I want to address what Dr. William Davis gets wrong, and what he gets right, and then explore some mechanisms that should add to the discussion here.
First of all, Dr. William Davis is not my preferred ambassador to deprogram the masses about their wheat addiction - he seems to completely miss the fact that gliadin IS wheat gluten, and makes several statements that are just plain wrong (like gliadin being a recent addition to wheat).
If you want a scientifically-based presentation on gluten, gliadin and wheat, look at the video here: http://bozemanchiropractic.com/bozeman-chiropractor/index.php/news/the-real-truth-of-wheat-gluten-intolerance-and-celiac-disease/
That video is by Dr. Peter Osborne, who is my preferred ambassador on this subject. Definitely worth a watch.
What Dr. Williams gets right is that wheat is a dangerous food. Is that due to peptides that trigger an opiate-like response? I don’t really know. I suspect that developing antibodies to the prolamine that also attack your opiate receptors are a bigger problem.
I know from the scientific literature that wheat that spikes your blood sugar worse than sugar, and that it raises your insulin levels. I also know that wheat has been scientifically linked to autoimmune diseases, a wide variety of inflammatory disorders, as well as mental disorders like schizophrenia and depression. This is incontrovertible.
So what are the mechanisms that explain this?
For one, consider that there are opiate receptors in all sorts of tissues, not the just the brain. White bloods cells for instance have receptors for every “molecule of emotion” known. This is how your emotional state effects your immune state.
Second, these prickly and hard-to-digest proteins leak across damaged small intestine, creating an acquired immune response to those peptides. That immune response create antibodies that can attack body tissues that have the same present protein sequences, and inflammatory cascades that can deposit in various tissues creating inflammation. It may not even take a damaged gut to pass longer peptides. I’ve been reading Gut for years, and the intestines seem to be more permeable than the textbooks have told us. Typically 60% or more the of WBCs are hanging out by the gut.
Third, there are non blood-based pathways that go directly from the gut to the brain. I’m speaking of Cranial Nerve 12 here. These neural pathways may provide transport for peptides to get into the brain without having to cross the blood-brain barrier.
Fourth, keep in mind for the last ten years or so they have been saying 95% of the serotonin in the body is in the gut. Think about it. Just gut damage alone could cause depression. Makes one wonder if the SSRIs can damage the gut as well.
A final thought:
Wheat may only be damaging to some people, or it may just be bad food for everyone. Just because we have been eating it for ten thousand years does not mean that it is healthy. A food can give you calories to keep you alive and still cause chronic disease, which can take 40 years to develop.