Vitamin B6 and Red Blood Cells

GAINESVILLE, Fla.Marginal vitamin B6 deficiency tended to decrease mean red blood cell (RBC) glutathione synthesis with no effect on RBC glutathione concentration, with a varied response (Am J Clin Nutr.2009;90(2):336-343). Glutathione plays various protective roles in the human body. Vitamin B6 as pyridoxal-5'-phosphate (PLP) is required as the coenzyme in the formation of glutathione precursors. Despite this obligatory role of PLP, previous studies showed vitamin B6 deficiency caused elevated glutathione concentrations in rat liver and human plasma. Researchers measured plasma and RBC glutathione concentrations and the fractional and absolute synthesis rates of RBC glutathione in 13 healthy volunteers aged 21 to 39 years.
Dietary vitamin B6 restriction did not significantly affect the glutathione concentration in plasma or RBCs. Because the cysteine concentration in plasma and RBC did not change during vitamin B-6 restriction, researchers concluded the effects of marginal vitamin B-6 deficiency on glutathione synthesis are not caused by altered precursor concentrations.