It has a lot of B in it. Both vegemite and marmite are prepared using a base of carrots(the veg. source).

There is a trick in spreading it. You need to start with a buttered, crisp toast then you take a tiny tiny portion of vegemite.marmite and quicky spread it before the butter melts completely. Without the toast, I don't know what one can do with marmite/vegemite, except dissolve it in a cup of water and drink it like a soup like one makes a quick beef tea using bovril.