Types I, II and III collagen do different jobs, and marine and bovine sources are not interchangeable. Here is what the clinical evidence shows on dosage, bioavailability and timeline — and how to pick a supplement that matches your actual goal.

Collagen is the most abundant protein in the body — but natural production declines with age. A 2026 review of nearly 8,000 participants found cautiously positive evidence for skin hydration, joint comfort, and muscle health from hydrolyzed collagen peptides. Here's what the research actually shows.