I got this from Dr. Greger at NutritionFacts.org, "We presumably used to get B12 drinking out of a mountain stream or well water, based on studies showing veget

I got this from Dr. Greger at NutritionFacts.org, "We presumably used to get B12 drinking out of a mountain stream or well water, based on studies showing vegetarians in developing countries who drink purified water appear to be at higher risk." [1]. He references a paper [2] which states "Logistic regression analysis showed independent association between use of RO water and Vitamin B12 deficiency" in Western India. That evidence isn't as iron-clad as I would like, and I haven't been able to find any study directly measuring B12 in city/well/stream water. I don't know much about cow digestive systems, but I know evolution has created many weird solutions across different animals. The cow GI system is very different from humans (4 large stomach parts, sometimes referred to as separate stomachs) which is different from cats (obligate carnivores). [1] https://nutritionfacts.org/video/the-symptoms-of-vitamin-B12-deficiency/ https://nutritionfacts.org/video/the-symptoms-of-vitamin-B12... [2] https://www.ncbi.nlm.nih.gov/pubmed/27437269 https://www.ncbi.nlm.nih.gov/pubmed/27437269