What destroys collagen the most?

The top of the table: ultraviolet light, the one destroyer that has been quantified

What destroys collagen the most is a question that asks for a ranking, and the honest page gives one rather than the shelf's list, because the destroyers differ in size by an order of magnitude and a reader who treats them as equal spends their effort in the wrong place. At the top of the table, alone, sits ultraviolet light, and it sits there for a reason the other destroyers lack: it is the only one whose share of the damage has been quantified. Ultraviolet A penetrates into the dermis and ultraviolet B into the upper skin, and both generate reactive oxygen species that switch on the matrix metalloproteinases, the enzymes whose job is to break down collagen and elastin, while suppressing the fibroblasts' synthesis of new collagen, so that each unprotected exposure removes dermal collagen that took years to lay down and adds nothing back; repeated over decades, the result is the thinned, fragmented, disorganised collagen of photoaged skin, with its deep wrinkles, roughness, mottled pigment and loss of elasticity. The quantification comes from the comparison every older body carries: the skin of the inner upper arm or the buttock, protected for a lifetime, remains relatively smooth, even and thick at seventy, while the skin of the face, neck, forearms and backs of the hands, exposed for the same lifetime, is lined, mottled and thin, and studies comparing exposed and protected sites in the same people, and twins and populations with different sun histories, attribute the large majority of visible facial ageing in exposed skin to ultraviolet exposure rather than to intrinsic ageing. Nothing else on the list has been measured against the whole and found to be most of it. The practical consequence is the least glamorous sentence in the collagen literature: a hat, shade and a daily broad-spectrum sunscreen on the face, neck and hands preserve more dermal collagen over a decade than any product, topical or oral, builds, and a reader who takes collagen while sunbathing unprotected has filled a bucket with a hole in it. The honest page places sunscreen first on every skin list it writes for this reason, and places it at the top of this table before turning to the destroyers that follow, each real and each smaller.

The rest of the table: smoking, corticosteroids, glycation, oestrogen loss, and unloading

Second is smoking, which earns its place by destroying collagen in every connective tissue the body has rather than in skin alone. Its chemistry generates oxidative stress and switches on the same matrix metalloproteinases as ultraviolet light, its nicotine constricts the small vessels that feed the dermis and reduces blood flow and oxygen delivery, and the result in skin is measurably thinner dermal collagen and more wrinkling in smokers than in non-smokers of the same age and sun history; in tendon, ligament and bone the same impaired blood flow slows every repair and is one of the best-documented modifiable brakes on healing. Stopping is the second-largest lever on the table and the only one that acts on all tissues at once. Third is corticosteroids, which most collagen lists omit and which the honest page ranks high because it is the best-documented pharmacological destroyer of collagen there is: topical steroid creams of moderate and high potency, used for long periods, and systemic steroids by mouth or injection, suppress fibroblast collagen synthesis and increase its breakdown, producing skin thinning, striae, easy bruising, visible vessels and slow wound healing, which is why potent steroid creams are prescribed in short courses with rest periods and why a steroid injection into or around a tendon weakens it. A reader on long-term steroids for a medical reason does not stop them for their collagen, but should know where their skin's thinning comes from and that no supplement replaces what the steroid suppresses. Fourth is glycation, the slowest destroyer: sugars in the blood attach to long-lived proteins over years, and collagen in skin and tendon, which turns over slowly, accumulates these advanced glycation end products, which cross-link the fibres abnormally, stiffen and yellow them and make them harder for the body to remodel, a process accelerated in diabetes and by a diet consistently high in sugar and the genuine reason a sensible long-term diet matters for connective tissue, though not a reason that anything happens at a mealtime. Fifth is the loss of oestrogen at menopause, a destroyer in the sense that it removes the support that was holding dermal collagen up: around a third of dermal collagen is lost in the five years after menopause as oestrogen falls, with the rate slowing afterwards, a loss that hormone replacement prevents in trials and that no supplement reverses. And for tendon, ligament and bone the table has one more entry that does not apply to skin: unloading. Those tissues build and maintain their collagen in response to mechanical strain, and rest, immobilisation or inactivity lowers their collagen synthesis below baseline within weeks, so that a cast, a sedentary year or a long illness destroys connective tissue collagen as surely as the sun destroys the skin's, and progressive load restores what inactivity allows to lapse. Nothing on the table is a nutrient deficiency except at the extreme, since vitamin C deficiency, scurvy, stops collagen being made at all and is rare, and nothing on the table is prevented by a supplement, since no capsule shades the skin, replaces a cigarette, reverses a steroid, removes sugar from the blood, restores oestrogen or loads a tendon. The worked example is the habit beside the hat, 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, below the 2.5 to 15g research band, carrying vitamin C's collagen formation sentence and protecting against none of the destroyers. What destroys collagen the most: the sun, by a measured margin, and the biggest lever on the table costs less than any tub.

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