Collagen in connective tissue: tendons, ligaments and fascia

Evidence status M3: Collagens are proteins that assemble into fibres and in that form take up tensile forces. They sit outside the cells in the extracellular matrix, where together with water and further molecules they form the load-bearing scaffold of a tissue. Shoulders and Raines (2009), Annual Review of Biochemistry describe how the triple helix is built and what its stability depends on. Limit: this is structural biology on the body's own tissue and not work on the intake of a food supplement. How the terms on packs are meant is placed by collagen as a structural protein and labels in the guide.

Evidence status M3: The collagen family comprises several types that differ in their molecular build and in their distribution in the body. Ricard-Blum (2011), Cold Spring Harbor Perspectives in Biology gives an overview of this family and of the tissues in which the individual types appear. Limit: the work describes the biology of these proteins and establishes no link to a product. A type stated on a pack therefore names a structural property of the raw material and not a benefit. Which further details a label carries, and where their legal limits lie, is set out by cofactors of collagen formation and their claim limits.

Evidence status M3: Tendons and skeletal muscle change their matrix when they are loaded mechanically. Build-up and remodelling run as the body's own processes over longer periods. Kjaer (2004), Physiological Reviews summarises this physiological adaptation. Limit: it is a physiological overview without any link to supplementation, without an amount and without an endpoint from an intervention study. Why research models on skin and collagen are to be read separately from this is shown by placing research models on skin and collagen separately.

Not legally assertable: Nothing follows from the build of a tissue about an ingested product changing mobility, load capacity, complaints, recovery or the avoidance of injuries. Structure and effect are two separate levels, and this article stays on the first. A separate existing article covers that other subject field: the joint and bone subject in the existing article.

Evidence status N: A robust statement about ingested collagen and the function of connective tissue in humans would need a defined population, a comparison group, a set duration and a pre-specified endpoint. No such primary source is documented in this article. The gap is therefore named and not covered over with review literature. Which attributes a label actually states is described by dosage forms as a label attribute.