The more likely explanations of vitamin B deficiency:
https://pubmed.ncbi.nlm.nih.gov/19892133/
or
https://www.sciencedirect.com/scienc...72975208021301
Simply due to processed grain, hulled rice, white flour and the like. That's what's behind the movement toward "natural foods." Of course Texas A&M thought it was meat related!
As it was sung, "we get the government we deserve."
That said, I do take a sublingual B12, not being a meat eater. OTOH:
https://bbarrx.com/blog/2018/7/20/b1...not-the-answer 
more realistically
https://academic.oup.com/nutritionre.../2/106/1820655