I heard a guy on the radio last night saying that the yeast used to make beer contains a whole lot of vitamins and nutrients, including B12. He likened it to the yeast in Marmite.
Naturally, if this is true, it will make many of us very happy to know that beer is good for our body (I already know it's good for my soul)
Still, I have my doubts about this claim... that said, I've been a reasonably healthy vegan for over ten years (including my fair share of the amber stuff) - a month ago the doc checked my B12 and said it was fine. I don't take supplements and very rarely if ever eat anything fortified with B12.