Effects of poly-gamma-glutamic acid and vitamin B6 supplements on sleep status: a randomized intervention study

• Published in: Nutrition research and practice Vol. 15; no. 3; pp. 309 - 318
• Main Authors: García-García, Carolina, Baik, Inkyung
• Format: Journal Article
• Language: English
• Published: 한국영양학회 01.06.2021; The Korean Nutrition Society and the Korean Society of Community Nutrition
• Subjects: Original Research; 생활과학; sleep; vitamin B6; Functional food
• ISSN: 1976-1457; 2005-6168
• DOI: 10.4162/nrp.2021.15.3.309

BACKGROUD/OBJECTIVESData 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 B6 (VitB6) supplements improve sleep duration and quality. SUBJECTS/METHODSA 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. RESULTSSignificant 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. CONCLUSIONSOn 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 REGISTRATIONClinical Research Information Service Identifier: KCT0005083.