It might just mess with your already messed up emotions. I know lack of certain vitamins can make one irratable, many vegans and vegetarians I know are cranky people. So for the sake of yourself and others around you, find other ways to get all of your vitamins and minerals. I'm about to shove a funnel in a friend's mouth and spoon in the meat if she gets any crankier, she wasn't like this before she went vegan.