Antinutrients in Wheat

Grains don't want to be eaten.  As Dr. George Diggs makes clear in his youtube video, plants protect their leaves from herbivores and their seeds from seed-eaters with a whole range of chemical defenses.  In the case of seeds like wheat, there are multiple lines of defense, any one of which should give a thoughtful eater pause.  In combination, these defenses indicate that wheat should not be eaten by humans.

This is a much stronger argument than saying that some humans are gluten-intolerant or gluten-sensitive.  While gluten can be hard to digest for some people and has been identified as the causative agent in Celiac Disease, it is only one of an array of antinutrient compounds found in wheat.

Source: Scientific American, Surprises from Celiac Disease

• Wheat Germ Agglutinin (WGA) binds to cells in the intestine and can cause the gut to leak and create inflammation in the immune system.1,2,3,5
• Wheat Amylase Trypsin Inhibitors may fuel inflammation and immune reactions. 4
• Gliadin, a compound that specifically increases intestinal permeability, an idea first popularized as "leaky gut syndrome".6,7,8

Caveats: not all of these compounds are harmful to everyone, preparation (e.g. cooking) can destroy some toxins like WGA, and 'the dose makes the poison', so low doses of these antinutrients should have less effect than large doses.  But the fact remains that wheat is not a perfect food.  It increases inflammation, and in susceptible individuals provides the necessary and sufficient conditions for developoing autoimmunity, arthritis, diabetes, etc.

Gliadin is particularly worrisome because of its ability to 'tear holes in the gut'.  Gliadin (a component of gluten) mimics cholera toxins that can unlock the tight junctions sealing intestinal cells to one another.  Without intact junctions between the cells, open holes in the gut lining open are large enough to allow undigested food into the body.  These chunks of food have been detected using genetic testing and observed in animal studies (cite paper found WGA bound to everything).

Source: Scientific American, Surprises from Celiac Disease

This is not just a problem for people with Celiac's disease or gluten sensitivity. Wheat's gliadens have the same effect in everyone; they increase inflammation load (your body has to clean up everything that spilled into your blood after you ate wheat), and they provide the exposure of your immune system to foreign compounds which may trigger autoimmune conditions such as M.S., arthritis, diabetes, etc.  This topic is discussed in depth in this interview with Dr. Alessio Fasano, the researcher who discovered how wheat mimics cholera toxins to break down intestinal epithelium.

Sources
1.van Buul, V. J. & Brouns, F. J. P. H. Health effects of wheat lectins: A review. Journal of Cereal Science 59, 112–117 (2014).
2.Catassi, C. et al. Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders. Nutrients 5, 3839–3853 (2013).
3.Sollid, L. M. & Jabri, B. Triggers and drivers of autoimmunity: lessons from coeliac disease. Nat Rev Immunol 13, 294–302 (2013).
4.de Punder, K. & Pruimboom, L. The Dietary Intake of Wheat and other Cereal Grains and Their Role in Inflammation. Nutrients 5, 771–787 (2013).
5.Junker, Y. et al. Wheat amylase trypsin inhibitors drive intestinal inflammation via activation of toll-like receptor 4. J Exp Med 209, 2395–2408 (2012).
6.Pellegrina, C. D. et al. Effects of wheat germ agglutinin on human gastrointestinal epithelium: Insights from an experimental model of immune/epithelial cell interaction. Toxicology and Applied Pharmacology 237, 146–153 (2009).
7.Pusztai, A. et al. Antinutritive effects of wheat-germ agglutinin and other N-acetylglucosamine-specific lectins. British Journal of Nutrition 70, 313–321 (1993).
8. Fasano, Alessio, et al. "Zonulin, a newly discovered modulator of intestinal permeability, and its expression in coeliac disease." The Lancet 355.9214 (2000): 1518-1519.