The barrier function is a scientific term for the outermost layer of your skin, responsible for keeping moisture in and damaging elements (like UV and free radicals) out. When the barrier function is working well, skin is hydrated, plump, and firm. But when it breaks down, overall skin health goes with it. So the key to skin health—and radiance—is a vital barrier function.
The Barrier Function, Briefly
The skin barrier—or stratum corneum—is what stands between us and the outside world, preventing environmental chemicals and biological irritants from entering skin, including free radicals, bacteria, other microbes, allergens, toxic chemicals, ultraviolet light, injury and other external assaults.
But that’s not all. It turns out that the barrier’s most important task is to prevent the escape of water from inside the body. The outermost layer of skin “is made up of multiple stacks of flattened cells or ‘corneocytes,’ each of which is encased in a thick coating of fat (or ‘lipid’),” according to UCSF dermatologists Peter M. Elias and Mary L. Williams.
Likening the stratum corneum to a brick wall, the stacks of cells are bricks and the fatty matrix surrounding them the mortar. Together they form a barrier that keeps skin’s precious water content inside, so skin stays firm, hydrated, and less prone to wrinkles.
How the Barrier Function Breaks Down
Despite all the heavy lifting it does, the barrier is delicate and prone to thinning with age. In fact, any assault on the stratum corneum—either from external damage or as a result of cellular water loss—can lead to sensitized and dehydrated skin that is susceptible to environmental harm, dryness, irritation, breakouts, sagging skin and other signs of aging.
Appearance, however, is just one reason to maintain a healthy skin barrier. Dry, flaky, itchy, irritated or sensitive skin are all common signs of a damaged or weakened barrier function. Damaged lipids in the mortar—from harsh detergents, physical harm to the skin, or environmental stress—cause the skin to lose water and dry out. And when skin is dry, it’s more permeable to irritants and allergens that trigger inflammation, which can lead to a host of issues, including rosacea, acne, eczema, and premature aging, among other things.
Maintaining the integrity of the protective barrier, then, is the secret to healthy, radiant skin. Take these steps to ensure the health of your barrier function:
- Minimize sun exposure by wearing hats and non-nano zinc oxide sunscreen.
- Avoid other outside-in attacks on the skin, including overzealous exfoliation, harsh soaps, chemicals and other pollutants.
- Support barrier function health with nourishing oils and strengthening serums.
Caring for the Skin Barrier
Whether skin is one week or 100 years old, the idea is the same: hydrated skin is resilient skin. And although we have to work harder as we age to maintain cellular hydration, moisture loss can be checked with the help of botanical oils that are high in essential fatty acids (EFAs)—including algae, passion fruit, baobab, and kiwi seed oils—which penetrate deep within the cells to bolster the body’s own moisturizing agents.
These antioxidant-rich oils work best in conjunction with molecules and other compounds designed to further support the health of your skin’s protective barrier. Here are three key ingredients to look for:
Keep an eye out for products that contain hyaluronic acid, a naturally-occurring molecule that helps maintain skin’s moisture. Hyaluronic acid is “a natural sugar in the skin that sits between skin cells and helps maintain hydration and skin plumpness,” Josh Zeichner, M.D., director of cosmetic and clinical research in dermatology at New York's Mt. Sinai Hospital, told Elle magazine. Its humectant properties enable it to hold onto “moisture by pulling in water to the skin like a sponge. As time goes on, the level of naturally occurring hyaluronic acid decreases—that’s why people's skin gets [drier] and sags as they get older. Adding it to your skin care regimen counteracts that fate.
You’ll also want to further support the health of your skin barrier by adding peptides to your skincare routine. Peptides are compounds that communicate a message to your skin that it has lost collagen and needs to manufacture more; in essence, topical application tricks the body into generating new collagen. The results of a study published in Skin Research and Technology on the effect of peptides administered to skin demonstrate that “treated areas show[ed] an increase in hydration and elasticity as a result of keratin peptide application.” They also “indicate that the keratin formulations reinforce the skin barrier integrity, improving its water-holding capacity.” Yet another report, this one in the International Journal of Tissue Reactions, establishes that the “application of the collagen-like peptide on the skin significantly reduced the total surface of wrinkles.” Researchers also note a “decrease in number and average depth of wrinkles.”
Then there are ceramides, waxy, fatty molecules found in skin that hold it together and help prevent moisture loss. (You can think of ceramides as the mortar surrounding the cellular bricks.) While young skin features ceramides in abundance, older skin manufactures far less. According to a review published in the American Journal of Clinical Dermatology, “most skin disorders that have a diminished barrier function present a decrease in total ceramide content with some differences in the ceramide pattern.”
As with lab-isolated hyaluronic acid and peptides, the news on the ceramide front looks promising. The report goes on to say that “formulations containing lipids identical to those in skin and, in particular, some ceramide supplementation could improve disturbed skin conditions.”
We can’t promise you the baby-smooth skin you had as an infant, but your body possesses many of the building blocks it needs to maintain a solid skin barrier. All it needs is a little help. Add a wide-brimmed hat, quality sunscreen, and supportive skincare to your toolbox and you’ll be well on your way to counteracting fate. At least when it comes to skin.
Shop this StoryOur Renew Pure Radiance Oil (filled with essential fatty acids) is clinically proven to increase skin hydration by 40.6% in 45 days. Add in the Renew Repair Serum (made with hyaluronic acid, peptides, and ceramides) and the result jumps to a 48.8% increase in facial hydration.
The Inside-Out of Skin, Peter M. Elias, M.D. and Mary L. Williams, M.D.
Natural moisturizing factors (NMF) in the stratum corneum (SC). I. Effects of lipid extraction and soaking. Journal of Cosmetic Science, Jan-Feb 2010
What Is The Skin Barrier, And Why Does It Matter? Peter M. Elias, M.D. and Mary L. Williams, M.D., June 2, 2015
Hyaluronic acid: A key molecule in skin aging, Dermato-Endocrinology, July 1, 2012
Dermatologists, Sun Bathing and Eczema, Peter M. Elias, M.D. and Mary L. Williams, M.D., February 5, 2016
Effects of moisturizing skincare on skin barrier function and the prevention of skin problems in 3-month-old infants: A randomized controlled trial, The Journal of Dermatology, January 2018
The usefulness of topical application of essential fatty acids (EFA) to prevent pressure ulcers Ostomy Wound Management, June 1997
Efficacy of a New Topical Nano-hyaluronic Acid in Humans, Journal of Clinical and Aesthetic Dermatology, March 2014
3 Reasons Why You Need Hyaluronic Acid in Your Skin Care Regimen, Elle, Nov. 25, 2015
Cosmetic effectiveness of topically applied hydrolysed keratin peptides and lipids derived from wool, Skin Research and Technology, May 2008
Collagen-like peptide exhibits a remarkable antiwrinkle effect on the skin when topically applied: in vivo study, International Journal of Tissue Reactions, 2004
Ceramides and skin function, American Journal of Clinical Dermatology, 2003
Skin diseases associated with the depletion of stratum corneum lipids and stratum corneum lipid substitution therapy, Skin Pharmacology and Physiology, 2015
The inflammation theory of disease, EMBO Reports, November 2012Essential Fatty Acids and Skin Health, Linus Pauling Institute, Oregon State University
Moisturizers: The Slippery Road, Indian Journal of Dermatology, May-June 2016