I am confused about Methylcobalamin and it’s conversion

[Freezeframe]

I am taking Methylcobalamin and supplementing with adenosylcobalamin . I keep reading that Methylcobalamin converts into adenosylcobalamin but I also see lots of posts that say it doesn’t . Any thoughts ?

[fbirder]

The ones that say that methylcobalamin cannot be converted to adenosylcobalamin are totally and utterly wrong.

All forms of B12 that people normally take (methylcobalamin, hydroxocobalamin, cyanocobalamin and adenosylcobalamin) are all converted to something called cob(II)alamin as soon as they enter the cell. From that point onwards, all forms are equivalent. ncbi.nlm.nih.gov/pubmed/258...

Here it is described in pictures ncbi.nlm.nih.gov/pmc/articl...

[Gambit62 Administrator]

Freezeframe - there have been a few reported cases of people with a specific genetic problem that meant they weren't able to convert methyl to adenosyl but it is extremely rare in the sense that there are only a couple of reported cases.

[fbirder in reply to Gambit62]

People with such genetic defects are going to know if they have it. Symptoms tend to appear in infancy...

Clinically, patients have the following common features: failure to thrive, lethargy, vomiting of protein feeds, dehydration, respiratory distress and hypotonia

[Gambit62 Administrator in reply to fbirder]

fbirder, I'm not sure which gene or variant it is - there are a over a dozen genes that will affect the processing of B12. The report I remember, which I haven't actually book marked so probably no hope of getting back to it on pubmeds was related to someone who was being treated for a B12 absorption problem with just methylB12, so not necessarily the case that everything is picked up in infancy - particularly if a latent gene that needs other conditions to cause it to express.

[fbirder in reply to Gambit62]

The paper I was using specifically looks at the genes responsible for conversion of cob(II)alamin to adenosylcobalamin. ncbi.nlm.nih.gov/pmc/articl...

[Gambit62 Administrator in reply to fbirder]

thanks for sharing

interesting