Why doesn't hydroxocobalamin work for Freddd and some other folks?
Hi, Freddd and the group.
I've been puzzling over this question: Why doesn't hydroxocobalamin work for Freddd and some others, while methylcobalamin and adenosylcobalamin do?
Now I have a possible answer, which I would like to share.
First, as I have reviewed in the past, the normal transport of B12 and its import into the cells involves its binding with transcobalamin for carriage in the blood, and the linking of transcobalamin with its receptors on the cells for bringing the B12 into the cells. Then, the normal B12 processing within the cells involves stripping off the beta ligand (methyl-, adenosyl-, aquo- or cyano-) and reconstructing appropriate amounts of methylcobalamin and adenosylcobalamin for use by the cells.
Freddd has noted that the normal intracellular B12 processing does not work well in his case because of an inborn error of metabolism (i.e., a genetic mutation in one or more of the intracellular B12 processing enzymes).
Fortunately, by a persistent and exhaustive effort on his part over many years, he has found that he can compensate for this deficit by direct application of large dosages of both methylcobalamin and adenosylcobalamin (together with methylfolate and certain cofactor nutrients), delivered sublingually (or by injection) directly into the bloodstream. This does the trick for him, and for a number of other people with whom he has interacted. On the other hand, he reports that hydroxocobalamin doesn't work for him.
Meanwhile, based on the work of Dr. Amy Yasko, primarily in autism, I proposed use of sublingual hydroxocobalamin as part of the socalled "Simplified Treatment Approach" for ME/CFS. Clinical study of this protocol has shown that about two-thirds of people screened to have an "official" diagnosis of ME/CFS, including post-exertional fatigue and malaise, experienced a significant improvement from this protocol over a period of several months.
So how can this be?
Well, it seems likely that Freddd's treatment approach is bypassing the normal transport, import and processing of B12, and instead is relying on diffusion of methylcobalamin and adenosylcobalamin directly through the phospholipid bilayer plasma membranes of the cells to deliver these cofactor forms of B12 for use by the cells without further processing. I think this is the key to the explanation of the failure of hydroxocobalamin to work for Freddd.
It is known that in order for a molecule to diffuse through the cell membrane, it is important that it be uncharged, i.e. a neutral molecule. The reason for this is that if a molecule in an aqueous (i.e. water) solution (such as blood plasma) has a net positive or negative charge, the surrounding water molecules will orient themselves so that their oppositely charged ends will be closer to the molecule, on the average, forming a "cage" around the molecule. In order to pass through the cell membrane, the molecule would have to shed this cage, but the binding energy of these water molecules makes it difficult for this to happen. Therefore, charged molecules generally do not pass through cell membranes readily. ( There are exceptions to this, involving "porins," but they are not involved with B12, as far as I know.)
(Note that this phenomenon occurs because a water molecule has a dipole moment; that is, its center of positive charge is separated by a small distance from its center of negative charge. This results from the shape of the molecule, in which the two hydrogen atoms are not at 180 degrees from each other, but are unsymmetrically located on the oxygen atom as a result of the shapes of the electron orbitals that are involved in the bonding, which gets into quantum mechanics, and I will spare you that! Anyway, this is the reason why a water molecule has a dipole moment.)
O.K., here's the point of giving you all this gobbledygook:
Hydroxocobalamin, when it enters the blood plasma, mostly becomes aquacobalamin by picking up a hydrogen ion from the plasma. That is, instead of hydroxide being bound to the cobalamin, there will now be a complete water molecule bound to it. (This occurs because there's a chemical equilibrium established between aquacobalamin and hydroxocobalamin. The so-called "pKa" value for aquacobalamin is 7.8 while the pH of the blood is normally about 7.4 . This means that the equilibrium will be shifted toward formation of aquacobalamin.) But the hydrogen ion brings with it a positive charge, and that causes the aquacobalamin molecule to have a net positive charge, because hydroxocobalamin is a neutral molecule. So now you can probably see where I'm going with this. When hydroxocobalamin is used as the B12 supplement, we are really dealing in the blood primarily with aquacobalamin, a charged molecule, and charged molecules don't diffuse readily through cell membranes. So I suggest that that's why hydroxocobalamin supplementation doesn't work for Freddd or for others who are depending on direct delivery of the B12 coenzymes to their cells.
Now, why does hydroxocobalamin work for the other people? Well, I suggest that they are able to utilize normal transcobalamin delivery and normal processing of B12 inside their cells. They put hydroxocobalamin into their blood via the sublingual route. It rapidly converts mostly to aquacobalamin. However, transcobalamin will bind to all the forms of cobalamin, and it is therefore able to carry the aquacobalamin into the cells, where it then undergoes normal processing to form methycobalamin and adenosylcobalamin for use by the cells.
You might ask why it's necessary for this latter group to put the hydroxocobalamin into their bodies by the sublingual route, rather than just taking it orally. I think the answer to this question is that the absorption from the gut (using intrinsic factor) has a limited capacity, and the amount of B12 that is needed in ME/CFS or autism to overcome the hijacking by toxins in the absence of sufficient protection by glutathione (because it is depleted) is much greater than can be put into the blood by the intrinsic factor mechanism.
I think this can explain this seeming paradox that has bedeviled us (or me, at least!) for such a long time.
Best regards,
Rich