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Of the B vitamins, vegans (and to a lesser extent, vegetarians) only need to supplement B12. B12 is produced by bacteria but can be obtained in meat and animal

Of the B vitamins, vegans (and to a lesser extent, vegetarians) only need to supplement B12. B12 is produced by bacteria but can be obtained in meat and animal products. Historically we got plenty from unsterilized water.

chmod600 5y ago
Do you have a citation about the unsterilized water? I would guess that lots of things had bacteria, but not in large enough quantities to supply enough B12. It would need to be accumulated somehow. Cows have special hardware in their digestive tract to cultivate bacteria that can supply the B12. Why would that exist if cows could just get it from unsterilized water?
- cyounkins 5y ago
  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
  - chmod600 5y ago
    Interesting. Might be a case of "all of the above", where the people who get into real trouble do so because they defeat all the sources.

chmod600 5y ago

Do you have a citation about the unsterilized water? I would guess that lots of things had bacteria, but not in large enough quantities to supply enough B12. It would need to be accumulated somehow. Cows have special hardware in their digestive tract to cultivate bacteria that can supply the B12. Why would that exist if cows could just get it from unsterilized water?

cyounkins 5y ago
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
- chmod600 5y ago
  Interesting. Might be a case of "all of the above", where the people who get into real trouble do so because they defeat all the sources.