I wouldn't go so far as to say that it BLOCKS cortisol...
But strictly speaking...as any amino will....it can certainly help reduce the severity of a catabolic state - assuming you are not getting enough of it...
the effervescent supposedly has some better resluts with some ppl......i can somewaht see why.....buffering your stomach acid......either that or you have to take about 40-60 grams a day on empty stomach to get anything serious out of it. Or in dieting it works relatively well. As far as mass i would find proteins high in glutamic acid......and also wheat gluten etc......