What causes low collagen?

Intrinsic and extrinsic: the two words dermatologists use, and which one does the visible damage

What causes low collagen is a question that usually arrives from a mirror, since skin is the one collagen tissue a person can watch, and the honest page borrows the two words dermatologists have used for decades to sort the causes of skin ageing, because they sort the causes of low collagen everywhere. The first word is intrinsic, meaning the ageing that comes from inside by genetic programme and happens to protected skin as surely as to exposed. Fibroblasts, the cells that make dermal collagen, slow their synthesis from the mid-twenties by around one percent a year, so that a sixty-year-old's dermis is making collagen at perhaps two thirds of the rate of a twenty-five-year-old's; the fibroblasts themselves become fewer and flatter, the collagen they make is less well organised, and the balance between making and breaking tips slowly towards breaking. On top of the slow slope sits one cliff: oestrogen supports dermal collagen, and in the five years after menopause the dermis loses around a third of its collagen content as oestrogen falls, with the rate of loss slowing afterwards, which is why women notice a change in skin texture in their early fifties that men of the same age do not, and why hormone replacement in trials preserves dermal collagen. Intrinsic low collagen is the cause nobody avoids, and the only levers against it are the slow building ones, a retinoid for the skin and, at the margin, the oral collagen trials' few percent by instrument. The second word is extrinsic, meaning destruction from outside, and this is the cause that does most of the visible damage. Ultraviolet light penetrates the dermis and switches on the matrix metalloproteinases, the enzymes that break down existing collagen and elastin, while suppressing new synthesis, so that each unprotected exposure removes collagen that took years to lay down; smoking does the same through its own chemistry and through reduced blood flow, with the smoker's skin measurably thinner in collagen than the non-smoker's at the same age; pollution contributes through oxidative stress; and sugar, over years, attaches to collagen fibres by glycation and stiffens and yellows them, the slowest of the extrinsic causes. The scale of the extrinsic contribution is visible in any older person: the skin of the inner upper arm or the buttock, protected for a lifetime, is smooth, even and relatively thick at seventy, while the skin of the face, neck and backs of the hands, exposed for the same lifetime, is lined, mottled and thin, and the difference between the two in the same body is the extrinsic damage, which studies put at most of the visible ageing of exposed skin. Extrinsic low collagen is the cause almost everyone can reduce, and the levers are protection, sunscreen and shade, not smoking, and a sensible diet, which preserve more collagen over a decade than any product adds.

The third cause, the cofactor deficiency, what does not cause low collagen, and the honest habit

The third cause is the one the first two words leave out, and it is the only true low collagen state in the medical sense: the cofactor deficiency. Collagen chains are folded into their triple helix by enzymes, the prolyl and lysyl hydroxylases, that require vitamin C, and without vitamin C the chains cannot be hydroxylated, cannot fold and are degraded inside the cell, so that no functional collagen is made anywhere in the body; this is scurvy, with bleeding and swollen gums, easy bruising, tiny bleeds around hair follicles, wounds that will not heal, fatigue and joint pain, appearing after weeks to months of very low intake. It is rare in the UK, confined to very restricted diets, alcohol dependence, some eating disorders and some older people eating little fresh food, it is a doctor's diagnosis from the symptoms and a blood level, and it reverses with vitamin C and a changed diet as the enzymes start working again. A reader who eats any fruit or vegetables in an ordinary week is not short of vitamin C and does not have this cause; the register's sentence, vitamin C contributes to normal collagen formation for the normal function of skin, is the lawful description of what sufficiency does. The minerals that collagen's other enzymes use, copper for cross-linking, zinc for remodelling and iron alongside vitamin C in the hydroxylases, have deficiency states too, rare and specific, and are met from food. What does not cause low collagen deserves its own paragraph because the shelf implies it daily: not eating collagen does not cause low collagen. Eaten collagen is digested to amino acids and small peptides like any protein, the body makes every collagen fibre on site from its amino acid pool, and a fed body carrying 1.6 to 2.2g of protein per kilogram has glycine, proline and lysine in surplus, so a person who has never eaten gelatin, stock or a collagen capsule in their life makes collagen at the rate their fibroblasts and their age dictate, no less; the oral collagen trials change skin by a few percent by instrument at 2.5g and above, which is a small addition on the building side and not the correction of a deficit, and no collagen deficiency exists as a condition. Two further things do not cause low collagen in the sense the question means: in tendon and cartilage, the carbon dating studies show the collagen laid down in youth is essentially never replaced, so the adult stock there is fixed whatever happens at the plate, and a stiffer tendon at fifty is cross-linking and not loss; and ordinary ageing of the face is mostly fat and bone change beneath the skin rather than dermal collagen alone. Low collagen is therefore time, which nobody avoids, sun and smoke, which almost everyone can reduce, and in rare cases a missing cofactor, which a doctor finds; the order of the levers is protection first, a retinoid second, and the habit third. The worked example is that habit, 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 vitamin C carrying its collagen formation sentence for skin and the zinc its protein synthesis sentence, the collagen below the 2.5 to 15g research band and holding no claim. What causes low collagen: intrinsic ageing, extrinsic destruction and, rarely, a missing cofactor, and never the absence of collagen from the plate.

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