"This whole gluten intolerance thing is just a Western upper middle class fad. People are just orthorexic. Why would gluten intolerance increase all the sudden?"
Well, actually it's not a Western upper middle class fad. People in poor countries can be celiac, but they just die and people think it's from something else. When you are a refugee wasting away from chronic diarrhea, that's not so abnormal unfortunately. When you are in Central Illinois and suffering from the same, it is abnormal and you see a doctor and hopefully get a diagnosis.
Why is gluten-intolerance increasing? Doctors are more aware than ever of this condition and are doing more tests. More tests = more diagnosis. Symptoms that were dismissed as "IBS" or one of many other made-up symptom cluster illnesses are being re-diagnosed as gluten intolerance.
So what's the population with the highest level of celiac disease? Preschoolers on the Upper East Side? Nope, the Saharawi, an Arab-Berber refugee population. And maybe they aren't the highest since they were just unlucky enough to be refugees served by doctors interested in celiac research. Testing found that 5.6% of them have celiac. Unfortunately processed wheat flour is their staple food (I wonder when that started?). Before celiac was diagnosed, people thought their children were merely dying from a malnourishing diet or GI illness. Researchers are now finding celiac hotspots across the Middle East, India, and Africa.
This is interesting because so much government food aid contains gluten. How many of the children you see on those "save the children" campaign ads are really suffering from celiac like this child?? How many such starving children will be given gluten-containing food aid and will die as a result?
Another major question is why celiac disease incidence is so high in the region that gave birth to agriculture? The theory that CD was higher in populations that have adopted agriculture more recently like the Irish or the Finnish has not survived now that other populations have been examined more closely. The Finnish and Irish have high levels of CD because they have high DIAGNOSIS levels. Finnish children are tested at birth.