Anything that once had a face...cows, fish, ants....you name it! LOL
I personally cannot tolerate soy unless it is in a fermented form so I haven't done a lot of research on it...although I'm real leary about it being used excessively...and it is in everything these days! My understanding is that it is almost as mucoid-forming as meat so at least in that way it doesn't have any major health advantages.
Do you mean L-arginine? It does help metabolize ammonia and has been found to improve decreased liver function in animals. It shouldn't be used continuously for long periods of time, though... and no more than 4 grams a day. It can increase growth hormone effect (at 3-4 grams per day) and also potentially alters insulin and carb metabolism so diabetics need to be cautious with it.