Holotranscobalamin is only 10-30%...

[PeterPositive]

Just found this simple graph showing the small slice of B12 that is really biologically active versus the rest floating in the serum and unusable.

Source

Interesting, isn't it?

If we add partial methylation blocks, transport and conversion issues etc... I can see why people here (myself included) need B12 by the bucketload to get going.

 

[misskatniss]

Yeah, and why a normal B12 level in the blood says NOTHING about the bioavailable amount! And no doc told me that which is even worse.

 

[PeterPositive]

Indeed that's pretty telling of the relevance of serum B12 values...