I am one of those folks who simply is not healthy as a vegan or vegetarian, of which I've met many. My theory is that just as some of us have a body chemistry that does not produce enough insulin or thyroxine or stomach acids, perhaps some of us can't make enough of the vital amino acid taurine, which is found only in animal-based foods, especially meat. I've met glowingly healthy ovo-lacto vegetarians and vegans whose bodies clearly DO make enough taurine. I have a long time friend who is largely vegan, sometimes eats eggs and cheese....for the years I've known him he's complained of chronic low energy, often has colds that last for months...in view of taurine's role in fighting infection and generating cellular energy, I can't help but wonder if he is deficient in taurine? Nice to have an open mind on issues regarding diet and health, both of which are personal matters that only we can know and address.