This was a quote from Dr Micheal Colgan:
If you use glutamine, you whack your body with ammonia. Unless kept absolutely dry, glutamine powder degrades into ammonia and pyroglutamic acid. It degrades even if you put it in solution only a few minutes before you drink it, and even in the stomach if you take it dry. Consequently, glutamine is not used with catabolic patients because it adds to their ammonia burden.
Ammonia is toxic to all cells, reduces the formation of glycogen, and inhibits the energy cycle. It has devastating effects on brain function. We still don't know how much it contributes to fatigue, but we do know that the higher the blood ammonia, the poorer your performance.
Apparently, Glutamine supplementation isn't as wholesome as it appears to be.