„Collagen powder can't work because the stomach digests it — a waste of money.”

The di- and tripeptides of hydrolysed collagen (prolyl-hydroxyproline) demonstrably appear in blood and skin and act as signals that stimulate fibroblasts. Meta-analysis (19 RCTs, n=1,125): 2.5–10 g/day over 8–12 weeks measurably improves skin hydration and elasticity; a small effect on knee pain. What's true in the myth: the effect is modest, and most trials were manufacturer-funded.

Last reviewed: 6 September 2026

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