What an urban myth that natural means safe. Arsenic is natural, but I wouldn't want to eat any. Carbon monoxide is natural, but I wouldn't want to breathe any.
I think the big thing here may be all of the highly publicized news reports about adverse reactions to pharmaceuticals. Since these are regulated (let's not get into how well right now), the reactions must be reported. And what with the large number of people taking them, there are many more people with adverse reactions. NBE is pretty much done on an individual basis and no one reports that their friend took an excessive amount of some herb or supplement and had a severe reaction, but that can happen.
Sorry for the rant, but natural things can kill you every bit as dead as pharmaceuticals.