Here are a few articles that might help with background. A general
summary , some info about
P5P, a
paper which better explains the detail of uptake and processing of B6 (you can ignore the later part about inborn errors of metabolism).
This latter paper doesn't canvas the direct uptake of P5P (ie without removal of phosphate ) which the first two mention. It certainly does occur. There is probably a better reference but couldn't lay my hand on it, but
here is one.
Finally there is a thread about B6
here. Some of the posts toward the end are relevant.
