ELI5 Gluten - why does it seem everyone's intolerant now?

Humanity has lived off bread for thousands of years, so why has the past decade seen such a rise in people 'allergic' to gluten? What is gluten intolerance? What is Celiac’s disease? Why did doctors once think that a banana diet was its cure? Finally, are there any negative effects from a gluten-free diet?   ... We explain like i'm five!     Thank you to the r/explainlikeimfive community, and specifically the following reddit users whose questions and responses formed the basis of this conversation: addacus117, p3tunia, the1ine, police-ical, pupperpowell, pantstoespantstoes & nohissyfits NPR article referenced To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Send us an e-mail: [email protected]