Question: Does high B12 mean it’s not getting into the cell?
The right way to address that would be to measure serum or urine or both methylmalonic acid MMA, and that's a functional marker that's very specific to B12. If B12 was not getting into the cell, then methylmalonic acid is going to be high.
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DISCLAIMER: I have a PhD in Nutritional Sciences and my expertise is in performing and evaluating nutritional research. I am not a medical doctor and nothing herein is medical advice.