Unfortunately, putting collagen creams, lotions, serums, masks or what-have-yous on your skin will not help replace your skins collagen. But why?
The 500 Dalton Rule
Molecules (whether they're collagen, or whatever) need to be small enough are to penetrate through the layers of the skin and be absorbed. As a guideline, this limit is often cited as 500 Daltons. In fact, this guideline is so well known that often cosmetic chemists and dermatologists refer to this as "The 500 Dalton rule". Now there are exceptions to the rule, but generally, the reason why 500 Daltons rule is generally accepted is because: 1)almost all common contact allergens are under 500 Daltons. Larger molecules cannot penetrate the skin and cause allergies; 2) the most commonly used pharmacological agents applied topically are all under 500 Dalton; 3) all known topical drugs used in transdermal drug-delivery systems are under 500 Dalton.
A useful corollary of the 500 Dalton rule is that the next time, if you get some marketing spiel trying to brainwash you into buying their "natural" products on the grounds that "the chemicals you put on your skin are toxic and will enter your organs and blood through your skin" (sounds crazy, I know, but some parts of the internetz are pretty aggressive about this point of view), then you can call their bluff, because by and large, most molecules as found in skincare (both the natural and "chemical" variety) are much larger than 500 Daltons. Truth is, very little in skincare penetrates our skin. If it did, it wouldn't be a cosmetic anymore - it would be a drug, and would be subject to stricter regulation. But let's get back to collagen!
Applying the 500 Dalton Rule to Collagen
So how does this 500 Dalton rule help us understand how collagen in skincare works? Collagen (including collagen "extracts" in skincare) has a molecular weight of 15000 to 50000 Daltons, so they are waaay bigger than the 500 Dalton limit needed to ensure that they will pass through and be absorbed by the skin. Some products advertise that they have "smaller collagen" that will be able to be absorbed by the skin, but this is just not the case. In fact, when I tried to look up exactly what these manufacturers meant by "smaller", the best I could find was collagen in the range of 2000 Daltons and up, which still isn't going to penetrate your skin. The truth is, it's all a marketing play, as there is no real benefit from collagen applied topically - it doesn't get absorbed into your skin, but it just sits on top of your skin.
So, if collagen doesn't actually penetrate your skin, then what does it do when you apply it to your skin? Well, firstly, collagen on top of your skin can function as a humectant, and this helps to moisturize your skin. But there are a lot of other equally cheap and effective humectants out there, such as glycerin and urea. So you don't really need to spend all that money putting collagen on your face when any old cream with glycerin would do the trick.
Secondly, the collagen in some creams also form a film on the skin that gives the appearance of smoother skin by filling in surface irregularities. Such creams that have this effect on skin are typically also formulated with other proteins/peptides in them to enhance the film-forming effect. But, as you might guess, this is a temporary effect - it's gone as soon as you wash your face, and wash the film off. It definitely does not have any long-term effect.
Even if somehow you managed to get some collagen from your skincare into your face (I don't know how that would be possible, but assuming somehow that hypothetically it happened), it still wouldn't work. This is because it would not be able to incorporate itself within the complex collagen structure in the skin. Collagen in your skin doesn't exist in isolation - it's not like you have individual bits of collagen floating around in your skin and somehow stuffing more collagen into that space will help to plump it up. Collagen is actually part of a larger structure within the dermal layer of your skin, which includes other important components, such as elastin, hyaluronic acid, and so on. The collagen fibres in your skin are "woven" in a wickerwork pattern (yes, like the baskets), which gives them mechanical strength. So any collagen that might pass through your skin will still not be incorporated into the pre-existing structure. As an analogy, if you had a shirt with a hole in it, and you tried to patch the hole by putting a bunch of broken up threads on top of the hole, it wouldn't work. The same thing applies to trying to "fix" your skin with collagen.
The wickerwork structure of collagen in your skin. This is an actual closeup photo of collagen in your skin! (Source: Tissue Mechanics, by Cowin & Doty.)
If in fact you did want to help collagen synthesis within your skin, there are other things you could apply to aid this process that have scientific literature to back up their efficacy (Vitamin C or ascorbic acid, retinoids, and niacinamide are just a few examples), but applying collagen simply isn't one of them.
What About Eating Collagen?
When I tell most of my friends this, they immediately follow up by exclaiming, eureka-moment style, "Oh! So I should be eating collagen supplements instead of using collagen creams!" Oops. Unfortunately, eating your collagen won't work either. It might be tempting, though - there are so many, many brands of collagen out there - Fancl, DHC, Meiji, the list goes on. And they all advertise themselves oh-so-scientifically:
What happens when collagen is ingested? Well, collagen is really a type of protein, and all proteins are composed of amino acids. So, collagen (like any other protein) gets broken down into amino acids, and thus they don't jump straight undigested from your stomach to your skin. So unfortunately, while such products claim to replenish the collagen in your skin with collagen that you eat, the truth is, once you eat it and start off the digestion process, by the time your small intestines absorb it, it's broken down to amino acids, just like any other protein. This is where a little bit of science can help a long way. Everyone knows that if you eat a piece of steak, the steak will not end up under your skin wholesale in exactly the same form in which it was eaten. So why do we believe that when we eat collagen supplements (tablets, powders, whatever), it will end up in our skin as collagen in the form that was eaten? The truth is, both the steak and the collagen supplement are digested in the same way at the end of the day - into amino acids your body uses for a variety of uses. But we fall for the marketing (did you see the picture above, man? That's some hardsell tactics!), and it is combined with a simplistic and seductive but flawed logic (collagen in = collagen out), and this combination makes us leap to the wrong conclusion.
How protein is digested in your body - this applies to both the steak, as well as collagen. (Image source)
Also, you can get your amino acids from plenty of other protein-rich foods - meat, dairy, beans, tofu - you know, actual food. There's no need to spend extra for collagen supplements. While they're not harmful, there's probably no extra benefit you're going to get from them - you supply your body with amino acids, but it's not like you can't do the same through a healthy, well-balanced diet. Besides, collagen supplements aren't cheap, and there's a much cheaper alternative available. If you do want to eat collagen, instead of splurging on a collagen supplement, you can eat gelatin - it's cheaper, and is what collagen supplement and skincare marketers have been calling "hydrolyzed collagen" (aptly called because gelatin is in fact formed from the hydrolysis of collagen). This is why companies such as PB Gelatin, Nitta Gelatin and Rousselot Gelatine, which manufacture gelatin for the food and pharmaceutical market (in the pharma industry it's sometimes used as a coating material for capsules and the like), are also able to manufacture a line of collagen for supplement use. It's because they're pretty much the same thing. So, instead of eating collagen, you could just eat gelatin, it's definitely cheaper, and possibly yummier too (who doesn't love jello? I love me some jello!).
If you need a collagen supplement, you may as well eat this. (Image source)
But my Collagen Supplement is FDA Certified! It Must Work, Right?
Explaining this fact of digestion to some of my friends might sometimes make them confused. They might then ask, "But I saw XYZ MAGIC BRAND of collagen supplement was 'approved by the FDA' or 'FDA certified', so it must work, right?" Once again, a little knowledge will help here. Contrary to popular belief, the FDA does not regulate supplements of any kind. Let me repeat that: The FDA does not regulate supplements. The FDA's does in fact do tons of regulation, but it is primarily for medical implantables and medical equipment (so things like pacemakers, stents, X-ray machines, physiologic monitors, and hand-held surgical instruments), and for drugs, both the prescription drugs, as well as OTC drugs (like anti-dandruff shampoo). These types of products do require their manufacturers to carry out tests to prove that the product is safe for use and is effective, depending on the classification of the product (invasive products go through more rigorous testing than non-invasive ones, and prescription drugs go through more rigorous testing than OTC products).
Stuff the FDA actually regulates. Supplements, however, are not under FDA regulation. (Image source)
So now, what about supplements? Like I mentioned before, the FDA does not regulate any of them. Not collagen supplements, not vitamins, not herbs, not anything. In fact, let me quote directly from the FDA website: "a firm is responsible for determining that the dietary supplements it manufactures or distributes are safe and that any representations or claims...are not false or misleading. This means that dietary supplements do not need approval from FDA before they are marketed." And again, also from the FDA website: "Dietary supplements are not (Italic emphasis theirs) approved by the government for safety and effectiveness before they are marketed. If the dietary supplement contains a NEW (all-caps also theirs) ingredient, that ingredient will be reviewed by FDA (not approved) prior to marketing — but only for safety, not effectiveness." (If you want more on this topic, this LA Times Healthy Skeptic Column article is a pretty useful overview.)
So how does this info relate to collagen supplements? Since collagen supplements are classed not as a drug, but as a supplement, it means that 1) the company making the collagen supplement does not need for it to be approved by the FDA before selling it on the market, and 2) even if there is some new ingredient, the ingredient is only reviewed for safety (i.e. FDA will ensure that it won't kill people or make people sick), not efficiency (i.e. FDA will not ensure that it will actually work to cure baldness, grow hair, or replenish collagen). So while companies selling collagen supplements (or any other kind of supplements, for that matter,) like to claim that they are "FDA certified" or "FDA registered", it's really a marketing sleight-of-hand that is intended to make the consumer think that the FDA has somehow verified that their product works, when they really don't. And of course, if a company claims that their supplement is "FDA approved", then they are just not being honest at all, since FDA doesn't approve supplements to begin with. We have already seen that collagen supplements are really just broken down into amino acids in the body, just like any other protein. A company claiming FDA certification isn't going to change how your digestive system works on ingested collagen.
Sudden Clarity Clarence has also just had an epiphany.
Conclusion: Nope, You Don't Need It!
Anyway, I hope this has helped provide a sanity check on some of the hype around collagen skincare and supplements. Most of these are really marketing gimmicks and not much else. Instead of spending money on these creams and supplements that don't work, it might be wiser to spend money on a good sunscreen instead, because UV exposure is definitely one of the major contributors to aging! Since I'm something of a skincare nut, I do also have a post on sunscreen tips and information you should know, but if you want to see me put some of these principles into action, though, you can also check out my review of a collagen supplement here.