Dog Person pointed out in another thread, that only dephosphorylated vitamins can enter tissues. I was surprised by this statement, as phosphorylated (activated, coenzyme) forms of vitamin B are touted as having higher bioavability. I found a source confirming this: "As only dephosphorylated vitamers can be transported into the cells (Coburn et al., 2003) the bioavailability of intact pyridoxal 5-phosphate upon oral intake would be low. Bioavailability of vitamin B6 from pyridoxal 5-phosphate requires hydrolysis of the phosphate group before absorption through the intestinal layer may occur." http://www.efsa.europa.eu/en/scdocs/doc/afc_ej760_pyridoxal_op_en,0.pdf So where does this leave coenzyme forms of vitamin B? Useless? And could someone tell me why the vitamins are phosphorylated in the liver, only to be dephosphorylated before entering cells?