Regarding "100%" Vegetarian tribes:

"It is true that Hindu vegans living in certain parts of India do not suffer from vitamin B12 deficiency. This has led some to conclude that plant foods do provide this vitamin. This conclusion, however, is erroneous as many small insects, their feces, eggs, larvae and/or residue, are left on the plant foods these people consume, due to non-use of pesticides and inefficient cleaning methods. This is how these people obtain their vitamin B12. This contention is borne out by the fact that when vegan Indian Hindus later migrated to England, they came down with megaloblastic anaemia within a few years. In England, the food supply is cleaner, and insect residues are completely removed from plant foods (16)." [Weston A. Price Foundation]

Howard