Hal, that is interesting.
This isn't scientific, but I also noticed that kale seems to relieve muscle pain. By chance I had a flare-up of shoulder pain after exercise, and also happened to eat a big handful of raw baby kale leaves right after the symptom started. Within a few minutes the pain subsided, although it normally would take several hours, at least, for the pain to die down.
I didn't think it was related until it happened again. Again, I ate raw kale with nothing else. Then I tried it a few more times in a spirit of inquiry.
My( totally amateur and unscientific) "experiment" was to eat kale if the shoulder ache flared up, and eat nothing else with it to rule out other foods. (I didn't take any pain medications either, having decided that I would try to find a more naturaI path to dealing with muscle pain). Kale always seemed to work, and very quickly too. I tried other raw greens and nothing happened (except that they tasted good LOL).
I told my physical therapist and she said she didn't know of any research that supported pain-relieving properties of kale. But eating kale was a good thing anyway so there was no harm in doing it.
I am not claiming this anecdote proves anything, but kale seems to work for me
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