So, "gluten sensitivity" ("allergy"; all allergies are invented conditions to cover up for some form of poisoning) is most likely due to "fortification" and, one must not forget, pesticidal residues.
Notice that municipal water is now most likely chloraminated, because the hundred-year-old water pipes allow for all kinds of contamination to get into the water. Chloramine is a hundred times more toxic than chlorine, and it can be removed only by carbon filtering (chlorine leaves the water if you let the water sit for a few days).
Modified proteins seem to be a major problem, causing "autoimmune conditions" while synthetizing body tissues, and most recently, peptic ulcers. I have collected 13 major causes, and they can converge anytime: