Vitamin B12 | Methylcobalamin
Vitamin B12, or cobalamin, is unique among vitamins because it contains a metal ion, cobalt, from which the term cobalamin derived. Methylcobalamin is one of the two coenzyme forms of vitamin B12 (the other is adenosylcobalamin). These are the forms used in enzymes in the human body. Methylcobalamin is used in only one enzyme, methionine synthase, which is required to make the purines and pyrimidines needed for DNA. Methionine synthase also links the folate cycle and the S-adenosylmethionine cycle, converting methyltetrahydrofolate into tetrahydrofolate, and subsequently homocysteine into methionine (this acts to support healthy homocysteine levels). Methylcobalamin is a central player in a process called methylation or methyl donation. This process has widespread interactions with metabolic function. As an example, methylation is one of the main ways the expression of genes is changed to match our genes to diet, lifestyle and environment.
Vitamin B12 can be found in different forms, including cyanocobalamin, hydroxycobalamin, adenosylcobalamin, and methylcobalamin. Adenosylcobalamin and methylcobalamin are considered to be the coenzyme forms, because they are what’s used in enzymes in the body.
The methylcobalamin form is selected when a biologically active form of vitamin B12 is desired and the formulation’s goal is to support methionine synthase, one of the two enzymes in the body that uses vitamin B12.
Methylcobalamin sourcing is focused on ensuring it is non-GMO, gluten-free and vegan.
Methylcobalamin is dose-dependent (see Neurohacker Dosing Principles) in the range it’s commonly dosed (up to about 1 mg), with higher doses doing a better job in normalizing functional markers of vitamin B12 status than lower doses. The RDA for vitamin B12 is very low. Vitamin B12 function is not always maintained at these low levels, with functional status sometimes requiring substantially higher doses to normalize. Relative insufficiencies are more common with older age and in persons eating a vegetarian or vegan diet (vitamin B12 is found in animal products but not plants).
Methionine Synthase Activity
Cardiovascular and cerebrovascular function
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