Collagen Peptides Ingested
Hydrolyzed collagen powder or capsules enter the digestive tract.
- 10 g: Typical daily dose (common studied dose)
- Bovine / marine: Source (hydrolyzed type I collagen)
- 2–5 kDa: Peptide size (pre-hydrolyzed molecular weight)
- Gly-Pro-Hyp: Signature motif (collagen's repeating triplet)
What is hydrolyzed collagen
Enzymatically pre-broken collagen from animal connective tissue.
Why hydrolysis matters
Smaller peptides absorb far better than intact collagen.
Intact collagen protein is too large to be absorbed intact.
Common supplement forms
Sold as flavorless powder, [], or drinkable shots.
Peptide Digestion
Pepsin and proteases cleave peptides into absorbable fragments.
- Pepsin, trypsin: Key enzymes (stomach and pancreatic proteases)
- 2–3 residues: Fragment size (di- and tripeptides)
- ~1–2 hrs: Digestion window (stomach to small intestine)
- Pro-Hyp: Resistant dipeptide (survives digestion intact)
Stomach breakdown
Pepsin starts cutting long collagen peptide chains.
Intestinal digestion
Pancreatic and brush-border enzymes finish the cleavage.
Why Pro-Hyp survives
This dipeptide resists further breakdown by enzymes.
Pro-Hyp and Hyp-Gly dipeptides appear intact in human blood.
Bloodstream Delivery
Absorbed peptides travel through blood to skin and joints.
- ~1–2 hrs: Peak plasma level (after oral ingestion)
- ~30×: Pro-Hyp rise (above baseline blood levels)
- ~4–12 hrs: Plasma half-life (peptide clearance from blood)
- Skin, cartilage: Accumulation site (collagen-rich target tissue)
Intestinal absorption
Small peptides cross the gut wall directly.
Plasma transport
Peptides circulate freely through the bloodstream.
Tissue targeting
Peptides accumulate preferentially in skin and cartilage.
Radiolabeled studies show peptides concentrating in skin tissue.
Fibroblast & Chondrocyte Stimulation
Peptides signal skin and cartilage cells to build new collagen.
- Fibroblasts, chondrocytes: Target cells (skin and cartilage cell types)
- ERK / MAPK: Signaling pathway (proposed peptide signaling route)
- +~65%: Collagen synthesis (in vitro fibroblast studies)
- Elastin, HA: Also stimulates (other matrix proteins)
Fibroblast activation
Peptide fragments act like signaling molecules on fibroblasts.
Chondrocyte activation
Similar peptides stimulate cartilage-building chondrocyte cells.
Matrix remodeling
Cells increase collagen, elastin, and hyaluronic acid output.
Cell-culture studies show measurable collagen gene expression increases.
Evidence Assessment — Skin & Joint Outcomes
Human trials show modest, not dramatic, benefits.
- ~19 RCTs: Skin elasticity trials (meta-analyzed skin studies)
- ~8–16%: Skin hydration gain (over 8–12 weeks typical)
- ~15–30%: Joint pain reduction (in osteoarthritis trials)
- Moderate: Evidence grade (small trials, industry funding common)
Skin elasticity evidence
Systematic reviews report modest elasticity and hydration gains.
Joint pain evidence
Some trials show reduced pain in osteoarthritis patients.
Evidence limitations
Many studies are small, short, or industry-funded.
Effect sizes are real but modest — not a cure.