Is that that St John's Wort patients have been extensively studied and it has been found not to have any dangerous effects? Or is that that an insubstantial nu

Is that that St John's Wort patients have been extensively studied and it has been found not to have any dangerous effects? Or is that that an insubstantial number of studies on St John's Wort have been carried out? When I tried to find out about this (years ago, pre-Wikipedia I think) I couldn't find any substantive research. For all their faults, pharmaceutical products are well-studied, especially the ones that have been on the market for some time.