Adenosylcobalamin

[forummm]

Hey guys, what is the difference between this form and the other main forms (metyl and hydroxo)?

Is it worth giving the injectable version a try if one can get them?

Regards

[Gambit62 Administrator]

adenosyl is an analogue of one of the two forms of B12 used in processes inside cells. methyl is the other analogue. Both of these forms are quite unstable. Both are also generated inside your cells by adding either a methyl or an adenosyl complex on to the B12 molecule.

B12 can be bound to many different complexes - cyano, hydroxo, methyl and adenosyl are the complexes that human biochemistry can split out to leave a cobalamin element that can be bound to particular proteins in the blood - TCII is the form that is bound to the protein that allows it to pass into your cells and be used in your cells. In this process the protein is separated from the cobalamin part and then combined with either a methyl or an adenosyl complex inside the cell depending on which process the B12 is going to be/needs to be used for.

Personally I don't think it is worth trying to get hold of injectable adenosylcobalamin - it is extremely unstable - even more so than methyl - and very expensive if you can find a source at all. I do use some adenosyl but in the form of high dose sublinguals - which sort of work for me.

[fbirder in reply to Gambit62]

Just a bit of clarification...

B12 is bound to one of two proteins in the blood (TC or HC) in the form that was absorbed from the gut. Normally that would be hydroxocobalamin (if the B12 is from food or from a hydroxocobalamin injection). If cyanocobalamin has been taken then that will be bound, unaltered, to the proteins. Methylcobalamin and adenosylcobalamin are both fairly unstable so are likely to have already broken down to hydroxocobalamin. But any that survive will also be bound to the blood proteins unchanged.

Once the B12 (bound to the TC protein) enters the cell the TC is removed as is the top ligand (the hydroxo-, cyano-, methyl-, or adenosyl-) to form cob(II)alamin. This is then transported to the part of the cell where it is needed. Once there it is either bound to the enzyme methionine synthase (while attached it, very briefly, forms methylcobalamin) or it is converted to adenosylcobalamin.

[fbirder]

All forms of B12 are identical once they enter the cell.

ncbi.nlm.nih.gov/pmc/articl...