Collagen Supplements in Skin Aging and Treatment—A Narrative Review

Skin aging is a multifactorial process that is dependent on mechanisms linked to age and hormonal changes and on external factors, primarily chronic exposure to ultraviolet radiation. One of the key elements of this process is the quantitative and qualitative changes in collagen. In recent years, there has been particular interest in oral supplementation with hydrolyzed collagen (HC), which is promoted as one of the tools to support anti-aging treatments. The purpose of this narrative review is to synthesize the importance of collagen in skin structure and function, discuss changes occurring during aging, and analyze current data on oral collagen supplementation. The following sections discuss the structure and function of collagen, its importance for skin integrity, the main mechanisms of collagen aging, available sources and forms of supplementation, as well as the clinical efficacy, safety, and interpretive limitations of the current literature. Oral supplementation with hydrolyzed collagen at doses of 2.5–10 g/day for at least 8–12 weeks is associated with improved skin hydration and elasticity, as well as a reduction in wrinkle depth, although study results are inconsistent, and the effect may be weaker in studies of the highest methodological quality and those free from industry funding. In clinical trials, hydrolyzed collagen preparations are typically highly purified (>90–97%) with minimal additives, enabling the isolated effect of the peptides to be evaluated. Future research should focus on independent, long-term randomized controlled trials, direct comparisons of commercial versus purified collagen peptides, and the contribution of synergistic additives to bioavailability and clinical efficacy. Such studies are essential to refine dosing recommendations and strengthen evidence-based use in both cosmetic and clinical settings.