I've confused you little bit with the name "David". Mikey mentioned this name at the beginning of this message. David is a health practitioner in UK. I was answering you but also little bit reacted to Mikey message and I mentioned David's name. Sorry for confusion.
I like the book from dr. Lam, it helped me understand a lot of problems. I've not read the web pages so I can't compare.
Fortunatelly I have no problem with NAC, gluthatione.