Thanks @PeterPositive for the correct link. Last weekend I listened to a talk about " Genetic variation in detoxification" and the professor that lectured mentioned grape fruit juice and milk thistle as two things among others to be careful with not to lower the detoxification in Phase I.
If substances proceed undetoxed to Phase II (due to too low enzyme activity for some reason-s) , more toxins than before might be present.
If substances proceed undetoxed to Phase II (due to too low enzyme activity for some reason-s) , more toxins than before might be present.