Collagen Peptides — The Structural Protein Supplement
Collagen is the most abundant protein in the human body, comprising ~30% of total protein mass. It forms the structural scaffold of skin, tendons, ligaments, cartilage, and bone. Collagen synthesis declines ~1% per year after age 25, driving skin aging, joint degradation, and bone loss. Hydrolysed collagen peptides (HCP) are the most bioavailable supplemental form.
Mechanism of Action
Orally ingested collagen peptides are absorbed as dipeptides (Pro-Hyp, Hyp-Gly) that accumulate in skin and cartilage tissue. They stimulate fibroblasts to synthesise new collagen and hyaluronic acid via TGF-β signalling. They also provide the amino acid substrate (glycine, proline, hydroxyproline) for collagen synthesis.
Human Trial Evidence
A 2019 Journal of Drugs in Dermatology meta-analysis of 11 RCTs (805 patients) found collagen peptides significantly improved skin elasticity, hydration, and wrinkle depth. A 2017 Applied Physiology, Nutrition, and Metabolism RCT showed 15 g/day collagen peptides + vitamin C reduced knee pain and improved function in athletes over 24 weeks.
Dosing Protocol
5–15 g/day of hydrolysed collagen peptides. Skin benefits: 2.5–10 g/day. Joint benefits: 10–15 g/day. Best taken with vitamin C (essential cofactor for collagen synthesis). Marine collagen has smaller peptides and may have better bioavailability than bovine. Type I collagen for skin; Type II for joints.
Safety & Contraindications
Excellent safety profile. Derived from bovine, marine, or porcine sources — not suitable for vegans or those with fish/meat allergies. Mild GI effects at high doses. Contains hydroxyproline which may elevate urinary oxalate — caution in kidney stone history. No significant drug interactions.
Key Papers
Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo-controlled study
Skin Pharmacology and Physiology · 2014
Collagen supplementation as a complementary therapy for the prevention and treatment of osteoporosis and osteoarthritis
Reumatologia · 2018