I found a couple years ago that I am seemingly gluten intolerant. For example during the holidays when I ate alot of wheat containing foods I was a mess for a week or two. I am generally gluten free but maybe once every other month I might have one or two slices of pizza at work when we order pizza. It is usually a crapshoot how I will feel after that. The same applies to when I was on vacation visiting parents and I might have had a small amount of olive bread, for example. I felt generally fine this time.
Is this just a bad idea to do that or would it be considered hormetic to have a small amount every so often?
Kurt Harris has a post directly answering that question: Stress Does Not Imply Hormesis.
Some things, like wheat, probably don't have "mechanisms which where the body's responses leaves you physically 'better off' than before". If wheat is a problem for you, the damaging effects we know about won't be hormetic. Not the cytotoxic T-cell mediated gut response, the cytokines released, the thyroid issues and numerous other inducible auto-immune diseases (especially when intestinal permeability is present), and so on. These are bodily processes produced in an apparent emergency, and they don't appear to make us stronger.
Still, wheat may not be "just a bad idea" either; that depends on the person. Some people probably don't suffer from any of the ill effects of wheat consumption, though this could be the minority and that immunity could be temporary.
It may have been at one point in history, but with present day wheat I would doubt it.
Would be interesting to know if you could build a tolerance by starting with extremely small doses like you can with other toxic substances (e.g. snake venom).