Hydration is the secret to preserving skin barrier function, slowing aging, and improving skin texture. Skin hydration has a direct effect on the physiological processes of the skin, including barrier protection, immune response, and metabolic activity. The selection of high-functioning moisturizing ingredients is therefore not just to improve the tactile sensation of the skin but also to preserve the overall health of the skin. The five below ingredients are best known as the best moisturizers.
Hyaluronic Acid: The “Molecular Sponge” for Multi-Dimensional Hydration
Hyaluronic Acid (HA) is a naturally occurring glycosaminoglycan found in high concentrations in the dermis and epidermis. Its molecular architecture contains numerous hydroxyl groups, with which it can hydrogen bond to water molecules, forming a stable network of hydration.
The moisturizing capacity of HA is proportionate to its molecular weight:
- High-molecular-weight HA (>1000 kDa) forms a permeable film on the skin surface, preventing transepidermal water loss (TEWL);
- Low-molecular-weight HA (<10 kDa) penetrates deeper into the epidermis, activating hyaluronic acid synthase in keratinocytes and activating endogenous HA biosynthesis.
HA also promotes cell proliferation and migration by CD44 receptor-mediated pathways, augmenting barrier repair.
Ceramides: The “Structural Pillars” of the Lipid Barrier
Ceramides are the predominant components of stratum corneum intercellular lipids, comprising approximately 50% of total lipid content. They coexist with cholesterol and free fatty acids in a lamellar liquid crystal form and function as “mortar” in the “brick-and-mortar” skin system. Lack of ceramide leads to disorganization of lipid bilayer structure, increases TEWL, and produces dryness and sensitivity.
Exogenous addition of ceramides, particularly Ceramide 1, 3, and 6-II, has the ability to regain the lipid barrier function to enhance the mechanical strength and chemical stability of the stratum corneum. Moreover, ceramides regulate filaggrin expression to enhance the biosynthesis of natural moisturizing factors (NMF) and further enhance the water-holding capacity of the skin.
Glycerin: The “Water Carrier” for Penetrative Hydration
Glycerin, a polyol of three carbons, possesses high hygroscopicity due to the presence of hydroxyl groups. Its mechanism of moisture is by two main ways:
- First, it absorbs water from the surroundings to form a hydration layer that directly increases the level of water in the stratum corneum;
- Second, it penetrates into the stratum corneum deep and regulates the expression of aquaporin-3 (AQP3) to facilitate the transport and distribution of water in the epidermis.
Research has shown that glycerin not only promotes skin hydration but also boosts stratum corneum flexibility and elasticity, reducing micro-damage from dryness.
Squalane: The “Barrier Repair Agent” with Biomimetic Lipids
Squalane, the hydrogenated form of squalene, has excellent chemical stability and biocompatibility. Its molecular structure is highly comparable to that of squalene in sebum and is easily able to incorporate into the skin’s lipid matrix and repair compromised barrier structures. Squalane functions by forming a hydrophobic barrier film to reduce TEWL, restructuring the lipid bilayer to increase barrier function, and preventing lipid peroxidation damage through its antioxidant properties. Also, its lightweight texture makes it non-comedogenic and ideal for every skin type.
Panthenol: The “Hydration Activator” of Cellular Metabolism
Panthenol, a Vitamin B5 precursor, is reduced to pantothenic acid in the skin, an essential part of coenzyme A (CoA). Panthenol’s moisturizing action is attained through a variety of mechanisms:
- Stimulating proliferation and differentiation of keratinocytes to enhance barrier repair;
- Enhancing filaggrin degradation to increase NMF;
- Stimulating lipid synthesis in the stratum corneum to enhance barrier function.
Additionally, panthenol exhibits anti-inflammatory and soothing properties, alleviating inflammation caused by barrier damage and further maintaining skin hydration.
Conclusion
In summary, these five ingredients work synergistically through distinct molecular mechanisms to maintain skin hydration and barrier function. When selecting moisturizing products, it is essential to consider your skin type and needs, opting for formulations that incorporate these ingredients to achieve optimal skincare results.