Ok, just have to share an interesting case I saw this week. A preteen boy with a history of a severe facial rash when he eats fermented soy products like natto and soy sauce (mom is part Japanese and they eat a lot of traditional Japanese foods). Oddly he doesn't react at all to soy that isn't fermented, like edamame.
I do a quick google search and learn something new - apparently natto has a compound called poly gamma glutamic acid that is made during the fermentation process. It's been reported as a cause of anaphylactic allergic reactions, mostly among surfers in Japan - because jellyfish stings contain the same compound! How cool is that?
My young patient needs to avoid all fermented soy (he got some accidentally in beef jerky that contained soy sauce) and I prescribed an epipen for emergencies just in case he progresses to anaphylaxis.
