What you need to know about polyglutamic acid.

The polyglutamic acid is a biopolymer derived from the amino acid glutamic acid. This compound was first isolated from a marine jellyfish. It helps the animal store water in its tissues, preventing rapid dehydration from ocean salt. Polyglutamic acid also occurs in the mucilage of natto, a traditional Japanese food with a sticky, paste-like texture produced by fermenting soybeans. Formerly used to accelerate wound healing, the polyglutamic acid is known for its hydrating properties. It is listed under the INCI name “Polyglutamic Acid.” In a formula for the skin, polyglutamic acid is used at concentrations between 0.1% and 3%.

Polyglutamic acid is a biotechnological molecule derived exclusively from microbial fermentation.

Its production relies on the activity of certain Gram-positive bacteria of the class Bacilli, naturally present in soil or on plant surfaces. Among the most commonly used for this process are Bacillus subtilis and Bacillus licheniformis. Thanks to this fermentation technology, polyglutamic acid can be produced at scale under environmentally friendly conditions and with a high degree of purity. One particular aspect of polyglutamic acid production is that it does not occur via the ribosomal pathway. Unlike most peptides produced by ribosomes reading messenger RNA to assemble amino acids, polyglutamic acid is formed via through a non-ribosomal mechanism. This type of synthesis involves a set of specialized enzymes able to assemble amino acids directly into a long polymeric chain. Non-ribosomal production is found only in certain microorganisms, such as bacteria and fungi.

Serums, face masks, targeted eye treatments contain polyglutamic acid, a versatile active ingredient in skin care. Its popularity stems from the different benefits of the polyglutamic acid for the skin.

• Polyglutamic acid is known for its hydrating properties.

  Polyglutamic acid is primarily used as a moisturizing agent in cosmetics. It can form a microgel—a film on the skin’s surface that swells and traps water molecules, enhancing water retention in the epidermis. Polyglutamic acid can thus hold up to 5,000 times its weight in water. Studies show it stimulates production of lactic acid, urocanic acid, and pyrrolidone carboxylic acid—molecules that form the skin’s natural moisturizing factor. Located in the stratum corneum, this complex of hygroscopic compounds maintains skin hydration. Polyglutamic acid reduces synthesis of hyaluronidase, the enzyme that degrades hyaluronic acid in the dermis.

Polyglutamic acid’s multiple actions make it an ally for dehydrated skin.

• Polyglutamic acid may help reduce signs of aging.

  In addition to its moisturizing properties, relevant for preventing and reducing dehydration lines, polyglutamic acid may have a broader effect on skin laxity. A study in vitro showed that this active ingredient could increase the expression of the genes col1a1a and col1a1b, associated with collagen production, and the genes eln1 and eln2, linked to elastin synthesis. For reference, collagen and elastin are structural proteins of the dermal extracellular matrix that play a key role in skin suppleness and elasticity. These initial findings must be confirmed in clinical studies before stating that polyglutamic acid affects skin aging.

• Polyglutamic acid has wound-healing properties.

  Polyglutamic acid is recognized for its effects on wound healing and cell regeneration. It stimulates local production of the growth factor TGF-β and β-catenin, two molecules involved in cell proliferation, collagen synthesis, and angiogenesis. Polyglutamic acid could accelerate the healing of minor wounds or promote rapid fading of post-acne marks (post-inflammatory hyperpigmentation and post-inflammatory erythema). Studies should be conducted in this area to verify this hypothesis in the coming years.

• Polyglutamic acid may soothe redness and itching.

  Polyglutamic acid may soothe sensitive skin and reduce redness and itching linked to inflammation. Preclinical studies showed that this ingredient reduced the expression of vascular endothelial growth factor A (VEGF-A) and its receptor VEGFR2. These molecules support inflammation-related angiogenesis. By lowering these mediators, polyglutamic acid helps limit blood vessel overgrowth and vascular permeability. Clinical trials are needed to confirm this effect, but polyglutamic acid might reduce the redness and swelling seen in inflammatory conditions.

Even if it is less common, the polyglutamic acid can also be used to support hair care. Indeed, its properties outlined above apply to the scalp, which also needs regular hydration and soothing to stay healthy. Regarding lengths, some evidence suggests polyglutamic acid may benefit strands. Exposed to mechanical, thermal, and chemical stressors, strands can lose shine and weaken, eventually forming split ends that cannot be salvaged. Polyglutamic acid's film-forming properties create a protective layer that complements the hydrolipidic film on the hair surface. This action may help limit the hair porosity, better protect the fiber against external factors, and in the end to maintain supple, resilient hair.

Note that no clinical studies exist to confirm the benefits of polyglutamic acid for hair.

Polyglutamic acid exhibits high skin tolerance.

This ingredient does not irritate or sensitize skin and does not trigger inflammatory reactions. Its tolerance reflects its high molecular weight and polymeric structure, which limit skin penetration. The safety of polyglutamic acid was assessed in several studies, including patch tests on volunteers who applied the ingredient under occlusion for 24 to 48 hours. The results showed no reaction: no erythema, edema, or pruritus were observed. In addition, analyses in vitro demonstrated no genotoxicity, meaning polyglutamic acid does not cause mutations or DNA damage. It is suitable for daily use and no contraindications prevent its use during pregnancy or breastfeeding.

• SONA H.-J. & al. In vitro evaluation of new functional properties of poly-γ-glutamic acid produced by Bacillus subtilis. Saudi Journal of Biological Sciences (2014).

• RADECKA I. & al. Poly-γ-glutamic acid: production, properties and applications. Microbiology Society (2015).

• SUNG M.-H. & al. Promotion effects of ultra-high molecular weight poly-γ-glutamic acid on wound healing. Journal of Microbiology and Biotechnology (2015).

• NAJAR N. & al. Poly-glutamic acid (PGA) - Structure, synthesis, genomic organization and its application: a review. International Journal of Pharmaceutical Sciences and Research (2015).

• HIURA N. & al. Characterization of poly(L-glutamic acid)-grafted hyaluronan as a novel candidate medicine and biomedical device for intra-articular injection. Journal of Biomedical Materials Research (2017).

• YANG S.-A. & al. Gamma polyglutamic acid (gamma-pga, h form), gamma-polyglutamate hydrogels for use as super moisturizers in cosmetic and personal care products (2019).

• XIA T. & al. Cucumber (Cucumis sativus L.) with heterologous poly-γ-glutamic acid has skin moisturizing, whitening and anti-wrinkle effects. International Journal of Biological Macromolecules (2024).