This question already has an answer here:

As far as we know, vegans need to supplement with B12 to prevent deficiency due to a higher risk of such.

How long does it take for B12 deficiency to develop, if a vegan person does not take any B12? If there is no access to supplementation, how long is it possible to live without any health risks like nerve damage etc.?

marked as duplicate by Zanna, Community Sep 20 at 12:41

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • P.S. I understand it is hard to give an estimate, depends on many factors, but like inaccurate average values would be also ok. – Maxgmer Sep 19 at 9:15
  • Some recent blood tests were good for everything except low B12 but I have not had previous tests so I don't know when it developed. I am now taking a supplement but it disappoints me that I need to; I prefer natural sources. – badjohn Sep 19 at 10:09
  • 2
    It says you need to inject B12 every 2~3 months basis. – Knowledge Drilling Sep 20 at 15:15