The NHS website states " PA is the most common cause of b12 deficiency in the UK". So why do NHS doctors not read that? It goes on to say "Some people can experience problems related to a vitamin B12 deficiency, despite appearing to have normal levels of vitamin B12 in their blood.
This can happen as the result of a problem known as functional vitamin B12 deficiency, where there's a problem with the proteins that help transport vitamin B12 between cells.
This results in neurological complications involving the spinal cord."