Does collagen need vitamin C to work?

Two collagens: the one you eat, which needs no vitamin C to be absorbed, and the one your cells make, which cannot fold without it

Does collagen need vitamin C to work is a question that runs two different collagens together under one word, and the honest page separates them first, because the answer is no for one and yes for the other and the shelf's sentence, that collagen needs vitamin C to work, is true of the collagen it is not selling and false of the one it is. The first collagen is the one a reader eats: the hydrolysed collagen in a capsule or a scoop, cattle hide or fish skin cooked to gelatin and cut by enzymes into short peptides. What it means for an eaten protein to work, in the only sense a protein can work on its own, is to be digested and absorbed, and that process has no vitamin C in it at any step. In the stomach, acid unfolds the peptides and pepsin begins cutting them; in the small intestine, the pancreatic proteases and the peptidases on the gut wall cut them further, to free amino acids and to di- and tripeptides, pairs and triples of amino acids that the gut wall absorbs through its own transporters; and over the following hour or two the amino acids and small peptides appear in the blood, with glycine, proline and hydroxyproline raised above their fasting levels and a few specific dipeptides measurable for several hours. A reader who takes a collagen capsule with a vitamin C tablet and a reader who takes it alone absorb exactly the same amino acids in exactly the same amounts over exactly the same hours, because vitamin C plays no part in protein digestion, and the three numbers that organise the vitamin C question, 12mg for the label, 50mg for the protocol and 80mg for the reference intake, are on the vitamin C with collagen page. The second collagen is the one a reader's cells make, and this is the collagen the sentence is true of. Every collagen fibre in a reader's skin, tendons, ligaments, bones and vessels was assembled by a fibroblast or its relative from amino acids in the body's pool, drawn from whatever protein was eaten, a collagen supplement, a chicken breast or a lentil, and from the body's own synthesis of glycine and proline, and the assembly has a step that depends on vitamin C absolutely. The fibroblast makes a long chain of amino acids in the collagen sequence, and before three such chains can wind together into the stable triple helix that collagen is, enzymes have to add hydroxyl groups to many of the proline and lysine residues along the chain, the prolyl hydroxylases and lysyl hydroxylases, and those enzymes require vitamin C as a cofactor, using it to keep their iron in the state the reaction needs; without vitamin C the chains are made but cannot be hydroxylated, cannot fold into a stable helix, and fall apart inside the cell or soon after secretion, so that no new stable collagen is laid down anywhere in the body. That is scurvy, and its signs, bleeding gums, bruising, wounds that will not heal and old scars that reopen, are the signs of a body unable to make collagen because the bricklayer has downed tools for want of one cofactor, while the bricks, the amino acids, lie in abundance.

Bricks and the bricklayer: why the bricklayer is already on site, why vitamin C is on the label anyway, what the protocol's 50mg was for, and the worked example

So collagen needs vitamin C to work the way bricks need a bricklayer, and the honest page follows the metaphor to its two conclusions. The bricks are the amino acids, and they arrive from any protein; a reader's fibroblasts do not know or care whether the glycine they are using came from a collagen capsule or from an egg, since digestion strips every protein to the same pool, so that the collagen supplement is a delivery of bricks to a yard that any mixed diet keeps stocked, which is a separate question from this page's and is answered on the pages about what collagen does for each tissue. The bricklayer is the fibroblast with its vitamin C-dependent enzymes, and the question the sentence actually raises is whether the bricklayer is on site, which is to say whether the reader has enough vitamin C for the hydroxylases to run, and for almost every reader the answer is yes before any supplement is considered. The hydroxylases, like every enzyme that uses a cofactor, saturate: plasma and tissue vitamin C rise steeply with intake up to around 100 to 200mg a day, at which point the tissues are full, the kidney excretes the excess and the enzymes have every molecule they can use, and more vitamin C makes them hydroxylate no faster, which is the dose-response curve with its plateau on the vitamin for ligament healing page. A satsuma supplies around the 80mg reference intake, a pepper or a serving of broccoli supplies more, and a reader eating any fruit or vegetables regularly is on the plateau, with a bricklayer on site who will not work faster for being handed more cofactor. The reader for whom the sentence is true in practice is the one eating no fruit or vegetables at all, for months, who is on the climb of the curve or at the bottom of it, and for that reader the honest advice is fruit rather than a collagen capsule's 12mg, since 12mg is a seventh of a satsuma and will not lift them far. Why, then, is vitamin C on a collagen label at all, and the honest page gives the two reasons, neither of which is that a reader is short. The first is the register: vitamin C holds the authorised sentence that it contributes to normal collagen formation for the normal function of skin, cartilage, bones, gums, teeth and blood vessels, and a product may print that sentence if it supplies at least 15% of the reference intake per daily dose, which is 12mg, so that a collagen capsule with 12mg of vitamin C may lawfully say something about collagen formation that a collagen capsule without it may not, which is why almost every collagen product on the shelf contains exactly that much. The second is the protocol: the pre-loading tendon trial gave 15g of gelatin with around 50mg of vitamin C about an hour before loading, including the vitamin C as the cofactor the hydroxylases would need if the gelatin's amino acids were built into tendon collagen, a sensible design choice for a trial of a mechanism, and not a finding that gelatin without vitamin C failed, since no arm tested that, and the three senses in which the two are taken together are on the collagen and vitamin C together page. The worked example pairs the two at the label threshold, stated on its true terms: two capsules, 1200mg hydrolysed type 1 marine collagen with 12mg vitamin C at 15% of its reference value plus zinc, 120 for £16.99 at 28p a day, lab tested and UK made, the 12mg being the amount that permits vitamin C's collagen formation sentence and a fraction of what a piece of fruit supplies, the collagen absorbed identically with or without it and holding no claim of its own. Does collagen need vitamin C to work: the eaten collagen does not, the made collagen does, the bricklayer is already on site in anyone eating fruit, and the vitamin C on the label is for the sentence and not the shortage.

What to check on the label