This is a fascinating thread. I just wanted to chime in to add that I was a vegetarian for 20 years and quit just a few months ago due to extreme constant fatigue and largely because I am hoping the animal protein and heme iron will help my hair growth. I have way more energy now, I don't look as pale and sickly anymore, I have much less body odor (I used to stink after workouts and no longer do), but I do worry about my karma.