A half-life is the time it takes for half of something to be replaced, broken down or cleared. Cartilage collagen's half-life has been estimated at 117 years.
Also called biological half-life.
The term is used in two ways on this site.
For tissue, it means how long the body takes to replace half of a protein. Verzijl and colleagues estimated it for collagen from the slow conversion of aspartic acid to its mirror-image form, which builds up the longer a protein stays in place. They put the half-life of cartilage collagen at 117 years and skin collagen at 15 (Verzijl 2000). Radiocarbon dating later found virtually no replacement of cartilage collagen after skeletal maturity (Heinemeier 2016). A third method, based on a different chemical change in ageing proteins, found faster turnover in ankle cartilage than in the hip (Hsueh 2019). The long life lets sugar-derived compounds called AGEs build up in cartilage collagen (Verzijl 2000).
For compounds taken into the body, half-life means how long it takes for half to be cleared from the blood. In rats given curcumin with piperine, curcumin's elimination half-life fell while its overall absorption rose (Shoba 1998).
Its collagen barely does, on most measurements. Radiocarbon dating of knee cartilage from 23 people found virtually no replacement of the collagen network after the...
Type II collagen is the main collagen in joint cartilage. Collagen makes up about two-thirds of adult cartilage's dry mass, and type II is its principal molecule, woven...