Way before people register B12 deficiency on a blood test, their ability to use the B12 they have, has failed. This means they do not have ‘Pernicious Anemia’ BUT they do have a problem with lack of B12 in the right places. People in the ‘grey zone’ can be detected with the laboratory test that measures Methylmalonic acid (MMA). This metabolite rises in people with poor B12 usage.
For the last decade the directive from the USA has been, supplement for 6 weeks with sub-lingual B12 that absorbs through the mouth, and see if you feel better OR symptoms abate. If they do, then you were B12 deficient. Continue reading