Current insights into collagen type I

Collagen is the most abundant protein in the human body — it makes up roughly a third of all the protein we contain. But collagen isn't a single molecule. There are 28 different types identified so far, each doing slightly different jobs in different tissues. Type I collagen is the dominant form, accounting for around 90 percent of the collagen in skin, bones, tendons, teeth, corneas, and the outer coverings of organs. Almost every clinical trial of oral collagen supplements uses type I collagen extracted from cow hide, pig skin, fish scales, chicken bone, or egg membrane.

This 2021 review from researchers at Universiti Putra Malaysia is a technical reference document — the kind of paper the pillar cites to establish what collagen actually is at the molecular level before discussing what it does. The authors comprehensively cover the triple-helix molecular structure, the biology of how the body makes collagen from scratch, all the current commercial extraction methods used to turn animal hides, bones, and scales into supplement powder, the physical and chemical properties that make type I collagen so useful in medicine, and the wide range of applications spanning wound healing, drug delivery, 3D-printed tissue scaffolds, cosmetics, and dietary supplements.

Unlike the clinical trial papers in this Data Center, this review does not report an intervention or an outcome. Its value is as the foundational biology reference that gives every other cited paper its context. When the pillar states that collagen makes up 90 percent of the protein in human skin, or when the "what is hydrolysed collagen" article explains that hydrolysis breaks the intact triple helix into smaller peptides, this is the paper that anchors those factual claims. Independent academic authorship and government-funded article processing charge make it the cleanest available reference for these foundational statements.