In your article on Nettle, you say that cooking it keeps it from stinging. Why is this?
Dr. J. P., Salt Lake
Oh, what an excellent question! And shame on me for not addressing it in my article. Since I can't find a readily available scientific explanation, I will give you my best guess.
The simplest explanation is that heat causes the stingers to poop out their inflammatory contents, which then get diluted by the rest of the cooked material. Since they are dilute, they are less potent. Realize that a nettle stinger injects a teeny tiny area of your skin with a relatively concentrated dose of inflammatory mediators.
Sometimes heating molecules causes them to degrade, that is, to change into other things which don't have the same activity. But I suspect that is not going on with these molecules. Some molecules are more fragile than others.
Also, heating molecules sometimes gives them enough energy to leave the pot, so to speak, and fly around the room! We call that evaporation. If the molecule has a smell, you can detect such escapism when the molecule flies up your nose. But these are not very volatile (easy to evaporate) molecules, so I don't think that is the case, either. These molecules are too attracted to water to want to leave the pot.
I'm going with my dilution theory--but that's just a guess.
Stinging nettle, Urtica dioica