Nutr Res Pract.  2021 Jun;15(3):309-318. 10.4162/nrp.2021.15.3.309.

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

• García-García C
• Baik I

• KMID: 2516070
• DOI: http://doi.org/10.4162/nrp.2021.15.3.309

Abstract

BACKGROUD/OBJECTIVES: Data regarding the effects of poly-γ-glutamic acid (γ-PGA) on sleep status are limited. This study aimed to test whether γ-PGA and vitamin B 6 (VitB6) supplements improve sleep duration and quality.
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

Keyword

Functional food; vitamin B6; sleep

Figure

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  Fig. 1 Study flowchart.Group A received γ-PGA supplementation only; Group B received VitB6 supplementation only; Group C received both γ-PGA and VitB6 supplementation. The number of participants who were enrolled, dropped out, and completed the trial by interventions in the randomized, double-blinded, placebo-controlled, and crossover study.γ-PGA, poly-γ-glutamic acid; VitB6, vitamin B6.

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