We had lots of kids with food allergies when I was a kid, in Pakistan in the 1970s.
It was just not considered a PUBLIC issue. If you were very allergic to peanuts or shellfish, you’d be very careful about going where people were eating, processing or storing those. For example, my brother who had a seafood allergy would be left home with the ayah (nanny) when we went to Chinese restaurants (they were the only ones to serve shellfish). He didn’t come with us to the harbor because there’d be fisherman unloading crabs and shrimp everywhere.
We didn’t have a lot of packaged foods with a dozen ingredients. So everything at home or at our friends and relatives was easy to verify ingredients.
Can’t imagine what people did with gluten issues. Wheat flour products were EVERYWHERE.
Wheat flour products in many areas were the basis of the diet. Give us this day our daily bread. I expect people with serious gluten issues just didn’t survive, in those parts of the world – it would have been put down to some form of failure to thrive, or death from indigestion. People with less serious gluten issues probably just weren’t really healthy.
I’m not entirely sure there’s not something a little different about the wheat – modern wheat isn’t genetically exactly the same as ancient wheat, though I don’t know whether it affects the gluten. I also don’t know whether gluten issues have anything to do with gut microbiome, which is probably a good deal different in most people on a modern Western diet than it was in people even in the same countries even in the 1950’s.
But I also wonder whether some of the allergy and gluten problems have to do with mixing up people more from different parts of the world, so that people genetically adapted to one sort of diet wind up living where other foods are commonly used. That’s certainly at least a large part of what’s going on with lactose intolerance; which is another thing I never heard of in childhood. But everyone in my grade school had significant, and in most cases near-total, European ancestry.