Moondaughter mentions anemia. I, too, had a strange anemia about thirty years ago. It was not one of the common names and I don't remember much except that my GP was *very* concerned. I had eliminated red meat from my diet and reintroducing it cured the problem. I don't recall any mention of anemia being a risk factor for PD, but who knows.

One thing I have been thinking about is cast iron cookware. It is a significant source of iron in the diet and if one cooked acidic foods such as tomatoes then you should be approximating "ferric ascorbate". I remain convinced that PD came with the Industrial Revolution, but cast iron pots existed well before then. There should be a direct tie between their use and PD, I think.

But is there?