" The World Health Organization (WHO) recommends that men and women obtain 5% of their calories as protein. This would mean 38 grams of protein for a man burning 3000 calories a day and 29 grams for a woman using 2300 calories a day. This quantity of protein is impossible to avoid when daily calorie needs are met by unrefined starches and vegetables. For example, rice alone would provide 71 grams of highly useable protein and white potatoes would provide 64 grams of protein.8
Our greatest time of growth—thus, the time of our greatest need for protein—is during our first 2 years of life—we double in size. At this vigorous developmental stage our ideal food is human milk, which is 5% protein. Compare this need to food choices that should be made as adults—when we are not growing. Rice is 8% protein, corn 11%, oatmeal 15%, and beans 27%.8 Thus protein deficiency is impossible when calorie needs are met by eating unprocessed starches and vegetables.
The healthy active lives of hundreds of millions of people laboring in Asia, Africa, and Central and South America on diets with less than half the amount of protein eaten by Americans and Europeans prove that the popular understanding of our protein needs is seriously flawed. "
B12 is made by microorganisms that are found in the soil: http://books.google.no/books?id=Fn_EAmODnIkC&pg=PT202&lpg=PT202&dq=colin+campbell+microorganism+b12&source=bl&ots=5kzTTuMrlE&sig=xdee6LkL8OOG-nfknVeDbJrKIUc&hl=sv&sa=X&ei=vZNKU_vjKaqo0QWRloDwCA&ved=0CFUQ6AEwBQ#v=onepage&q=colin%20campbell%20microorganism%20b12&f=false
You are healthier on an average vegan diet compared to an average omnivore diet:
Humans can be healthy on a varied vegan diet (with B-12-supplement or B-12 fortified foods):