Earlier quoted context omitted.
> A person in the middle ages wouldn't be surrounded by a toxic environment Are you serious? You don't think living in a tiny room with 10 family members and all kinds of animals (along with all of the lice, fleas, diseases, etc. that go along), with a wood fire filling the whole place with eye-stinging, lung-choking smoke, was a "toxic environment"? You'd be eating mostly grains, with very occasionally some meat, an…
I guess the difference here is that you are assuming they are drinking excrement filled water, where I was thinking they are drinking fresh water. There is probably a large difference between those that began to live in more crowded cities and those that were still in more pristine country side. It is not clear cut whether people were smaller in the middle ages. http://researchnews.osu.edu/archive/medimen.htm Bathing…
This is just a simple example of how bathing/changing clothes can affect your health. In the middle ages, you would have been walking in pathogen soup in all those dirty, sweat/urine/etc laden clothes you couldn't change out of.
Don't discount the impact of simple cleanliness. Pristine countryside? Doesn't exist. Go travel to one of those beautiful vistas you see in paintings, untouched by humanity and drink the clear stream water. Then spend the next few days doubled over in pain from all the parasites that live in the water, having arrived there from animal feces.