RELATION OF SHORT-TERM PYRIDOXINE-HCL SUPPLEMENTATION TO PLASMA VITAMIN-B6 VITAMERS AND AMINO-ACID-CONCENTRATIONS IN YOUNG-WOMEN

Pyridoxal 5'-phosphate (PLP) is a coenzyme in many metabolic transformations of amino acids and may play a role in their absorption and transport. This investigation analyzed the effects of large oral doses (27 mg/d) of pyridoxine (PN)-HCl over 2 wk on plasma PLP and amino acid concentrations in 10 young women. Plasma PLP was 45 +/- 2 nmol/L (xBAR +/- SE) initially and reached 377 +/- 12 nmol/L after 7 d of supplementation. A steady-state PLP concentration remained as long as daily PN-HCl supplementation was continued. Plasma glutamic acid concentration was significantly lower after 7 and 14 d of supplementation whereas alpha-amino-N-butyric acid, alanine, cysteine, arginine, phosphoserine, and urea concentrations were significantly higher, particularly alpha-amino-N-butyric acid and cysteine. Altered plasma amino acid profiles and increased plasma urea concentrations in response to supplementation suggested accelerated protein and/or amino acid metabolism.