Not sure if this subject has been brought up before - I couldn't find it but apologies if it has.
During the course of reading about Pernicious Anaemia, I came across the following study which essentially says that methylcobalamin is not on its own an adequate source of B12 replacement therapy as it can't be broken down into adenosylcobalamin - another vital molecule needed for B12 absorption... ncbi.nlm.nih.gov/pubmed/251...
Many other sources and studies don't appear to mention this, which has left me confused...
The licensed injections in the UK are usually of the hydroxocobalamin variety, and in the US I understand they're cyanocobalamin. Both these forms, unlike methylcobalamin, can be broken down into adenosylcobalamin, or so it is claimed... (although they are not as 'bioavailable' as the methyl form).
So if people like myself, with the IF and/or PC antibodies, or for any other reason, are unable to absorb (presumably all forms of) B12 gastrointestinally, where does that leave us with respect to adenosylcobalamin?
I am not a medic or a biochemist so I'm hoping I've just made a layman's misinterpretation of what is a very complex area, but any views or advice on the matter would be greatly appreciated.
Many thanks, Doug