His reasoning is that glutathione is not a "true" chelator but only a redistributor of mercury because it doesn't have a double thiol bond. Therefore, glutathione and NAC and pretty much all other sulfur compounds are to be eliminated due to the fact that they'll pick up mercury and leave it somewhere else in the body instead of having a strong "true" bond that will bring it out of the body.
That being said, I don't buy it. People forget that Andy is just another researcher and he speaks the part of a chemist. Chemistry isn't everything in medicine. There are people that do well and actually REQUIRE glutathione. People who lack GSTP1 and have genetic mutations that produce less or less effective glutathione. These people have their natural and most potent antioxidant depleted. Some people are not lacking GSTP1 such as myself, and I seem to have ample amounts of glutathione. For people like myself, maybe i could have an adverse reaction to too much of it but I've had a glutathione IV push and didn't really feel all that much better or worse.
Oral glutathione is apparently largely ineffective in being absorbed into the body's bloodstream, but liposomal and IV will work great. Even sublingual may work well. However, people do feel well and a difference from taking oral glutathione so it's hard to say. It is very good for the GI tract so the benefits maybe from helping the GI tract and the entire immune system from oxidation.
You can also take NAC or ALA as precursors to boost your glutathione levels but be aware that ALA can cause chelation.
The thing I don't get about andy is when he makes statements like "half the people who take it get worse". Where is he getting these numbers?? From his yahoo groups? I'm sorry but he's not a medical practitioner. A researcher may know things very well in terms of specifics but they lack clinical experience and patient evaluations, just like doctors with lots of clinical experience lack the time to do their own specific research most of the time. I have his book and he does have a big list of sources at the back but there are so many claims throughout the book telling doctors what they should or should not do that go uncited. I don't know where this information is coming from. I would take those statistics with a grain of salt. He does make very good points and is right about many things and as far as I'm concerned, he's on the same SIDE as everyone else, including the DAN doctors and their methods which he hates because it's all working to the same goal. But he isn't right about everything.