Problems with Wheat

Discoveries in the last 15 years have implicated wheat in a range of autoimmune diseases.  Celiac disease affects a small (but increasing) segment of the population.  This disease is triggered by an allergy to gluten, a specific protein in wheat.  But there are at least two other important antinutrients in wheat that affect everyone, whether or not they are gluten-intollerant. 

The first, and possibly more benign, is WGA (Wheat Germ Agglutenin), a toxic component of wheat that is usually destroyed by cooking.  Importantly, it is much more sensitive to wet heat than dry heat(i.e. baking), which may not be 100% effective in denaturing WGA. This agluttinin, (a type of lectin) can bind to receptors in the small intestine, effectively "gumming them up" and preventing complete absorption of nutrients.  In addition to limiting the nutritional value of meals containing WGA, lectins can also cause gastrointestinal distress or dysbiosis by passing more undigested food to the large intestine, where it is fermented by the microbiota.

The second, and more worrisome component of wheat, is gliadin.  Sometimes referred to as a type of or component of gluten, in 2000 gliadin was found to mimic the ability of cholera toxin to open the tight junctions between intestinal epithelial cells.  By activating the "zonulin" receptor, gliadin (and cholera toxin) make the gut permeable to large particles of food, which enter the body undigested.  Until the early 1980's it was believed that the human digestive system was impermeable to larger particles of food and that only food that was completely broken down into its amino acid, sugar, and lipid components could be absorbed by the body.  This is mostly true, but gliadin can short-circuit the natural process.

Source: Fasano A. Zonulin and Its Regulation of Intestinal Barrier Function: The Biological Door to Inflammation, Autoimmunity, and Cancer. Physiological Reviews. 2011

The outcome of increased intestinal permeability is immune exposure to the entire gamut of ingested substances.  The resulting inflammatory response binds and removes the transgressive food particles, but not before 1) increasing systemic inflammation, and 2) teaching the immune system to recognize and react to a very large array of compounds ... some of which may look like compounds in the human body. 

Therefore, ingestion of wheat sets up the necessary and sufficient conditions for the generation of autoimmunity.

Sources:

Pusztai A, Ewen SWB, Grant G, Brown DS, Stewart JC, Peumans WJ, Van Damme EJM, Bardocz S. Antinutritive effects of wheat-germ agglutinin and other N-acetylglucosamine-specific lectins. British Journal of Nutrition. 1993 July;70(01):313–321.

Fasano A. Leaky Gut and Autoimmune Diseases. Clinical Reviews in Allergy & Immunology. 2012 February 1;42(1):71–78.

Fasano A. Zonulin and Its Regulation of Intestinal Barrier Function: The Biological Door to Inflammation, Autoimmunity, and Cancer. Physiological Reviews. 2011 January 1;91(1):151–175.

Drago S, El Asmar R, Di Pierro M, Grazia Clemente M, Tripathi A, Sapone A, Thakar M, Iacono G, Carroccio A, D’Agate C, et al. Gliadin, zonulin and gut permeability: Effects on celiac and non-celiac intestinal mucosa and intestinal cell lines. Scandinavian Journal of Gastroenterology. 2006 April;41(4):408–419.

Further Reading:

Gluten Freedom: The Nation's Leading Expert Offers the Essential Guide to a Healthy, Gluten-Free Lifestyle Hardcover – April 29, 2014
by Alessio Fasano and Susie Flaherty

Wheat Belly: Lose the Wheat, Lose the Weight, and Find Your Path Back to Health Paperback – June 3, 2014
by William Davis

The Wahls Protocol: How I Beat Progressive MS Using Paleo Principles and Functional Medicine Hardcover – March 13, 2014
by Terry Wahls M.D. and Eve Adamson