This site is a pretty convincing read. I don't mean to be inflammatory. I'm just exploring the various diets. I became vego at 14 and now at 33 am combatting some health problems and exploring why. Also, the vegos around me that I have known for years are also having lots of health problems and their children too. I acknowledge this could be a number of factors: improper nutrition, processed foods, stress, who knows..
A year ago, I found the Weston Price Foundation and it speaks to me (Vegos like their cookbook too because it gives lots of traditional recipes and basically promotes whole food that is properly prepared - eg. fermenting or soaking grains).
Anyway, if you feel so inclined, read this site which WP Foundation recommends: http://www.second-opinions.co.uk/veg_index.html