After leaving my reply, I ran into this article. I found it to be very interesting. I'm sure you will as well.
The first question I have is that if L-Trytophan is harmful, even when uncontaminated, why is this result not duplicated in baby formulas ect.?
He makes a good circumstantial case for over whelming greed.
http://www.ceri.com/trypto.htm