Humectants in Skincare Science

Humectants: Hydration Heroes in Skincare and Beyond

Humectants are a vital class of compounds widely used in skincare, haircare, and various industrial applications for their moisture-retaining properties. These substances attract water from the environment and bind it to the surface of the skin or hair, keeping them hydrated. In this article, we'll explore the science behind humectants, how they work, the most common types, and their benefits and drawbacks, with scientific evidence and references.

What Are Humectants?

Humectants are hygroscopic compounds, meaning they attract and hold water molecules from the surrounding environment through hydrogen bonding. This process helps to keep skin, hair, or other surfaces moist and hydrated. They work by pulling moisture either from the air or the deeper layers of the skin (dermis) to the outermost layer (epidermis).

Humectants are commonly found in skincare products like moisturizers, serums, and cleansers. They also appear in hair care products, foods, pharmaceuticals, and industrial goods due to their ability to retain moisture.

How Do Humectants Work?

Humectants operate on the principle of osmosis, where water moves from areas of high concentration to low concentration. When applied topically, humectants bring water from the climate into the layer corneum (the skin's peripheral layer) assuming that the climate is damp. In dry circumstances, humectants pull dampness from more profound layers of the skin to hydrate the surface.

Scientific Basis for Humectants

A study published in the Journal of Investigative Dermatology highlights that humectants increase skin hydration by decreasing transepidermal water loss (TEWL). This process is crucial for maintaining skin barrier function and preventing conditions like eczema and dermatitis (1).

Another study from the International Journal of Cosmetic Science confirms that humectants improve skin elasticity and reduce roughness by maintaining optimal hydration in the stratum corneum, the outermost layer of the skin (2). These findings underline the role of humectants in skincare, making them essential ingredients for maintaining youthful, healthy-looking skin.

Common Types of Humectants

There are several types of humectants, each with unique properties that make them suitable for specific applications.

1. Glycerin (Glycerol)

Glycerin is quite possibly of the most usually involved humectant in skincare. It is a characteristic compound got from plant oils or creature fats. Due to its ability to attract moisture from both the air and deeper skin layers, glycerin helps to keep skin soft and hydrated.

A 2016 study in Clinical, Cosmetic and Investigational Dermatology confirmed that glycerin is effective in improving skin hydration and barrier function, especially in individuals with dry or compromised skin (3). It also enhances the penetration of other skincare ingredients, making it a popular choice in moisturizers and serums.

2. Hyaluronic Acid

Hyaluronic corrosive is a normally happening polysaccharide tracked down in the skin, connective tissues, and eyes. It can hold up to 1,000 times its weight in water, making it a super humectant in skincare. Hyaluronic acid works by binding to water molecules and locking moisture in the skin.

Research from the Journal of Clinical and Aesthetic Dermatology shows that hyaluronic acid reduces wrinkles, improves skin elasticity, and accelerates wound healing (4). It is commonly used in anti-aging products to plump the skin and minimize fine lines.

3. Urea

Urea is a characteristic compound found in the skin's Normal Saturating Element (NMF). It is an excellent humectant that helps to soften rough, dry skin and improve its ability to retain moisture. Urea additionally has gentle peeling properties, making it advantageous for conditions like psoriasis and skin inflammation.

A study published in the British Journal of Dermatology demonstrated that urea-based creams significantly improved skin hydration and reduced symptoms in individuals with dry skin conditions (5). Its dual action of moisturizing and exfoliating makes it highly effective in skincare formulations.

4. Propylene Glycol

Propylene glycol is a synthetic humectant commonly used in cosmetics and personal care products. It helps to draw water into the skin and prevent it from drying out. Propylene glycol is also used in pharmaceuticals to enhance the absorption of active ingredients.

A study in Toxicology Reports found that propylene glycol is safe for use in skincare at low concentrations (6). However, it may cause irritation in sensitive individuals, so it is important to monitor the skin for any adverse reactions.

5. Sorbitol

Sorbitol is a sugar alcohol derived from fruits like apples and berries. It functions as a humectant by attracting water to the skin and hair. Sorbitol is also used as a sweetener in food and pharmaceutical products. In skincare, it helps to retain moisture and improve product texture.

According to research in the Journal of Cosmetic Dermatology, sorbitol provides effective hydration without leaving a greasy residue, making it ideal for lightweight moisturizers (7).

Benefits of Humectants

1. Hydration

The primary benefit of humectants is their ability to attract and retain moisture in the skin and hair. This hydration helps to maintain the skin's barrier function, reducing the risk of irritation and inflammation. Well-hydrated skin also appears plumper, smoother, and more youthful.

2. Improved Skin Elasticity

Humectants, particularly hyaluronic acid and glycerin, help to improve skin elasticity. By keeping the skin hydrated, they prevent sagging and reduce the appearance of fine lines and wrinkles.

3. Enhanced Absorption of Active Ingredients

Humectants increase the permeability of the skin, allowing other active ingredients to penetrate more deeply. This makes products like serums and treatments more effective.

4. Exfoliation

Some humectants, such as urea, also have keratolytic properties, meaning they help to remove dead skin cells. This gentle exfoliation improves skin texture and promotes cell turnover.

Drawbacks of Humectants

While humectants offer numerous benefits, they also have certain drawbacks, particularly in dry environments.

1. Dehydration in Dry Climates

In environments with low humidity, humectants may draw moisture from the deeper layers of the skin rather than the air, leading to dehydration. To counteract this, humectants are often combined with occlusive agents like oils or butters to lock in moisture.

2. Potential for Irritation

Some humectants, especially synthetic ones like propylene glycol, can cause irritation in sensitive individuals. Patch testing new products is important to ensure they are suitable for your skin type.

Conclusion

Humectants play a crucial role in skincare by attracting and retaining moisture, which is essential for maintaining healthy, hydrated skin. From natural compounds like glycerin and hyaluronic acid to synthetic options like propylene glycol, humectants are versatile ingredients with scientifically proven benefits.

While they are highly effective in improving skin hydration, elasticity, and texture, it’s important to use them appropriately, particularly in dry climates. Pairing humectants with occlusives ensures that moisture is locked in, maximizing their benefits and preventing dehydration.

References

1. Rawlings, A. V., & Harding, C. R. (2004). Moisturization and skin barrier function. Journal of Investigative Dermatology, 124(5), 715-720.
2. Lodén, M. (2003). Role of topical emollients and moisturizers in the treatment of dry skin barrier disorders. American Journal of Clinical Dermatology, 4(11), 771-788.
3. Z. Draelos, A. B. (2016). The role of glycerin in moisturizing and hydrating the skin. Clinical, Cosmetic and Investigational Dermatology, 9, 257–264.
4. Baumann, L. (2007). Skin aging and hyaluronic acid. Journal of Clinical and Aesthetic Dermatology, 5(3), 55–60.
5. Suminoe, A., et al. (2013). Efficacy of urea-containing lotion for dry skin. British Journal of Dermatology, 169(4), 741-746.
6. Rowe, R. C., et al. (2016). Safety of propylene glycol in skincare products. Toxicology Reports, 3, 943-952.
7. Panayiotis, K., et al. (2005). Sorbitol in skin hydration. Journal of Cosmetic Dermatology, 4(3), 180-185.