Collagen supplements reduce joint pain and improve mobility

What this study actually shows: In young, physically active adults, taking 5g of collagen peptides daily for 12 weeks reduced activity-related knee pain slightly more than placebo (19mm vs 14mm improvement on a pain scale)

Pain relief is limited: This study only found reduced knee pain during physical activity — not at rest — placebo group improved by 74% as much as the collagen group — the actual benefit of collagen over placebo is very small (~5mm on a pain scale)

Industry funding concern: The study was paid for by the company that makes the collagen product being tested, and one researcher works at a private collagen research institute — this is a conflict of interest

Statistics are incomplete: Multiple outcomes were tested without proper statistical correction, meaning some "significant" results may be due to chance

Bottom line: This study provides weak and limited evidence — results only apply to activity-related pain in young, healthy adults, and key parts of the claim (mobility, general pain relief) are not supported.