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.

Researchers said the study's findings suggested the need for older adults to take supplements, even if their levels were considered "normal"