> The paradoxical B12 deficiency might have a relation with the inactive form being supplemented.
Yup, not everyone can convert cyanocobalamin or hydroxocobalamin to adenosyl-/methylcobalamin. Especially in severe cases, anecdotally I’ve seen people not make progress with the standard cyanocobalamin injections, but then make huge progress with methylcobalamin injections. Unfortunately, methylcobalamin is often not preferred in injectable form due to very quick degradation into hydroxocobalamin upon exposure to light.
Yup, not everyone can convert cyanocobalamin or hydroxocobalamin to adenosyl-/methylcobalamin. Especially in severe cases, anecdotally I’ve seen people not make progress with the standard cyanocobalamin injections, but then make huge progress with methylcobalamin injections. Unfortunately, methylcobalamin is often not preferred in injectable form due to very quick degradation into hydroxocobalamin upon exposure to light.