Supplement
Poly-γ-glutamic acid is a sticky, water-holding chain of glutamic acid made by bacteria, best known from fermented soybean natto, and it binds minerals such as calcium. Lab experiments found it scavenged free radicals and protected intestinal cells from oxidative damage, and in mice it shifted gut bacteria toward beneficial Lactobacillales, though the evidence is very limited. Nearly all of this came from cells and animals, so what it does in people remains unclear.
Sources: PMID 32165198; PMID 27974732
- Updated
- How we grade
- 11 studies cited
- Best evidence
- Grade D
- Conditions studied
- 2
- Outcomes
- 7
- Graded outcomes
- 0007
Evidence by condition
- Strong
- Moderate
- Limited
- Very limited
General
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Immune Function In preclinical studies, γ-PGA enhanced dendritic cell activation via TLR4 stimulation and dramatically inhibited tumor growth in tumor-bearing mice. As a vaccine adjuvant complexed with alum, it enhanced antigen delivery to lymph nodes and cross-protective immunity against H1N1 and H3N2 influenza strains in mice. A nanoparticle formulation with chitosan promoted pro-inflammatory cytokine production and T cell proliferation in vitro. | Improves (the measure goes up) | Moderate effect | 5 studies | |||
Studies that measured immune function
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| Probiotic Viability In vitro studies showed γ-PGA at 2.5% concentration significantly enhanced Bifidobacteria survival in fruit juices and protected bacteria in simulated gastric juice (pH 2.0) with less than 0.47 log CFU/ml reduction after 4 hours, versus free cell death within 2 hours. A separate study demonstrated γ-PGA with sodium alginate effectively protected Bifidobacterium species during freeze-drying. | Improves (the measure goes up) | Moderate effect | 4 studies | |||
Studies that measured probiotic viability
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| Gut Microbiota Composition In a murine model, oral γ-PGA administration increased the abundance of beneficial Lactobacillales while reducing Clostridiales in the gut, demonstrating prebiotic potential through 16S rRNA gene sequencing analysis. | Improves (the measure goes up) | Small effect | 3 studies | |||
Studies that measured gut microbiota composition | ||||||
| Glutamate and GABA Levels In a study of 60 Sprague-Dawley rats, γ-PGA elevated serum glutamate and GABA concentrations in normal-weight rats, and increased brain glutamate across both normal and high-fat diet groups. Effects were diminished in diet-induced obese animals, suggesting metabolic status influences efficacy. | Improves (the measure goes up) | Small effect | 3 studies | |||
| Gastrointestinal Protection In vitro cell-based assays showed γ-PGA provided complete cytoprotective effects against oxidative damage in Caco-2 intestinal epithelial cells, suggesting potential gastrointestinal mucosal protection. These effects remained stable through simulated gastrointestinal digestion conditions. | Improves (the measure goes up) | Small effect | 3 studies | |||
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Antioxidant Status In an in vitro study, γ-PGA demonstrated 85.2% hydroxyl radical scavenging at 1 mg/mL, 94.1% superoxide anion radical scavenging, and 96.0% lipid peroxidation inhibition. It showed complete protective effects in Caco-2 intestinal cells against oxidative damage, with antioxidant capacity remaining stable through simulated digestion. | Improves (the measure goes up) | Small effect | 3 studies | |||
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Bone Health In 75 aged laying hens, dietary supplementation with γ-PGA combined with nanosized zinc oxide increased eggshell thickness and elevated serum mineral concentrations compared to conventional supplementation. Separately, the compound's known calcium-binding properties suggest potential for enhancing calcium absorption, though direct human evidence is lacking. | Improves (the measure goes up) | Small effect | 3 studies | |||
Key findings
- Immune FunctionImproves (the measure goes up)
- Probiotic ViabilityImproves (the measure goes up)
- Antioxidant StatusImproves (the measure goes up)
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- Grade D
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Studies cited
11 studies from PubMed
- Antioxidant and gastrointestinal cytoprotective effect of edible polypeptide poly-γ-glutamic acid
- Optimized production of poly(γ-glutamic acid) (γ-PGA) using Bacillus licheniformis and its application as cryoprotectant for probiotics
- Poly-γ-Glutamic Acid Complexed With Alum Induces Cross-Protective Immunity of Pandemic H1N1 Vaccine
- Chitosan/poly(γ-glutamic acid) nanoparticles incorporating IFN-γ for immune response modulation in the context of colorectal cancer
- Prebiotic Effects of Poly-Gamma-Glutamate on Bacterial Flora in Murine Gut
- Effects of nanosized zinc oxide and γ-polyglutamic acid on eggshell quality and serum parameters of aged laying hens
- Poly(γ-glutamic acid), coagulation? Anticoagulation?
- Infection-mimicking poly(γ-glutamic acid) as adjuvant material for effective anti-tumor immune response
- Improving survival of probiotic bacteria using bacterial poly-γ-glutamic acid
- Poly-γ-glutamic acid: production, properties and applications
- Effects of poly-gamma-glutamic acid on serum and brain concentrations of glutamate and GABA in diet-induced obese rats