Cyanocobalamin is converted to hydroxocobalamin in the body.
Cyanocobalamin is
not converted to
hydroxocobalamin. However hydroxocobalamin converts to
methylcobalamin (Active form). There is a reason why hydroxocobalamin was used in Vimmortal (I'd imagine if Longecity worked on the formulation) and not cyanocobalamin nor methylcobalamin.
Only hydroxocobalamin converts to methylcobalamin – seamlessly, locally as needed and used up within seconds. Local needs safely determine the speed of methylcobalamin synthesis. This protects the body from systemic effects as described below while providing all the benefits. Hydroxocobalamin is also the most stable form of vitamin B12.(1,2) Hydroxocobalamin is also easily converted to adenosylcobalamin, a form of B12 preferred by mitochondria, while methyl B12 is not cross converted. (3)
Risks of methylcobalamin Non-enzymatic Methylation of Mercury“An early study of the biochemistry of microbial methylation of mercury involved the use of a cell extract of a methanogenic culture in the presence of low concentrations of Hg++. This extract caused the formation of (CH3)2Hg but had little methane through preferential interaction between methylcobalamin and Hg++. (4) Although the production of methylcobalamin in this instance depended on enzymatic catalysis, the production of (CH3)2Hg from the reaction of Hg++ with methylcobalamin did not. Simply put, without any other external influence, methylcobalamin can precipitate the formation of methylmercury in the body.
This nonenzymatic nature of mercury methylation by methylcobalamin has been confirmed by several scientists. (5,6). DeSimone explained this nonenzymatic mechanism of mercury methylation by methylcobalamin more than 25 years ago: (7) Hg +methylB12 → (CH3)2Hg+ (note added: hydroxocobalamin does not do this) According to Wood (8) the initial methylation of Hg++ in this reaction sequence proceeds 6000 times as fast as the second. However, more recent research has indicated that the methylation of methylmercury can proceed as fast as the initial methylation of mercury. (9,10) The methylation rate of methylmercury is affected by the counter ion associated with mercury. The rate is faster if sulfate is the counter ion than when it is a halogen ion such as chloride or iodide. (The halogens have a tendency to bind covalently to Hg++.)
Hydroxocobalamin has a half-life of days and is converted locally to methylcobalamin as needed. This longer retention and the higher blood levels achieved after hydroxycobalamin have been attributed to formation of stronger bonds formed by hydroxocobalamin.(11) Methylcobalamin has a very short half-life, measurable in minutes to hours.
1 Martindale:The Extra Pharmacopoeia, 30th Ed.,1993, 1055-1058
2 Linnell, J.C. et al. "Therapeutic Misuse of Cyanocobalamin". Lancet, November 11, 1978; pg
1053-1054.
3 Wayne A. Fenton and Leon E. Rosenberg Mitochondrial metabolism of hydroxocobalamin:
Synthesis of adenosylcobalamin by intact rat liver mitochondria
Archives of Biochemistry and Biophysics, 1978; 189(2): 441-447
4 Wood JM, Kennedy FS, Rosen CG.Synthesis of methyl-mercury compounds by extracts of a
methanogenic bacterium.Nature. 1968 Oct 12;220(5163):173-4.
5 Bertilsson L, Neujahr HY. Methylation of mercury compounds by methylcobalamin.
Biochemistry. 1971 Jul 6;10(14):2805-8.
6 Imura N, Sukegawa E, Pan SK, Nagao K, Kim JY, Kwan T, Ukita T. Chemical methylation of
inorganic mercury with methylcobalamin, a vitamin B12 analog.Science. 1971 Jun
18;172(989):1248-9.
7 DeSimone RE, Penley MW, Charbonneau L, Smith SG, Wood JM, Hill HA, Pratt JM, Ridsdale
S, Williams RJ. The kinetics and mechanism of cobalamin-dependent methyl and ethyl transfer to
mercuric ion.Biochim Biophys Acta. 1973 May 28;304(3):851-63.
8 Wood JM Biological cycles for toxic elements in the environment. Science 1974;183(129):1049-
52
9 Baldi F, Pepi M, Filippelli M. Methylmercury Resistance in Desulfovibrio desulfuricans Strains in
Relation to Methylmercury Degradation Appl Environ Microbiol. 1993 Aug;59(8):2479-85.
10 Baldi F. Microbial transformation of mercury species and their importance in the
biogeochemical cycle of mercury. Met Ions Biol Syst. 1997;34:213-57.
11 . Kohli RK, Nath A. .Significance of isomerization in hydroxocobalamin. Biochem Biophys Res
Commun. 1984 Dec 14;125(2):698-703
Further reading on hydroxocobalamin benefits:• Elian KM, Hoffer LJ. Hydroxocobalamin reduces hyperhomocysteinemia in end-stage
renal disease. Metabolism. 2002 Jul; 51(7):881-886
• Hoffer LJ, Elian KM. Parenteral vitamin B12 therapy of hyperhomocysteinemia in endstage
renal disease. Clin Invest Med. 2004 Feb;27(1):10-13.
• den Heijer M, Brouwer IA, Bos GM, Blom HJ, van der Put NM, Spaans AP, Rosendaal
FR, Thomas CM, Haak HL, Wijermans PW, Gerrits WB. Vitamin supplementation
reduces blood homocysteine levels: a controlled trial in patients with venous thrombosis
and healthy volunteers. Arterioscler Thromb Vasc Biol. 1998 Mar;18(3):356-361.
• Ogier de Baulny H, Gérard M, Saudubray JM, Zittoun J. Remethylation defects:
Guidelines for clinical diagnosis and treatment. Eur J Pediatr. 1998 Apr;15 7 Suppl
2:S77-S83.
• Bertoglio K, James S, Daprey L, Norman B, Hendren R. Pilot Study of the Effect of
MethylB12 treatment on Behavioral and Biomarker Measures in Children with Autism,
JACM, 2010, 16(5): 555-560.
Edited by JChief, 11 December 2011 - 11:03 PM.