Collagen Glossary

A complete reference covering collagen biology, types, sources, skin science, hair biology, joint health, and the key ingredients in beauty and wellness supplementation. Written to bridge the gap between scientific literature and practical supplementation decisions.

Collagen Biology

Collagen

The most abundant protein in the human body, constituting approximately 25-35% of total protein content. A family of fibrous structural proteins characterised by repeating Gly-X-Y triplet amino acid sequences that self-assemble into right-handed triple helices. Provides tensile strength and structural integrity to skin, bone, tendon, and ligament.

Procollagen

The intracellular precursor to collagen, synthesised in the rough endoplasmic reticulum of fibroblasts. Vitamin C is required for prolyl hydroxylation of procollagen - without it, the triple helix is unstable.

Tropocollagen

The basic structural unit of collagen fibres - a triple helix of three alpha chains measuring approximately 300nm long. Spontaneously assembles into collagen fibrils through self-organisation.

Extracellular Matrix (ECM)

The three-dimensional network of proteins and polysaccharides secreted by cells that provides structural and biochemical support to surrounding tissues. Major ECM components include collagens, elastin, hyaluronic acid, and proteoglycans.

Fibroblast

The primary cell type responsible for synthesising and maintaining the ECM in connective tissues. Fibroblast activity declines with age. Specific collagen peptides activate fibroblasts via receptor-mediated signalling to stimulate new collagen synthesis.

Matrix Metalloproteinases (MMPs)

A family of zinc-dependent endopeptidases that degrade ECM proteins including collagen and elastin. Pathologically upregulated by UV radiation, inflammation, and ageing - leading to net collagen degradation. MMP-1 is primarily responsible for Type I collagen degradation in photoaged skin.

Collagen Types

Type I Collagen

The most abundant collagen type in the human body, constituting approximately 90% of total collagen. The primary structural collagen of skin (70-80% of dermal dry weight), bone, tendon, ligament, and blood vessel walls.

Type II Collagen

The primary structural protein of hyaline cartilage, constituting approximately 90-95% of cartilage collagen. Two supplementation approaches: undenatured Type II (UC-II, 40mg) via oral immune tolerance; hydrolysed Type II (5-10g) as substrate for chondrocyte matrix synthesis.

Type III Collagen

A homotrimeric collagen found alongside Type I in skin, blood vessels, and internal organs. Particularly abundant in fetal skin and early wound healing. Type III provides pliability and elasticity alongside the tensile strength of Type I.

Undenatured Type II Collagen (UC-II)

Native (non-hydrolysed) Type II collagen in its intact triple helix conformation, derived from chicken sternum cartilage. Works via oral tolerance. Effective at 40mg daily. The most studied form for osteoarthritis management.

Collagen Sources and Processing

Marine Collagen

Collagen extracted from fish skin, scales, and bones - predominantly Type I. Smaller average peptide size after hydrolysis (2-3 kDa vs 3-5 kDa for bovine) provides superior bioavailability for skin applications. Preferred for skin-focused supplementation.

Bovine Collagen

Collagen derived from cattle, primarily from hides (providing Types I and III) and cartilage (providing Type II). The most widely used collagen supplement source. Hide-derived bovine collagen is appropriate for skin, tendon, and musculoskeletal applications.

Hydrolysed Collagen

Collagen that has been partially broken down by enzymatic or acid hydrolysis into smaller peptide fragments. Well-hydrolysed collagen (average less than 3 kDa) has high bioavailability; poorly hydrolysed material (greater than 10 kDa average) provides amino acid substrate rather than bioactive signalling peptides.

Collagen Peptides

Short amino acid chains derived from collagen hydrolysis, ranging from 0.3-20 kDa. The most bioavailable form of collagen supplement. Pro-Hyp and Gly-Pro dipeptides are the primary bioactive fractions, absorbed via PEPT1 transporters in the small intestine.

VERISOL

A specific bioactive collagen peptide (SBCP) from Gelita AG, standardised for skin applications. Multiple RCTs demonstrate VERISOL at 2.5g daily significantly improves skin elasticity and reduces periorbital wrinkles. The most extensively published SBCP for dermatological outcomes.

Pro-Hyp Dipeptide

Proline-hydroxyproline, a dipeptide unique to collagen that serves as a bioactive signalling molecule when absorbed from the gut. Detectable in human plasma within 60 minutes of oral collagen peptide ingestion, where it stimulates collagen synthesis and hyaluronic acid production in dermal fibroblasts.

Skin Biology and Ageing

Dermis

The second layer of skin beneath the epidermis. Approximately 70-80% of dermal dry weight is Type I collagen. The primary site of skin ageing changes at the structural level.

Photoageing

Skin ageing caused by chronic UV radiation exposure, distinct from intrinsic chronological ageing. UV-A penetrates to the dermis, generating reactive oxygen species that activate MMPs. Responsible for approximately 80% of visible facial ageing according to twin studies.

Intrinsic Ageing

Skin ageing driven by the passage of time independent of UV exposure. Features include reduced fibroblast collagen synthesis (declining approximately 1% per year after age 25), slower keratinocyte turnover, and decreased hyaluronic acid content.

Transepidermal Water Loss (TEWL)

The passive diffusion of water through the skin to the external environment. Elevated TEWL indicates compromised skin barrier function. Oral collagen peptides reduce TEWL in RCTs, suggesting improved barrier function.

Skin Elasticity

The ability of skin to return to its original shape after deformation, mediated primarily by elastin fibres and dermal collagen. Declines with age as elastin fibres fragment. Collagen peptide supplementation improves cutometer-measured elasticity in multiple RCTs.

Key Beauty and Wellness Ingredients

Hyaluronic Acid

A glycosaminoglycan polymer that is the primary hydration molecule of the dermal ECM. Can bind up to 6 litres of water per gram. 50% of total body HA is in the skin. Declines with age. Oral HA (120-240mg daily) reaches dermal fibroblasts to stimulate endogenous HA synthesis.

Vitamin C (Ascorbic Acid)

An essential vitamin and obligate cofactor for collagen biosynthesis. Required for prolyl hydroxylase and lysyl hydroxylase enzymes. Without adequate vitamin C, collagen cannot be assembled into functional fibres. Combining collagen peptides with vitamin C meaningfully improves the efficacy of the collagen synthesis protocol.

Astaxanthin

A ketocarotenoid produced by the microalgae Haematococcus pluvialis. The most potent natural antioxidant known, with singlet oxygen quenching activity 6,000 times greater than vitamin C. At 4-6mg daily, RCTs demonstrate reductions in UV-induced skin damage and improved elasticity.

Biotin (Vitamin B7)

A water-soluble B vitamin essential for fatty acid synthesis - critical for the membrane integrity of rapidly dividing keratinocytes. Clinical dose for nail and hair applications is 2.5mg (2,500mcg) daily - approximately 80x the RDA.

Silicon (Orthosilicic Acid)

The bioavailable form of silicon, absorbed from the proximal small intestine. Concentrated in connective tissues where it participates in collagen cross-linking. Choline-stabilised orthosilicic acid (ch-OSA) at 10mg daily improves skin roughness, hair tensile strength, and nail brittleness in RCTs.

Joints, Cartilage, and Connective Tissue

Articular Cartilage

The smooth hyaline cartilage covering the ends of bones at synovial joints. Composed primarily of Type II collagen (90-95% of cartilage collagen), aggrecan proteoglycan, and water. Limited self-repair capacity due to avascular nature.

Chondrocytes

The cells that maintain articular cartilage matrix. Chondrocyte anabolic activity can be stimulated by specific bioactive collagen peptides and mechanical loading.

Osteoarthritis

The most common joint disorder, characterised by cartilage degradation, subchondral bone remodelling, and pain. Type II collagen (UC-II at 40mg, or hydrolysed at 10g), glucosamine, and chondroitin have evidence for symptom management.

Collagen for Tendons

Tendons and ligaments are primarily Type I collagen structures. Pre-exercise collagen peptide supplementation (15-30 minutes before loading exercise, with vitamin C) has been shown to significantly increase collagen synthesis markers in tendon tissue.

Collagen Assessment and Testing

Cutometer

A device measuring skin biomechanical properties by applying suction to a defined skin area and measuring the resulting deformation and recovery. The standard measurement tool in collagen supplementation RCTs for objectively quantifying skin elasticity improvements.

Collagen Synthesis Markers

Blood biomarkers used to assess collagen turnover rates. Procollagen type I N-terminal propeptide (P1NP) reflects collagen synthesis; C-terminal telopeptide of type I collagen (CTX) reflects collagen degradation.

Bone Mineral Density (BMD)

A measure of the amount of mineral per area of bone, typically measured by DEXA scan. Collagen peptide supplementation (5g daily for 12 months) significantly improved BMD in post-menopausal women with osteopenia in the Konig et al. 2018 RCT.

Hair Biology and Keratin

Keratin

The primary structural protein of hair, nails, and the outer epidermis. An alpha-helical fibrous protein rich in cysteine - the disulfide bonds between cysteine residues provide keratin's characteristic strength and rigidity.

Anagen Phase

The active growth phase of the hair cycle, lasting 2-7 years for scalp hair. The length of anagen determines final hair length. Anagen duration is reduced by nutritional deficiencies (protein and iron) and hormonal changes.

Telogen Effluvium

Diffuse hair shedding caused by premature transition of large numbers of follicles to the resting phase, triggered by physiological shock 2-4 months before visible shedding. Triggers include rapid weight loss, post-partum hormonal changes, and nutritional deficiency.