B12 is actually a crucial substance and deficiency can cause serious problems such as nerve damage, low energy and problems utilizing calcium which can lead to osteoporosis. B12 is also crucial for brain damage and some theories state that we may have even become omnivorous in order to help develop our brain function. While it is possible to get B12 through fortified sources, this simply isn't as beneficial as getting it naturally as again it isn't as bio-available. By supplementing your diet with B12, fatty acids and BCAAs you can almost counter the negative side effects of vegetarianism on your health, but you will be spending a lot of money in order to do so and popping a lot of pills.