Nutr Res Pract.  2024 Oct;18(5):663-673. 10.4162/nrp.2024.18.5.663.

Consumption of poly-γ-glutamate- vitamin B6 supplement and urinary microbiota profiles in Korean healthy adults: a randomized, double-blinded, placebo-controlled intervention study

• Park J
• Baik I

• KMID: 2560051
• DOI: http://doi.org/10.4162/nrp.2024.18.5.663

Abstract

BACKGROUND/OBJECTIVES
Poly-γ-glutamic acid (γ-PGA), a natural polymer found in fermented soybean products, has been reported to play a prebiotic role in the gut. This intervention study investigated the effects of γ-PGA-containing supplement consumption on urinary microbiota in healthy adults because of limited data on such investigation.
SUBJECTS/METHODS
A 4-week parallel trial including 39 male and female Korean adults, who were free of chronic diseases and infection, was designed as a randomized, doubleblinded, placebo-controlled study. A total of 30 participants completed the study wherein the intervention group (n = 17) received a mixture supplement containing 600 mg/day of γ-PGA and 100 mg/day of vitamin B6, while the control group (n = 13) received a placebo. Paired datasets (baseline and endpoint data) of microbiota profiles, which were constructed via urinary assays of microbe-derived extracellular vesicles, were analyzed and compared between the two groups.
RESULTS
Only the intervention group yielded significant results for the Bray-Curtis and Jaccard dissimilarity indices between baseline and endpoint data (P < 0.05). In the phylumlevel analysis of microbial composition, the Firmicutes to Bacteroidetes ratio (FB ratio) tended to decrease from baseline in the intervention group; however, it increased in the control group. Differences between the baseline and endpoint FB ratios were significant between the two groups (P < 0.05).
CONCLUSION
This study’s findings suggest that γ-PGA-vitamin B6 supplementation potentially alters the microbial community composition of a host. Further investigation into the biological consequences of commensal microbiota alteration by γ-PGA-containing supplement consumption is warranted.

Keyword

Poly-gamma-glutamic acid; microbiota; urine; clinical trial

Figure

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  Fig. 1 Number of participants who were enrolled in, withdrew from, and completed the randomized, double–blinded, placebo–controlled intervention study. The intervention group received poly–γ–glutamate and vitamin B6 mixture supplementation, whereas the control group was administered a placebo.

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  Fig. 2 Principal coordinate analysis of the β-diversity indices in the control and intervention groups. The scatter plots represent principal coordinate 1 (Axis 1) vs. principal coordinate 2 (Axis 2), with variations explained by the components indicated. Samples are indicated by points and colored according to baseline (red) and endpoint (blue) data. The results of the β-diversity indices, namely, the Bray-Curtis (A) and Jaccard (B) indices for the control group as well as those of the Bray-Curtis (C) and Jaccard (D) indices for the intervention group are presented.

• 

  Fig. 3 Baseline and endpoint phylum-level microbial composition profiles of the control (A) and intervention (B) groups. The results of a bar represent phylum–level microbial composition profiles for each participant.

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