If you're allergic to brewer's yeast then it's obviously not a good thing for you to be taking! I'm pretty sure that "brewer's yeast' and "nutritional yeast" are pretty much the same thing.
Farmschooler- that's interesting about the yeast, but I still wonder if it's truly applicable to the way we're talking about using yeast on this thread. We're not talking about baking with yeast, we're just talking about consuming plain yeast as a nutritional supplement/superfood, so it's not going to affect the digestability of the nutrients in bread or anything else. The link you quoted didn't talk about the nutritional qualities of the yeast itself, when used plain or sprinkled onto already cooked foods.
I've been taking my yeast most days, but I finally found some kosher liver again!! I bought 4 1lb packages, but I won't cook any of them until next week when the kids are back at school (well, 2 of them anyway.