Re: AndyCutler on B12 & Hg Methylation; and.Cyanocobalamin

[Guest guest]

Jo,

In a recent post you quoted Andy Cutler as saying the following:

" Ummm... errrr.... brain trying to think of polite

way to say this....

sizzle, sizzle, sizzle, overload.....

" Cyanocobalamin and all other forms of vitamin B-12

have their

desirable effects by being converted to

methylcobablamin.

Methylcobablamin is the ONLY active form of vitamin

B-12, and your

body makes it from all the other forms you eat. "

When he says " methylcobablamin, " I'm sure he means methylcobalamin.

Although what I'm about to discuss may not affect reactions involving

mercury, I think it should be pointed out that methylcobalamin is not

in fact the only active form of vitamin B12 in the human body. The

other known active form is 5'-deoxyadenosylcobalamin, or simply

adenosylcobalamin for short. This form of vitamin B12 is a cofactor

in the methylmalonyl-CoA mutase reaction, which converts

methylmalonyl-CoA to succinyl-CoA. This reaction is important in the

metabolism of the branched-chain amino acids isoleucine and valine, as

well as methionine, threonine, thymine and the odd-chain fatty acids.

It produces succinyl-CoA, which can be metabolized in the Krebs cycle

to produce energy and is also involved in the synthesis of fatty

acids. Methylmalonic acid is elevated in the blood serum and the

urine in those with vitamin B12 deficiency, and this serves the basis

for a test of vitamin B12 deficiency that is particularly relevant to

preventing the neurological effects of such a deficiency.

Adenosylcobalamin was actually the first coenzymatically active form

of vitamin B12 discovered (by H.A. Barker in 1964). It is discussed

in textbooks of biochemistry, including Harper's Biochemistry, 25th

Edition (2000), p. 635, ; Textbook of Biochemistry, Fourth Edition,

M. Devlin, Editor (1997), p. 1125; and Biochemistry, Third

Edition, by s, van Holde, and Ahern (2000), p. 738.

Andy correctly pointed out the importance of studying complete

scientific papers rather than relying only on abstracts. As I

mentioned, I intend to try to get a complete copy of the guinea pig

paper on my next trip to the medical library.

I am continuing to read Andy's book, and am finding it very

interesting, though I sometimes have difficulty determining which

statements have been established based on peer-reviewed research

papers and which are opinions. I think both are interesting and

useful, but I would find it helpful to know which are which, since

none of us, no matter how well-meaning we are, are correct in all of

our opinions. That's certainly true of my own opinions, sorry to say.

Thanks for relaying Andy's thoughts on B12 and mercury, and please

give him my regards.

Rich

[Guest guest]

Rich

Thank you for generously taking the time to explain the B12

conversions...appreciate seeing reasons for analysis rather than just

conclusions.

Your comments in full added perspective.

Best

Jo