The cut-off between normal and deficient vitamin B12 blood levels varies by lab, but anything lower than 200 or 250 pg/mL is usually considered deficient, according to the NIH. However, there are other markers that can suggest you’re low in B12, so it’s really best to talk to your healthcare provider about your results if you get tested.

The study's findings suggested a need for older adults to take supplements, even if their B12 levels were considered "normal"

The latest research in the Annals of Neurology suggests that even B12 levels considered "normal" may still be linked to neurological damage. The study on people with B12 levels above the current deficiency threshold,