Nice post which detail many aspects of veganism. Personally I love vegan food but I think it is not suitable for human species as it is. The importance of meat and fish (especially) is significant, you can imagine a diet without Omega 3 and 6...but surely, an increase of vegan's food in our diet has both a good effect on our health conditions and on the reduction in CO2 emission...I wrote an article about that :o)
There is plant-based food sources for practically every possible nutrient bar 1 or two and vegan supplements for the limited nutrients not obtained easily from food. With thorough nutrient planning, there is no nutritional downside to veganism.
There is a well known effect related to deficiency of vitamin B12 for a pure vegan diet. The only way to get the necessary amount of B12 vitamin would be to use "fortified" food which are in any case linked to non-veganism diet. The risks related to such deficit are very serious. Veganism is anyhow a good practice but I think a minimum percentage of non-vegan foods like meat, fish or honey has to be considered to have a better healthy condition.
Vegan B12 supplements, nutritional yeast and fortified foods are easily attainable, in mass dosages too. B12 defiancy and any nutrition deficiency, is a case of negligence, there is no reason a vegan shouldn't be able to obtain the same nutrient as omnivores, with a little forethought.
I take 800mcg of B12 daily, is which far more what's obtainable through meat, fish and dairy.
I'm not sure about if the production process of vitamin B12 is totally not linked to meat, eggs or other type of animal foods. I red something about the need of some natural bacteria for the production of B12 vitamin also. In addition, if the veganism is a sort of natural way to feed ourselves, why do we have to get some pills or supplements?
B12 supplements are 100% vegan. Vegans can obtain all necessary B12 intake through said methods, it's undisputable. The reasoning for needing b12 supplementation is likely due to the absence of bacterial in modern food and lifestyles, we no longer eat food fresh from the ground or make make frequent contact with dirt and mud. Regardless supplementation is an perfectly acceptable method of nutrient intake.
If humans are designed to eat meat, why is it so carcinogenic (causes cancer) and why do we have to cook it to safely ingest it? The vegan diet is largely known to reduce the risk of heart disease and cancer.
It is really possible with no problems to health to eat some kinds of meat even not cooked (this is also an old practice very common in countryside villages), the only requisition is to get the meat fresh. I agree about the non-healthy condition of a 100% meat-based diet anyhow. What about eggs and fish?
I think that a correct diet has to be balanced with the right percentages of the whole nutrients without getting it through supplements. If the totally vegan diet is the best and right way to feed the human specie, why do you need to get pills?
Finally, it is not medically demonstrated that the meat causes cancer, whilst it is well-understood that the pollutants in general increased the cancer in the industrialized cities...
It was mentioned previously, B12 is a bacteria. Modern lifestyles and agriculture leads to less exposure to bacteria, thus less B12. B12 isnt produced in animals or plants, its solely synthesized via bacteria. Its common practice in the meat industry to inject cattle with B12 supplements, which are vegan, one way or another you are taking a supplement. Modern agriculture has also lead to decreased nutrient quality of food, thus a reliance on supplements to some degree is needed. Visit a nutritionist and get your blood checked, I can almost guarantee they recommend supplementation.
Cobalamin is present in many foods. Liver, eggs and fish. If you choose organic foods, so not exposed to modern technique, the support of B12 is assured. Really, I had not B12 deficiency in the past due to my non-vegan diet. I do not want to have the addiction to B12 pills due to vegan diet. This practice is not natural. Try to choose certified organic foods instead, supporting the old agriculture and farming practices.