Elmer’s glue, Beyond Burgers, eau de toilettes: I love ‘em! Use ‘em! Trust ‘em to be safe and good! But, uh… I’m still not totally 100-percent on what they are. In the skincare world, maybe that describes your relationship with ceramides. You know they’re great—for sensitive skin, for sensitized skin, for skin that’s breaking out or wrinkling or just needs a little general help. There’s a good chance one (or more!) of the skincare products you’re using right now lists “ceramide” on its ingredient list. But even a beauty editor might scratch their salt-scrubbed head if you put them on the spot for a definition. If you’re looking to know more, you’ve come to the right place.

Where can I find ceramides?

In everything from cleansers, to serums, to essences, to moisturizers, and beyond. You can also find ceramides occurring naturally in skin.

My skin?

Yep, your skin. Your body’s constantly getting rid of things it doesn’t want anymore: carbon dioxide when you breathe, water and acid when you pee, debris when you sneeze. And at the microscopic level, your cells have their own waste management system. As cells generate energy for your body, they dump anything that would gum up the works if it hung around. Ceramides are just one type of molecule that gets the boot.

Cell waste products serve a new purpose once they’re excreted: squeezed between the teeny tiny spaces between cells, they essentially form mortar to hold the cells in place. “When cells aren’t as densely packed, your skin becomes vulnerable to conditions such as atopic dermatitis, psoriasis, and loss of elasticity which may cause wrinkles and sagging,” explains Joyce de Lemos, lead chemist for Dieux Skin. In addition to keeping your cells in place, this mortar (its official name is the extracellular matrix, BTW) is filled with oily fatty molecules that form a physical barrier from the outside world. This keeps irritants out, but it also helps keep moisture in. “The barrier prevents water from evaporating out of the skin,” says de Lemos, which is key for skin that feels plump and moisturized. Maria Giovanna Bruno, a chemist from the ingredient manufacturer Roelmi HPC, adds that the extracellular matrix also helps cells communicate with each other—signals sent through it act like a conductor for the orchestra of cell death, shedding, and renewal.

What’s the extracellular matrix made of, exactly?

If you were going to whip up some extracellular matrix in a kitchen, important ingredients would be fibrous proteins like collagen and elastin, enzymes, and oily molecules (called lipids) like fatty acids, cholesterol, and, of course, ceramides. This is some good stuff! Each component plays a role in healthy, moisturized skin. However, the composition of your extracellular matrix isn’t static throughout your entire life. “As you age, the composition of your extracellular matrix changes and the percentage of ceramides, cholesterol, and free fatty acids within the skin diminishes,” says de Lemos.

When your natural ceramide levels start to lower, or your barrier is compromised because of external factors like sun damage, stress, or using too many strong skincare products, you can replenish them with topical application. Topical ceramides strengthen your skin barrier and get your skin running smoothly again (read: less sensitivity and an improved look of fine lines).

Quick question.

What’s up?

Why do you keep writing “ceramides” in plural? Does that mean there’s more than one of them?

Actually, yes! “Ceramides” refers to a whole category of fatty-acid molecules with the same basic layout. “There are many ceramides with slight structural differences,” explains Bruno, citing ceramide NP, ceramide NS, and ceramide EOS as some you might have seen on labels before. Way more ceramides exist than it makes sense to list here. But luckily, you don’t need to keep track of them—all ceramides will be identifiable by the word “ceramide” on a label, and they all basically do the same thing for your skin.

What’s the difference between different ceramides?

Mostly, it comes down to price and compatibility—two things you don’t really have to worry about unless you’re a cosmetic chemist. “Ceramides can range in price from a couple thousand dollars per kilo to almost 100 thousand dollars per kilo,” explains de Lemos, which is a huge discrepancy brands need to consider when they’re working on a formulation. Where a ceramide comes from is the main determinant of price. Most brands either use ceramides that come from plants or were created synthetically in a lab—Bruno notes that plant-derived ceramides are often more expensive than synthetic ones, though both options are vegan and biomimetic.

For chemists, what’s worth the splurge? Compatibility. “Ceramides are notoriously hard to incorporate into formulations,” says de Lemos, who adds that ceramides’ supercharged ability to hold together skin cells also means they’re not the most cooperative when chemists try to mix them into a formula with other stuff. A more expensive ceramide on an ingredient list might mean that whatever else is in the product just wasn’t meshing with the cheaper options. Because of this, it’s not necessarily a one-to-one relationship between a higher price point and better ingredient quality—it’s more about the brand finding the right balance in its budget. Whatever you’re buying is guaranteed to already be in that sweet spot.

In that case, what should I be looking for?

Both chemists emphasize that looking at a formula holistically is a lot more important than fixating on an ingredient list. “To select a product solely based on one or some of the ceramides in it would be like choosing to eat a cookie because you like one of the ingredients in it, like flour,” explains de Lemos. “While it’s good to know what ingredients you like and don’t like, it’s also important to assess the taste of the entire cookie.” Ceramides work really well with other moisturizing ingredients, like cholesterol and fatty acids, and even better in certain ratios with these ingredients. (This study suggests a ratio of 3:1:1, for example.) You might also look for formulations that use multiple kinds of ceramides—a diverse profile can help round out whatever ceramides you might naturally be lacking.

Anything else?

De Lemos also suggests shopping from brands who’ve done clinical trials on their product (if not provided on a brand’s website, Googling the product name plus "Pubmed” is a good way to easily see if clinical trials are available for public review). And finally, you should always look for a product you like and can afford to replenish. Unlike a treatment serum or a mask you might only need sometimes, ceramides are an integral part of a routine that supports your skin’s natural function! You’re going to want to keep them around.

—Ali Oshinsky

Now that you’re in the know, let’s shop:

Photo via ITG