Effects of poly-gamma-glutamic acid and vitamin B 6 supplements on sleep status: a randomized intervention study

ABSTRACT

SUBJECTS/METHODS@#A factorial randomized, double-blinded, placebo-controlled crossover study included 47 adults (25 men and 22 women) who were free of chronic disease.Stratified randomized allocation considered age and gender for three interventions, group A (supplementation with γ-PGA 600 mg; n = 16), group B (supplementation with VitB6 100 mg; n = 14), and group C (dual supplementation of both γ-PGA 600 mg and VitB6 100 mg;n = 17). Participants underwent a 1-mon intervention period, followed by a 1-mon washout period, and then a second 1-mon intervention period. Differences (mean ± SD) in nighttime sleep status before and after supplementation were compared between the placebo and intervention groups using nonparametric tests. @*RESULTS@#Significant changes in sleep duration (0.27 ± 0.98 h, P < 0.05) and the Pittsburgh Sleep Quality Index global score (−0.52 ± 1.58, P < 0.05) indicating improved sleep status were observed in the intervention compared with the placebo of group C while no significant changes were observed in groups A and B. No statistical significance was detected between the intervention and the placebo; however, there was a greater increase in the group C intervention (4.59 ± 38.5 ng/mL) in serum serotonin concentrations than the groups A and B interventions. No side effects were observed. @*CONCLUSIONS@#On the basis of these findings, the dual supplementation of γ-PGA and VitB6 may be effective as functional food components to improve nighttime sleep status.Trial Registration Clinical Research Information Service Identifier KCT0005083