Methyl B12 from foods?

[Ninan]

Can methyl B12 be obtained from any foods? Like liver?

 

[mgk]

I've always been curious about this too but could never get a straight answer. I did a little more digging today and stumbled on a paper from the '70s which says that most of the B12 found in the diet is actually in the form of adenosylcobalamin:

Deoxyadenosylcobalamin (coenzyme B12) is the predominant vitamin B12 analogue present in a normal diet, although small amounts of other analogues such as methylcobalamin and hydroxocobalamin are found (Weissbach, Toohey, and Barker, 1959; Toohey and Barker, 1961; Lindstrand, 1964). Some hydroxocobalamin may arise as the result of photolysis of the coenzyme forms.

Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1176261/

 

[mgk]

I just found an even more detailed paper on it which gives relative amounts of each form. "o" means none detected, and the more "+", the more there is. Not exact but should give you a rough idea.

Interesting point:

Methylcobalamin was most prominent in egg yolk and in cheese and cheese products, and the higher proportion of methylcobalamin in cheese when compared to that found in milk suggested that there may have been biosynthesis of methylcobalamin by the bacteria utilized in the manufacture of cheese.

There's a bunch more information on absorption and such in the full paper. I highly recommend checking it out if you're in to that sort of thing.

You can get a PDF of it here: http://journals.cambridge.org/actio...ge=online&aid=838812&fileId=S0007114576000147

 

[Ninan]

Thanks a lot, @mgk ! I read the article, very informative. Glad liver was in there since I don't tolerate eggs or milk at the moment.