Collagen: Usage in Health and Cosmetics

Collagen is the most abundant fibrous structural protein in the body, accounting for approximately 30–35% of the total protein content. With its triple-helix structure formed by three polypeptide chains, it provides tissues with high tensile strength. To date, over 28 types of collagen have been identified, with Type I, II, and III being the most common. Type I is found in rigid tissues such as bone, skin, and tendons; Type II in cartilage; and Type III in more elastic tissues. Collagen synthesis begins intracellularly; fibroblasts and other cells produce procollagen. Mature collagen fibrils are formed through enzymatic processes and assemble via cross-linking to form durable structures within the tissue matrix. Deficiencies or malfunctions in collagen can lead to connective tissue disorders, osteoporosis, and skin aging.

Collagen is the most abundant fibrous structural protein in the human body, comprising about 30–35% of total body protein. As the main component of connective tissue, collagen provides mechanical strength, flexibility, and shape to tissues. Its molecular structure is characterized by a right-handed triple helix formed by three polypeptide chains, conferring high tensile strength. More than 28 types of collagen have been identified, with Type I, II, III, V, and XI being the most common. Type I predominates in bones, skin, and tendons; Type II in cartilage; and Type III in elastic tissues. Collagen synthesis begins in fibroblasts, osteoblasts, and chondrocytes, where procollagen precursors undergo enzymatic modifications to form mature collagen fibrils. These fibrils organize through cross-linking into durable structures in the extracellular matrix. Disruptions in collagen synthesis are associated with connective tissue disorders, osteoporosis, and dermatological aging (Shoulders & Raines, 2009; Ricard-Blum, 2011; Myllyharju & Kivirikko, 2004).

Over 28 types of collagen have been identified in the human body, with only a few playing essential roles in the structural integrity and function of connective tissues.

●       Type I: The most abundant form, found in skin, bone, tendons, ligaments, teeth, and the cornea. Provides high tensile strength.

●       Type II: Mainly located in cartilage, contributing to its elasticity and structural support. Also present in the vitreous body of the eye.

●       Type III: Common in flexible connective tissues such as skin, vascular walls, and organ-support structures. Often coexists with Type I and contributes to tissue elasticity.

Collagen has a triple-helical structure formed by tightly wound chains rich in glycine, proline, and hydroxyproline, which are essential for its mechanical stability.

 Synthesis begins in fibroblasts, osteoblasts, and chondrocytes with the production of procollagen. This precursor undergoes post-translational modifications, notably hydroxylation of proline and lysine, which requires vitamin C. Once secreted into the extracellular matrix, procollagen is converted into mature collagen and assembles into fibrils. Cross-linking, particularly through the action of lysyl oxidase, strengthens the fibrils. Defects in this process can lead to connective tissue disorders (Shoulders & Raines, 2009; Myllyharju & Kivirikko, 2004).

Collagen provides mechanical strength and elasticity to various tissues. It maintains structural integrity in the skin, bones, tendons, ligaments, cartilage, and blood vessel walls. In the skin, it preserves elasticity and aids wound healing; reduced production with aging leads to wrinkles and sagging. In bones, collagen forms the organic matrix that is essential for both flexibility and strength. In tendons and ligaments, it transmits muscular forces to bones. Type II collagen supports the elasticity of cartilage, while Type III enhances elasticity in blood vessels and organs. Collagen is also crucial for tissue repair and cellular regeneration.

Collagen is essential for the elasticity and resilience of the skin. Aging reduces collagen production, leading to wrinkles and sagging. Depletion of collagen fibers compromises structural integrity and slows regenerative processes. UV radiation accelerates collagen breakdown by activating destructive enzymes. Lifestyle factors such as smoking, poor nutrition, and environmental exposure further exacerbate this process. Healthy habits and the use of retinoids or peptides can stimulate collagen production. Modern medical aesthetic interventions aim to boost collagen synthesis and improve skin health.

More than 28 collagen types have been identified in humans; however, Types I, II, and III are structurally and functionally prioritized. Type I collagen is abundantly found in tissues requiring mechanical strength, such as skin, bone, tendons, and ligaments, and provides high tensile strength. Type II collagen is primarily found in cartilage tissue, undertaking tissue flexibility and support functions. Type III collagen is found in blood vessel walls and flexible connective tissues, supporting tissue elasticity. Other collagen types play a role in structural organization according to tissue specificity. Disruptions in collagen synthesis and regulation can lead to serious impairments in tissue function.

Collagen biosynthesis begins with the intracellular synthesis of procollagen polypeptides, which undergo hydroxylation of proline and lysine residues in the endoplasmic reticulum—a process that requires vitamin C. The procollagen molecules are secreted into the extracellular matrix and processed by proteases into mature fibrils. These fibrils are stabilized by cross-linking via lysyl oxidase.

 Collagen metabolism is tightly regulated by matrix metalloproteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs). Dysregulation can lead to pathological tissue degradation and loss of homeostasis.

As the most abundant structural protein, collagen imparts mechanical strength and flexibility to tissues. It forms the scaffold of connective tissue and plays critical roles in bones, tendons, cartilage, and vasculature. Beyond structural support, it regulates cell behavior, aiding tissue regeneration and repair. Type I dominates in bone, tendon, and skin; Type II is vital in cartilage; other types have organ- and vessel-specific functions.

With age, collagen synthesis declines, resulting in tissue laxity, wrinkles, and structural weakening. MMP activity increases, while natural inhibitors decrease, disrupting tissue integrity. Similar degenerative changes occur in non-cutaneous tissues—bone fragility increases, cartilage deteriorates, and tendon resilience diminishes. These alterations underlie many age-related clinical conditions.

Defects in collagen synthesis or structure can lead to various clinical conditions.

●       Scurvy, caused by a vitamin C deficiency, impairs hydroxylation in collagen synthesis, leading to bleeding gums, poor wound healing, and tissue fragility.

●       Osteoporosis involves decreased collagen in bone matrix, increasing fracture risk.

Collagen supplements, both oral and topical, have become widespread. Oral collagen peptides are absorbed into the bloodstream and have been shown to enhance collagen synthesis in the skin, joints, and bones. Clinical studies report improved skin elasticity, reduced joint pain, and increased bone density with regular supplementation. Topical products aid hydration, wound healing, and anti-aging effects. However, standardized dosing and efficacy remain subjects of ongoing research, and further robust clinical trials are necessary.

Collagen is a key ingredient in anti-aging cosmetic products. Its decline accelerates visible signs of aging, thus collagen-based serums, creams, and masks aim to restore elasticity and firmness. It also features in products supporting hair and nail health. Collagen's role in wound healing has applications in dermatology. Additionally, its antioxidant properties help counteract UV-induced free radical damage, preserving skin integrity.

Advances in biotechnology have enabled applications of collagen in regenerative medicine and nanotechnology. Recombinant collagen production supports tissue engineering and organ repair. Nanocarrier systems improve delivery and efficacy of collagen-based drugs and cosmetics. Personalized medicine approaches are being developed to tailor collagen therapies based on individual genetic and metabolic profiles. These innovations hold transformative potential in treating collagen-related diseases and combating aging.

Collagen supplementation is generally considered safe, although dosage, formulation, and individual sensitivity are crucial factors to consider. Common oral doses range from 2.5 to 10 grams per day. Side effects are rare but may include allergic reactions or gastrointestinal discomfort. Use during pregnancy, breastfeeding, or in chronic illness should be supervised by healthcare professionals. With proper quality control and guidance, collagen supplements can play a supportive role in maintaining the health of healthy individuals.

Collagen is a structural protein of critical importance in both health and cosmetic applications. It ensures tissue strength, elasticity, and integrity, but declines with age, contributing to functional loss and disease. Supplements and cosmetic interventions aim to mitigate these effects. Future biotechnological innovations and personalized therapies promise to enhance collagen-based health solutions. Thus, collagen research must continue from a multidisciplinary perspective and be integrated swiftly into clinical practice.