As I understand it, there is a problem with whey when it is processed in a particular manner that alters the proteins. The result is that glutamic acid is created and that is a potent excitotoxin. Dr. Blaylock, who literally wrote the book, advises against it when labeled as "whey protein concentrate.'

A site worth visiting is http://www.rtnc411.org/tlinks.html

The idea of certain proteins being altered by heat processing is particularly interesting to me because I have developed a heck of a sensitivity to such over the last couple of years. It has gotten to the point that if I get a hit of MSG then it is as if my meds have completely stopped working for four to six hours. It comes on in about 10 to 20 minutes.

One of the things that does it is the new (in the US but common in Europe) "ultra high temperature" pastuerizing of milk. Ironically, organic milk is usually done that way for a longer shelf life.