If you turn on your TV or open any beauty magazine, odds are you’ll come across an ad for the newest anti-aging cream, featuring models with impossibly smooth faces and long lists of chemicals.

These ads sound misleading and, don’t get me wrong, some of these so-called “anti-wrinkle” chemicals are just marketing buzzwords. But it turns out that a few of them might actually help protect your skin from damage.

Your skin is like a layer cake, and the icing on that cake is a thin layer of cells called the epidermis. The epidermis is supported by the dermis, which is where you’ll find nerve endings, sweat glands, hair follicles, and connective tissue.

Connective tissue is made up of a mix of cells hanging out in an extracellular matrix, which contains some specific molecules that give your skin some structure and help with things like healing wounds.

One is collagen, a really plentiful protein that helps cells stick together and makes your skin stronger. There’s also elastin, a protein that gives your skin the ability to bounce back when you stretch it. Then, there are long chains of sugars called glycosaminoglycans or GAGs, which act like sponges and can hold huge amounts of water.

They help resist squishing forces on your skin and keep it hydrated and healthy-looking. As you get older, the production of these extracellular matrix molecules naturally starts to slow down. With less structural support from the dermis, your skin starts to look thinner and build up wrinkles.

So we still haven’t discovered a fountain of youth to fight against biochemical aging, but the biggest cause of wrinkles isn’t getting older, it’s environmental damage, like from the sun. Sunlight contains three types of UV radiation, including one that never quite gets through our atmosphere. That leaves two that affect our skin.

Spending time outside is actually good for your skin, in small doses. UVB radiation interacts with a molecule in your skin that gets turned into vitamin D, which you need to absorb calcium and keep your bones strong. But too much UVB causes damage to your cells’ DNA, leading to sunburn and ultimately skin cancers.

Lots of UVA radiation is also not great for you, because it interacts with other molecules in your skin to create reactive oxygen species. Reactive oxygen species include things like hydrogen peroxide, nitric oxides, and unstable molecules called “free radicals,” the rebellious teenagers of the molecular world.

Electrons love travelling in pairs and are most stable that way, but free radicals have unpaired electrons. Because of their instability, free radicals are on the hunt for more electrons and will take them from things like DNA, proteins, and fats—reacting with those molecules and damaging them in the process. And that includes molecules in the dermis like elastin and collagen, creating tangled clumps or breaking them down. Your body can generally deal with some damage, but too much, and you might have a wrinkly problem.

There are tons of anti-wrinkle creams on the market, but the chemicals that have been shown to work actually deal with skin damage. Retinol, also known as vitamin A, and chemically related compounds called retinoids have been shown to reduce wrinkles and to speed up the healing of cuts and scrapes—as long as you follow recommendations by dermatologists.

Using retinoids and then exposing your skin to sunlight or using them while pregnant, for instance, can cause more damage because of how they interact with your cells. And you don’t want that. When you slather certain retinoids on your face, they can interact with different receptors on skin cells, and with DNA to activate certain genes. Biochemically, this can tell repair mechanisms in your skin to speed up, so you get rid of stuff that was damaged by reactive oxygen species and make new cells and molecules at a faster rate.

So retinoids can help maintain the structure of your dermis and fight off wrinkles by making your body produce more collagen, elastin, and GAGs. And they seem to be the most effective ingredient in anti-aging creams.

A few other compounds have been found to have similar, but less potent, effects. Chemicals like salicylic acid, for instance, might also activate genes that cause cells to make more collagen, or boost certain repair pathways. And hyaluronic acid is a GAG, and can help retain moisture. But there are also lots of chemicals in anti-aging creams that are probably just... junk.

Take anything with peptide in its name, which just means it’s a smaller building block of proteins. It’s true that peptides are involved in lots of processes in your body, including making new cells and proteins, which are important for your skin’s structure. But many dermatologists think that most of these anti-aging peptides are just too large to squeeze in between cells in the epidermis, so they probably just sit on top of your skin and do nothing.

And despite all those expensive marketing campaigns, the best way to fight off wrinkles might just be blocking UV radiation to protect your cells from damage in the first place. So the best anti-aging cream you can buy is probably just sunscreen!

Thanks to Patreon patron Patrick Gilmore for asking this question, and thanks to all our patrons, whose support lets us keep making SciShow! If you want to learn more about skin damage, we have a video where Hank explains why sunburns happen. And don’t forget to go to youtube.com/scishow and subscribe!