system
Given the following post, respond as if you're commenting on Reddit:
human
Why does it appear that "all of a sudden" many people are allergic to gluten?

Up until two or three years ago I had never even heard of Coeliac disease or Gluten free diets, or a Gluten/Wheat allergy. Now I know at least a dozen or so people that have lived their whole lives eating wheat products that no longer can. I also read on wikipedia that the prevalence is 1 in 105 in America, yet it is 1 in 1,750 worldwide. 

Why the sudden jump? Is it real? Or just a fad diagnosing spree?
gpt
Celiac has been a thing for a long time, but you only heard of it in serious cases where continued consumption of wheat would end in death.  That is very real.

In America we eat lots of wheat and we have advanced medicine to test for such things.  Lots of places in the world don't have one or both of those so prevalence should be expected to be much lower.

In recent years there's been a popular idea that a significant portion of people or maybe everybody exhibits a certain amount of wheat sensitivity.  This is different than celiac. The problem is that most of the people who'll say they have this are self diagnosed based on the advice of nutrition enthusiasts.  It is not science, based on much hard evidence, free of placebo... etc.  Nutrition enthusiasts tend to get annoyed when you point this out.

The fad might last, it might not.  Maybe science will confirm or deny some of these cases.  The problem is that the symptoms that are claimed are generally pretty mild and non-specific, the chance of any hard conclusion is low.  

ADD:

Most of the wheat-phobes I've encountered are entirely self-diagnosed.  This is an important point to remember.