The 2 year store of B12.: Hello All, I... - Pernicious Anaemi...

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The 2 year store of B12.

EVMD profile image

Hello All,

I have been trying to understand the B12 store as we are always being told by the doctors. As I understand it - and I may be wrong, we are born with a 2 year supply which may kick in when the body is not receiving enough (as in B12 Def. or PA.)

If we are always "in the black" we do not deplete it, otherwise,e if we rely it to top us up periodically, we will eventually go into the "red".

Am I right or not. Look forward to any comments. Thank you.

Kindest regards to all sufferers and thanks to all advisers. Its a minefield isn't it.


6 Replies

As I understand it, if you have PA and have intrinsic factor antibodies it doesn’t matter how much B12 your body has stored. You still need the IF to utilise the B12.

fbirder profile image
fbirder in reply to JanD236

No, IF is only required to absorb B12 from the gut. It doesn’t stop the body using the stuff it already has. But it can mean that stores are depleted faster (see my other answer).

JanD236 profile image
JanD236 in reply to fbirder

Ah ok, thanks.

EVMD profile image
EVMD in reply to JanD236

Thanks Jan that's what I thought. Trouble is, Docs try to say that this 2 year store is always there which is nonsense.


In normal people there is a store of B12 that should last many years. They keep that amount topped up by eating food that contains B12. Some of the B12 gets eliminated in the bile into the gut. There it binds with Intrinsic Factor and gets reabsorbed back into the blood. It’s called enterohepatic recirculation.

In addition, the body doesn’t really use up B12. It gets recycled in the biochemical processes it is involved in. That’s why we actually need a very small amount of top-up.

If you have PA then you don’t absorb B12 from the gut. But the amount in the body also decreases. That’s because the B12 in the bile doesn’t find any IF to bind to, so it doesn’t get reabsorbed. Slowly the stores of B12 decline. Symptoms slowly get worse and worse.

EVMD profile image
EVMD in reply to fbirder

Thank you fbirder,

That more or less agrees with my own explanation I think!



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