Collagen
The most abundant protein in the body, a major component of skin, tendons, bones, cartilage and blood vessels, whose production declines with age.
Collagen makes up ~30% of the body’s protein. It is the structural « glue » that gives tissues strength and elasticity: skin, tendons, ligaments, bone, cartilage and the walls of blood vessels. There are several types (I, II, III and so on) depending on the tissue.
The original angle (the myth and the reality of supplements): the craze for collagen supplements deserves some nuance.
The classic counter-argument: « eating collagen doesn’t make collagen », because it is digested into amino acids like any protein and does not go « straight » to the skin. That is partly true, but…
Recent research adds nuance: hydrolysed collagen (peptides) releases specific di- and tripeptides (such as prolyl-hydroxyproline) that may act as signals, stimulating cells (fibroblasts) to make more collagen. Several studies show modest but real benefits for skin elasticity and hydration, and for joint pain. The debate remains open but leans towards a partial effect.
The indispensable cofactors: making collagen requires vitamin C (a key enzymatic cofactor; its deficiency causes scurvy, the disease of collapsing collagen), zinc, copper and amino acids (glycine, proline). A collagen supplement without these cofactors (especially vitamin C) is less effective.
Decline with age: collagen production drops from around age 25 to 30 (~1% a year), accelerated by sun (UV), smoking, sugar (glycation) and oxidative stress. Hence wrinkles, sagging and joint fragility.
A global approach: rather than betting everything on supplements, supporting collagen means getting enough protein, vitamin C, sun protection, stopping smoking, limiting sugar (glycation « caramelises » and stiffens collagen), and sleeping well.
Food sources: bone broths, animal skin and cartilage, fish (with the skin). The body also makes its own collagen from any protein plus cofactors.