What does collagen protein do?

The noun: what collagen protein does in the body

What does collagen protein do is a definition question that has to be answered twice, once for the noun, collagen the body's protein, and once for the verb, collagen the supplement, because the two share a name and a chemistry and do very different things, and most of the aisle's confusion comes from letting the first answer stand in for the second. The noun first. Collagen is the most abundant protein in the human body, around a quarter to a third of all the protein a person carries, and it is a structural protein, the rope and the scaffold rather than the machinery: three chains wound into a triple helix, each chain a repeating sequence in which every third amino acid is glycine, with proline and hydroxyproline filling much of the rest, the hydroxyproline being the amino acid found almost nowhere else and the reason collagen can be detected in a food by measuring it. There are many types and three do most of the work. Type 1 forms the thick, strong fibres of skin's dermis, tendon, ligament, bone and the capsule around joints, tendon being almost entirely type 1 by dry weight, and it is the collagen supplements are made from and most trials are about. Type 2 forms the matrix of cartilage, a looser network holding water and proteoglycans that lets a joint surface bear load, and it is the collagen the undenatured type II supplement targets by a different proposed mechanism. Type 3 forms finer fibres alongside type 1 in skin, blood vessels and organs and is the collagen laid down first in healing tissue before type 1 replaces it. The body makes collagen in fibroblasts and their tissue-specific relatives, chondrocytes in cartilage and osteoblasts in bone, assembling the chains from glycine, proline and lysine, hydroxylating the proline and lysine with enzymes that require vitamin C as a cofactor, which is why severe vitamin C deficiency historically produced connective tissue failure and why vitamin C holds the register's collagen formation sentence, and then secreting and cross-linking the fibres outside the cell. Turnover is slow: dermal collagen is replaced over months, tendon and bone collagen over years, and the rate of synthesis falls with age and sharply in women after menopause, which is what collagen protein does when it stops doing enough, skin thinning and losing elasticity, tendons stiffening and adapting more slowly, joints losing cartilage matrix. That is the noun: the body's scaffold, made by its own cells from common amino acids with a vitamin's help, on a clock of months to years.

The verb: what collagen protein does when you eat it, and what it is good for by tier

The verb second, collagen protein as the supplement. It is the same protein taken from an animal, bovine hide, porcine skin or fish skin and scales, cleaned and extracted to gelatin, the partly unwound form that sets a jelly, and then hydrolysed by enzymes into peptides of a few hundred to a few thousand daltons, the fine powder in the tub, which no longer sets and dissolves in a warm drink. Eaten, it does what any protein does first: stomach acid and pancreatic enzymes cut the peptides further into free amino acids, a third of them glycine, and into small di- and tripeptides, which the gut absorbs, and these join the body's amino acid pool and are used wherever protein is being made that day, muscle, gut lining, enzymes, skin, with no address on the parcel, the reason a collagen dose cannot be sent to the knees. It then does the one thing that distinguishes it from other proteins, as research: small peptides, prolyl-hydroxyproline and hydroxyprolyl-glycine among them, survive digestion and circulate in the blood for hours after a dose, and in cell and animal work they act on fibroblasts and chondrocytes, prompting them to make more matrix, the proposed mechanism by which hydrolysed collagen might do more than an equal weight of its free amino acids, a hypothesis with human marker data behind it, a collagen synthesis marker doubling an hour after fifteen grams with vitamin C before loading, and no human outcome claim. What collagen protein is good for follows from that, by tier. Research tier, at trial doses: skin elasticity and hydration up a few percent by instrument at 2.5 to 10 grams over eight to twelve weeks; activity-related joint discomfort modestly down by questionnaire at around ten grams over twelve to twenty-four weeks; a tendon synthesis marker doubled before loading at fifteen grams, with one small clinical trial in Achilles tendinopathy beside exercise; and one bone density trial at five grams for a year, all small, mostly manufacturer-funded and claim-free. Food tier: four calories a gram, satiating as protein is, safe with no upper level, more expensive than whey. And the tier it fails: muscle, since it lacks tryptophan, carries a third of whey's leucine and does not drive muscle protein synthesis, so it is the wrong protein for the job the word protein usually means. It holds no authorised claim; the label's collagen sentence belongs to vitamin C, which contributes to normal collagen formation for the normal function of skin, cartilage, bones, teeth, gums and blood vessels, the cofactor named in the noun's paragraph. The worked example is the verb on its true terms: two capsules, 1200mg hydrolysed type 1 marine collagen with 12mg vitamin C plus zinc, 120 for £16.99 at 28p a day, lab tested and UK made, below the research band, taken for vitamin C's sentence and the habit. What does collagen protein do: as a noun, it holds the body together and is made by the body's own cells; as a verb, it feeds that process as any protein does, is researched for connective tissue at trial doses, and builds no muscle.

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