Does collagen really tighten loose skin?

The sceptic's checklist: the two boxes the collagen skin trials tick

Does collagen really tighten loose skin is a question in which the word really is the question, a sceptic's really, asked by someone who has seen the before-and-after photographs and wants to know whether anything stands behind them, and the honest page answers it by writing down the sceptic's own checklist, the three things that would convince a careful person that a supplement changed skin, and checking each against the trials, because the result is more precise than either the shelf's yes or the forum's no and a sceptic deserves the precision. The first box is a blinded, placebo-controlled trial, the design that rules out the thing a sceptic most suspects, expectation: participants randomly assigned to the supplement or to an identical-looking placebo, with neither the participants nor the people measuring them knowing who got which, so that any difference at the end cannot be the belief that one took the real thing. The oral collagen skin trials tick this box. The best-known of them randomised women to hydrolysed collagen peptides or to a placebo of identical appearance and taste for eight to twelve weeks, double-blind, and several independent groups have run the same design since, so the collagen skin result is not a testimonial or an open-label before-and-after but a proper trial finding, which is more than can be said for most of the skin supplement aisle. The second box is an objective instrument rather than a self-rating, because a sceptic knows that people on any supplement rate their skin as better and that a questionnaire measures hope as much as skin. The trials tick this box too. They measured elasticity with a cutometer, a probe that applies gentle suction to a small area of cheek and records how far the skin is drawn in and how fast and completely it springs back, hydration with a corneometer, which reads the skin surface's electrical capacitance, and in some trials fine wrinkle depth with a profilometer that maps the skin surface around the eye; none of these instruments knows what the participant took or hopes. Against placebo, the collagen groups improved on elasticity and hydration by a few percent at 2.5g a day and above over eight to twelve weeks, with 2.5g and 10g producing changes of similar size and the fine wrinkle result found in some trials, a small effect, replicated, and measured by machines. Two boxes of three are ticked, and a sceptic who stops reading here has learned that collagen really does something to skin instruments, which is a fair thing to have learned and the true half of the shelf's claim.

The third box, which is empty, what the instruments did not measure, and the levers that do reach loose skin

The third box is the one the question is actually about, and it is empty: a trial in loose skin specifically. Loose skin, the thing a reader who has lost thirty kilograms sees on their arms, abdomen and thighs, or a reader of sixty sees on their neck and upper arms, is not ordinary ageing facial skin with slightly lower elasticity; it is excess skin, a surface area larger than the volume it now covers, left behind when the fat beneath it shrank faster than the skin could contract or when age has reduced the dermis's ability to retract at all, and its fate is governed by the amount of weight lost, the speed of the loss, the person's age and their genetics, with slow, moderate loss in a younger person letting the skin follow and fast, large loss in an older person leaving laxity that no amount of recoil in the remaining dermis will take up. Every collagen skin trial enrolled weight-stable adults, mostly women between their mid-thirties and mid-sixties, with ordinary age-related facial skin, measured on the cheek; not one enrolled people after weight loss, not one measured skin on the arms, abdomen, thighs or neck, and not one measured laxity, excess or the quantity of skin at all. The instruments themselves could not have answered the question even if pointed at loose skin, because a cutometer measures recoil, how fast and completely a small patch of skin springs back after being pulled, and an abdomen with a fold of excess skin can have perfectly good recoil in every patch of it while the fold remains, since the problem is quantity and not elasticity; a few percent more spring in skin that there is too much of does not remove any of it. And the verb itself, tighten, like firm and lift, is cosmetics vocabulary under cosmetics rules, where a cream may claim a temporary surface effect, and it may not be used by a supplement, which holds no skin claim of any kind for collagen in the UK, the honest capsule carrying vitamin C's sentence about normal collagen formation for the normal function of skin and zinc's about its maintenance. So the sceptic's checklist returns two boxes of three: collagen really changes elasticity and hydration readings in ordinary facial skin at 2.5g and above over twelve weeks, and on loose skin it has never been tested and could not have tightened anything the instruments measure. The levers that do reach loose skin are the ones a lifter already knows: a slow rate of loss, around half to one percent of body weight a week, so the skin has time to follow; muscle built underneath it with resistance training, which fills some of the volume the fat left; protein at 1.6 to 2.2g per kilogram, which the dermis as well as the muscle is built from; sun protection and not smoking, which preserve the dermis's ability to retract; time, since skin continues to adapt for a year or two after a loss; and, where the excess is large, a surgical conversation, since significant excess skin is removed and not retracted. The worked example is the habit beside those levers, 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 2.5g the skin trials used, carrying vitamin C's and zinc's skin sentences and no tightening word. Does collagen really tighten loose skin: it really moves two instruments in ordinary facial skin, and on loose skin the box is empty.

What to check on the label