Ingredient · High-Molecular-Weight Humectant
Polyglutamic Acid (γ-PGA)
INCI · Polyglutamic Acid
Related names and forms: γ-PGA · Poly-γ-Glutamic Acid · Natto Gum. This list does not indicate synonyms or exact ingredient matches.
Polyglutamic acid (γ-PGA or Polyglutamic Acid) is an interesting cosmetic ingredient originating in the biochemistry of Japanese natto, a fermented soybean food. The distinctive viscous, stringy texture of natto is the natural work of this high-molecular-weight polypeptide: glutamic acid chains produced by Bacillus subtilis natto during fermentation form PGA. This natural source explains its positioning in "bio-based" and "fermentation-derived" messaging, particularly in premium moisturising serums from Asian K-Beauty and J-Beauty brands. Its marketing story mostly rests on the claim that it "holds 5 times more water than hyaluronic acid". This is a theoretical capacity observed in some in vitro studies, but reliable data showing that the full difference translates clinically to topical skin application are limited. PGA products remain relatively few in the Turkish market, mostly in premium formulas from Asian brands. Klaris reads it as a complementary high-molecular-weight humectant working with HA, not an alternative that replaces it. Specifically vetted clinical dermatology research on PGA is limited; most information comes from formulation chemistry and in vitro testing.
i. Cosmetic Functions
Frequently Discussed Effects
The following headings summarise areas of effect frequently discussed in the literature; visible results in each area require regular use and a suitable formula.
A High-Molecular-Weight Film
It forms a moisture-retaining film on skin to support a feeling of surface hydration.
An Immediate Feeling of Moisture
Its high molecular weight creates a feeling of saturation immediately after application.
A Complement to HA
It frequently shares a formula with hyaluronic acid, offering a layered hydration strategy using two high-molecular-weight humectants.
Mechanism
What Happens Within the Skin?
The following points summarise mechanisms from dermocosmetic literature in plain English. Klaris presents them as background information to help readers understand the context, not as medical claims.
Step 1
A High-Molecular-Weight Film
PGA generally has a molecular weight of 500-2000 kDa, similar to HMW hyaluronic acid. It slows moisture loss by forming a physiological film on the skin surface.
Step 2
Hygroscopic Water Binding
Its many carboxyl groups provide strong hydrogen-bonding capacity and a theoretically high water-retention profile. The size of its topical effect depends on formula context.
Step 3
NMF Production Support Signals
Some in vitro studies suggest PGA may support natural production signals for NMF components such as sodium PCA, urea and amino acids in the stratum corneum.
Step 4
Synergy with Hyaluronic Acid
When PGA and hyaluronic acid are formulated together, their two different polymer film structures overlap, forming part of the modern "multi-MW humectant" approach.
ii. Role in the Formula
How Is It Read on a Label?
Polyglutamic acid is generally used at 0.1% - 2% in premium moisturising serums. Like hyaluronic acid, it has a high-molecular-weight polymer profile, a broad pH window (pH 4.0-8.0) and compatibility with most actives. It costs more than hyaluronic acid.
A Closer Look · pH, Stability, Synergy
PGA is convenient to formulate: water-soluble, stable at pH 4.0-8.0 and compatible with most actives. Concentrations are mostly 0.1% - 2%. Its high-molecular-weight polymer profile resembles hyaluronic acid; it works even at low levels, while levels above 2% may make the texture sticky or stringy. PGA costs substantially more than hyaluronic acid, the practical reason it mostly appears in premium products. It works with humectants such as hyaluronic acid, glycerin, sodium PCA and betaine and frequently appears in formulas using modern "multi-humectant" or "multi-MW" messaging. Compatibility in combined use cannot be guaranteed from ingredient names alone; the product formula and conditions of use must be considered together. A patch test may be useful for profiles with known allergy to soy- or natto-derived ingredients; as a fermentation-derived ingredient, it can receive rare allergy reports. There is no specific warning for topical PGA during pregnancy. It also appears in hair care, supporting moisture balance by forming a film on the hair shaft. For Klaris, its value lies in complementing a layered hydration strategy with hyaluronic acid, not in being a "revolutionary active".
Typical Concentration Range
0.1% - 2% (common in cosmetic formulas)
Ingredient Family
Humectants
iii. Sensitivity Advisory
A Note on Extra Care in Context
PGA is well tolerated by most skin profiles, with rare allergic reactions reported. A patch test may be useful with known sensitivity to soy or natto/fermentation products.
A sensitivity advisory is not an instruction for use; where individual health circumstances, pregnancy or known sensitivities are involved, discussing the decision with your doctor may be a more contextual approach.
Common Misconceptions
Frequently Confused Points
Common Belief
PGA holds 5 times more water than hyaluronic acid and replaces it.
A More Contextual Reading
High water-retention capacity can be observed in vitro, but reliable data showing that the full difference translates clinically to topical application are limited. Reading PGA as a complement to HA rather than a replacement is more consistent.
Common Belief
PGA is always safe and natural because it comes from natural natto.
A More Contextual Reading
Cosmetic PGA is fermentation-derived (Bacillus subtilis) and has a natural background, but rare allergic reactions can be reported. A patch test may be useful with known soy or natto sensitivity.
Common Belief
PGA penetrates beneath skin to create plumpness.
A More Contextual Reading
Its high molecular weight (500+ kDa) prevents PGA from crossing the skin barrier. It forms a surface film, providing superficial hydration and temporary plumpness. The same limitation as hyaluronic acid applies here.
Scientific Basis
Sources and Their Scope
The following headings indicate areas of research; they are not citations of a specific publication or confirmation that every statement on this page has been verified. The links provided should be read with their individual scope in mind.
- International INCI / CosIng Database
- Dermocosmetic Research Publications
- Formulation Chemistry Guides
Starting Points for Independent Research
These links lead to official databases and serve as starting points for searches.
v. Humectants Family
Other Ingredients in the Same Family
Explore ingredients in the same functional family to deepen your reading of formulas.
vi. Academy · Related Reading
For a Closer Look
Klaris · Example Analyses
How Does Polyglutamic Acid (γ-PGA) Feature
in Your Products?
Explore product examples to see the ingredient list, general assessment and match score that changes with the example profile together.
Masked products and example profiles, not a personal analysis. Profile matching in the app is part of Klaris Premium. The app is currently available in Turkish. An English version is in preparation.