this case, there will be minimal damage in the GI tract, but the personal will have chronic inflammation elsewhere in the body.  Depending on the tissues which cross-react with the antibodies or activated cells, will determine the person’s symptoms.   This scenario is termed non-celiac gluten sensitivity.

Non-celiac gluten sensitivity can cause multiple symptoms.    Symptoms can often be vague, such as abdominal pain, headaches, foggy mind, chronic fatigue, and depression.

People can live for years without any issues with gluten intolerance.  However, it appears that a change in gut flora (as was addressed last week) can be one of the inciting event which can activate gluten intolerance.   There are no nutritional benefits from ingesting gluten, in addition, it causes inflammation in the gut and the release of zonulin leading to increased intestinal permeability.  Interestingly, it appears that zonulin also causes an increase in permeability of the blood brain barrier and may be associated with inflammatory disorders of the brain.