There was a small town in the US somewhere (I can't remember where) and apparently they had just the one butcher and he used to provide hamburger meat for the whole town pretty much, and apparently the whole town used to eat the hamburgers pretty rare.
When the whole town (just about) ended up with thyroidosis, they found he'd been including cow thyroids in the makings for the hamburgers, and because they were generally served rare, the thyroxin (I think that's the name of the chemical) wasn't being destroyed.
Anyway, they stopped eating thyroids and they all got better.
The moral of the story is: Always cook your hamburgers well.
