A lot of people try to discount veganism because we vegans are told we must supplement with B12. There are vegans who do not supplement because they try to get enough B12 from their diets, but all the reports I read from experts state that there is not enough B12 in plant foods, and that the bacteria in the dirt is cobalt depleted and nutrient poor now, and, therefore, is not reliable. Most reports say that EVERYONE should be supplementing with B12!
Meat eaters claim vegans' diets are deficient because they know that we have to take a supplement. Now I could eat a lot of already fortified soy milk and cereal (which I do) and I could truthfully claim I don't take a pill form supplement, but my food is already supplemented - just as cows milk is fortified with Vitamin D and bread and flour are fortified with folate. (And meat eaters are still deficient in more vitamins than vegans, in general.) B12 is so important, it's better not to take a chance on being deficient. By the way, 40% of people are deficient in B12. Meat eaters - take your B12!!!!
I thought that, technically we vegans could easily eat dirt or feces to get B12 (who would want to), but the soil is too poor now to take that risk. What meat eaters do not realize is that they also supplement their diets with B12. Yes, you, the meat eater, take many supplements - you just don't realize it. You just run the supplement through an animal.
Very few people eat grass fed beef and even those who do, are rarely consistent about it - they go out and eat meat in restaurants or at friends' houses that is not grass fed. Why am I mentioning this? B12 comes from bacteria that is in the soil and meat eaters used to get B12 from the cows who absorbed B12 naturally from dirt. Now, however, meat eaters get B12 by cows who spend either their whole lives or the last six months of their lives being fattened up by grains that are supplemented with B12! So, cows are eating supplements and meat eaters are absorbing cows' supplements into their systems. Again, even the grass fed cows are eating from soil that may not be rich in B12. Also, cows do contain bacteria in their guts that manufacture B12, but the antibiotic use on the farms kills their gut bacteria! I should highlight that last part! I will repeat it: . . . the antibiotic use on the farms kills their gut bacteria!
So you supplement. You may now stop thinking vegans' diets are insufficient because we choose supplementing. I eat a tasty cherry flavored chewable B12 supplement, which I highly recommend over eating an unknowable amount of B12 that has been ingested by a cow as a supplement and consumed by you through the animals' flesh.