Hyaluronic acid and polyglutamic acid face cream: What are its benefits?

Skin hydration depends mainly on the water bound to hyaluronic acid molecules in the dermis and in part of the epidermis. (2)

Hyaluronic acid:

• Can bind 1,000 times its volume in water: A highly hygroscopic molecule, hyaluronic acid helps hydrate both the stratum corneum and the dermis. As a humectant, it draws water from the dermis up to the epidermis.

• Hydrates the dermis: It helps regulate the skin’s water balance, osmotic pressure, and ionic flow, while acting as a selective filter that excludes certain molecules. It also contributes to stabilising skin structures.

• Hydrates the epidermis: Hyaluronic acid found in the basal layer plays a role in regulating the cell cycle. In the granular and spinous layers, it supports skin hydration by retaining water molecules from the dermis within the extracellular matrix.

• Locks in moisture within the hydrolipidic film: This natural surface emulsion of water and lipids helps retain moisture at the skin’s surface. The hydrolipidic film is essential for maintaining skin suppleness, as it holds the water bound by hyaluronic acid.

• Stabilises collagen and elastin fibres: Hyaluronic acid is found surrounding collagen and elastin fibres, helping to maintain their optimal structure. Over time, these connections weaken, leading to a loss of organisation in collagen and elastin fibres, which can contribute to the appearance of fine lines, wrinkles, and nasolabial folds. (1)

• Hydrates and supports cellular regeneration: Its high water-retention capacity helps slow the formation of wrinkles and improve the appearance of existing fine lines. This hydration also promotes cellular regeneration and helps stimulate collagen production.

• Helps regulate skin inflammation: In the event of tissue injury, hyaluronic acid is actively produced and plays a key role in regulating tissue repair. It helps modulate the body’s innate response to damage and supports the activity of epithelial cells and fibroblasts. (3)

• May help soothe inflammatory skin conditions: Numerous preclinical and clinical studies have explored the potential of hyaluronic acid to help relieve a wide range of inflammatory skin conditions, such as dry skin, rosacea, and skin erythema. (1)

The effectiveness of hyaluronic acid depends on its molecular weight: the lower the molecular weight, the greater the improvements in skin hydration, elasticity, and reduction of periocular wrinkles in women. (1)

• High molecular weight hyaluronic acid (between 50KDa and 3000KDa*) penetrates less easily through the different layers of the skin. It remains mainly on the surface, forming a thin, protective and essential hydrating film.

• Conversely, a lower molecular weight (20–300 kDa) can penetrate the stratum corneum, the epidermis, and deeper dermal layers.

It is therefore beneficial for cosmetic formulations to combine both molecular weights of hyaluronic acid.

* Da = Dalton, unit of measurement

• Binds effectively to water molecules: Its strong affinity for water and its ability to stimulate the skin’s Natural Moisturising Factor (NMF) give it intense hydrating properties.

• Boosts the production of moisturising factors: As a humectant, it helps increase the production of NMF components such as urocanic acid, pyrrolidone carboxylic acid, and others. These compounds, synthesised in the deeper layers of the stratum corneum, play a key role in maintaining skin health by supporting hydration and preventing excessive dryness. (5)

• Film-forming: When dissolved in water, polyglutamic acid molecules can self-assemble to form cohesive films on the skin. (4) This ability to retain moisture while creating a protective barrier provides intense hydration, enhanced protection, and a pleasant texture in cosmetic formulations.

• Protector of hyaluronic acid : Polyglutamic acid has been shown to improve skin elasticity more than collagen and hyaluronic acid (5). This is partly because γ-PGA is an inhibitor of hyaluronidase, an enzyme that breaks down hyaluronic acid in the skin's dermis. Its benefits are therefore easy to understand. 

• Improves skin texture : It stimulates collagen production and maintains its content in the skin over time.

Polyglutamic acid has been extensively studied in recent years. (4)

• It has been shown to promote cell growth in fibroblasts and keratinocytes, which is particularly beneficial for supporting wound healing.

• In addition, γ-PGA has shown a potentially significant photoprotective effect against UV-induced damage. However, to date, there are still limited studies on this topic.

As with hyaluronic acid, the impact of different molecular weights of polyglutamic acid is of growing interest in the cosmetics field. The molecular weight of PGA influences its effectiveness on the skin.

• Polyglutamic acid with a higher molecular weight tends to form a more occlusive barrier on the skin’s surface, helping to reduce transepidermal water loss while improving skin hydration by preventing moisture evaporation.

• Low molecular weight PGAs penetrate more deeply into the skin layers, where they can bind to water molecules and boost hydration from within.

The skin is one of the few organs that directly protects us from external aggressions. Constantly exposed to its environment, it is continuously challenged, and its components can become weakened over time. Hydrating the skin means nourishing and restoring it, helping to optimise its essential functions.

Moreover, the human body, including the skin which is its largest organ, is made up of over 80% water. When the skin is unable to retain sufficient moisture, it becomes dry. Common contributing factors include frequent bathing, harsh soaps, ageing, cold, wind, heat, UV exposure, and pollution.

Skin hydration prevents:

• skin aging

• dull complexion

• feelings of tightness

• dryness

The characteristic signs of dehydrated skin are as follows:  

• Dull complexion and lack of radiance

• Localised tightness

• A feeling of skin discomfort

• Shiny areas due to increased sebum secretion

• The appearance of dehydration lines not related to ageing (around the eyes, on the forehead, etc.)

• Increased sensitivity

• Appearance of redness when exposed to external aggressions.

This formula combines two types of hyaluronic acid with different molecular weights, covering a broad spectrum (<20 kDa to 3,000 kDa).

• Low molecular weight hyaluronic acids (Renew) <20 kDa help restore the skin barrier from within, reduce roughness and inflammation, and improve skin elasticity and firmness while delivering deep repair.

• High molecular weight hyaluronic acids (Relift), ranging from 50 kDa to 3,000 kDa, act on the skin’s surface to enhance firmness and elasticity, providing a lifting effect on fine lines and wrinkles.

Thanks to these two grades, the formula targets multiple biological pathways.

• Hydrate your skin from within by drinking enough water and eating water-rich foods such as fruits and vegetables

• Maintain good surface hydration by choosing humectants and hydrating ingredients that help retain moisture at the skin’s surface

• Strengthen your skin's natural barrier by incorporating ceramides and plant oils into your routine by adding ceramides and plant oils to your routine. 

For more information: Moisturise your skin naturally - Aroma-Zone