Adequacy of vitamin B6 supplementation during pregnancy: a prospective study13

ABSTRACT This prospective study assesses the effect of 2.5, 4, and 10 mg of pyridoxine supplementation during pregnancy on maternal and fetal plasma levels of pyridoxal 5’-phosphate (PLP) and on the degree of coenzyme saturation (activation factor) of aspartate aminotransferase and alanine aminotransferase (aEGOT and aEGPT) in maternal erythrocytes. More than 4 mg of pyridoxine supplementation daily was required for most pregnancies to maintain maternal plasma PLP levels within the range observed during the first trimester and in the nonpregnant state. The plasma PLP concentrations in maternal and cord blood were highly correlated and indicated a dependence of fetal vitamin B, nutrition on maternal circulating PLP. Measurements of aEGOT and aEGPT were not as reproducible as plasma PLP assays and were less sensitive and quantitative indicators. In the majority of subjects, the changes in aEGOT and aEGPT with time correlated poorly with the changes in plasma PLP. However, when the data were analyzed without regard for their dependence on time, they demonstrated a negative, linear correlation between aEGOT and log plasma PLP and between aEGPT and log plasma PLP for the group on 2.5 mg of pyridoxine and for all the subjects combined. Finally, the dietary records showed that most of the subjects consumed less than 2 mg of vitamin B, daily from their food. The results indicate that the curren