Why Your Vitamin B12 Deficiency Isn't Resolving
There are many reasons why someone may have a hard time resolving their vitamin B 12 deficiency - including the form of vitamin B12 they have been taking as a supplement.
Some form of vitamin B 12 are more active than others and much more bioavailable. If you are taking a less active form of B 12 then this could potentially be why you may still struggle with symptoms or struggle with seeing your labs improve.
The most bioavailable active forms of vitamin B12 are methylcobalamin and adenosylcobalamin while less active forms are cyanocobalamin.