Possible Interaction: 3-Hydroxykynurenine and Vitamin B 6

“In all participants, serum Trp was positively associated with plasma pyridoxal 5'-phosphate (PLP; r = 0.28, P < 0.0001), reaching a plateau at PLP concentrations of ∼83 nmol/L. HK was inversely associated with PLP (r = -0.14, P < 0.01).”

“Users of vitamin B-6 supplements (n = 671) had 6% lower concentrations of HK than nonusers (n = 1765; P = 0.0006).”

“A segmented relationship was observed between PLP and HK , with a steep slope at PLP concentrations < 18.4 nmol/L, corresponding to the 5th percentile, and an almost zero slope at higher PLP concentrations.”

“Oral supplementation with pyridoxine hydrochloride (40 mg/d) for 1 mo increased plasma PLP 8-fold, reduced the geometric mean (95% CI) of HK from 29.5 to 20.2 nmol/L (P < 0.001), and abolished the steep segment of the PLP-HK curve.”

“ Pyridoxine supplementation partially corrected the inhibition especially that of 3-hydroxykynurenine transaminase enzyme.”