INTRODUCTION
Skin aging is a multifactorial process influenced by various extrinsic and intrinsic factors, including ultraviolet (UV) exposure, environmental pollutants, genetics, and cellular senescence.1,2 These factors lead to alterations in the components of the extracellular matrix (ECM) within the dermis, resulting in skin dryness, diminished elasticity, and the formation of wrinkles.2,3 Hyaluronic acid (HA), a high molecular-weight anionic polysaccharide, is a key component responsible for water retention and structural support within the ECM.4,5 In humans, HA is most abundant in the skin, constituting 50% of the total body HA, highlighting its importance in skin physiology, followed by the vitreous of the eye and synovial fluid.6
HA enhances skin hydration and supports its structure through several mechanisms. It forms a hydrated gel-like matrix within the extracellular space, trapping water and maintaining hydration.7 Additionally, by forming a hydrated layer on the skin's surface, HA prevents water loss and protects against environmental aggressors such as pollutants and UV radiation.8 Moreover, HA provides structural support to the skin by interacting with other ECM components, such as collagen and elastin fibers. By binding to these fibers, HA helps stabilize the ECM, maintaining skin firmness and resilience. Interestingly, HA can also act as a signaling molecule through binding to specific cell surface receptors, influencing various cellular processes involved in skin repair, regeneration, and inflammation.9
Due to its diverse functions related to skin health, HA has emerged as a key molecule in anti-aging products.3 Research indicates that HA content in the skin declines with age and sun exposure, further emphasizing its correlation with skin aging.10 With advancements in production techniques, HA has found applications in topical skincare formulations and dermal fillers.11 More recently, there has been growing interest in oral HA supplementation for maintaining skin health and counteracting aging effects.12 Oral supplementation may offer unique advantages, including deeper distribution to dermal layers compared to topical application, and replenishment
