Do a bit of research as to what nutrients humans NEED, not just through 'diet choice'.
Not being intentionly obtuse, but I can't be bothered to look up vegan diet links, at the moment.
Just to add, if veganism is that healthy for anyone, why is there a huge market for supplements, for vegans to add the essential vitamins, minerals, fats and proteins to their diets, which are lacking in plants?