> Vitamin B12 deficiency in the US and the UK is estimated to occur in about 6 percent of those under the age of 60, and 20 percent of those over the age of 60.[1] In Latin America rates are estimated at 40 percent and they may be as high as 80 per cent in parts of Africa and Asia.[1]
All experts recommend vitamin B12 supplements for vegans, vegetarians and older people.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4042564/
https://www.ncbi.nlm.nih.gov/pubmed/17959839
https://www.b12-vitamin.com/algae/
From https://en.wikipedia.org/wiki/Vitamin_B12_deficiency:
> Vitamin B12 deficiency in the US and the UK is estimated to occur in about 6 percent of those under the age of 60, and 20 percent of those over the age of 60.[1] In Latin America rates are estimated at 40 percent and they may be as high as 80 per cent in parts of Africa and Asia.[1]