Forrest W. Thye

Plasma B6 vitamer and 4-pyridoxic acid concentrations of men fed controlled diets

A rapid and sensitive procedure is described for the analysis of all the B6 vitamers and 4-pyridoxic acid in human plasma utilizing reversed-phase high-performance liquid chromatography with ultraviolet and fluorometric detection. Pyridoxal phosphate values obtained by radiometric and chromatographic, ultraviolet and fluorometric, assays were highly correlated as were pyridoxine phosphate values determined using both detectors. Plasma B6 vitamer and 4-pyridoxic acid concentrations of 22 men fed diets containing 0.75-0.98 mg of vitamin B6 daily for eight weeks were in the range of reported values; pyridoxal phosphate was their predominant plasma B6 vitamer. This methodology should be useful in the assessment of vitamin B6 requirements.