I have found it mordidly interesting that those 'lab' tests usually include injecting into a lab animal enormous amounts of whatever chemical or substance the researchers are being paid to promote. Caffeine can kill you, since it killed this here rat, but we didn't tell you that we injected a third of it's body weight in caffeine into the little critter. I weigh about 140. If I injected 45 pounds of liquid caffeine into me, I'd die too. Of course, if I ingested or injected that much of anything, all in one go, I'd be just as dead.
I used to infuriate my dietetics teachers (back when I was a dietetics major) by wearing an 'Eat Right, Exercise, Die Anyways' t-shirt, often with a pack of smokes in the pocket. And when they started in on quality of life vs quantity of life, I'd always go with quality, telling them that I'd rather die at 50 of a heart conniption surrounded by friends and family, eating a big medium rare steak, big baker with lots of butter and sour cream, with a beer in hand, than to waste away in a nursing home at 90, friends, family and loved ones gone before, being fed strained peas by a well-intentioned nurse. Needless to say, I'm not a dietician.
I must say that I enjoy talking with die-hard vegans. They never seem to like to answer where they get their B-complex vitamins, which are found only from animal sources. The lack of those vitamins will and do cause serious health situations, which are not easily rectified. So, if someone actually likes eating bean curd and seaweed, and the myriad of soy products, let em. I just pray they don't invite me to dinner.