What is the Skin Barrier?

By: Elena Chaikin


“Replenish your skin barrier,” “Repair damage in your skin barrier,” “Improve your skin barrier.”

We often hear these phrases and more about skincare.


But what do these mean? What is our “skin barrier”?


Anatomical structure of the skin. Elastin, Hyaluronic acid, Collagen. Infographics. causes of wrinkles on the skin. Vector illustration on isolated background

Our skin is the largest organ in our bodies. It helps protect everything inside us. The skin can be split into three general layers: the outer layer called the epidermis; the middle layer, called the dermis; and the third, innermost layer, which is called the subcutaneous (or hypodermis) layer. The outer layer has two major sections itself —the surface, a thin, slightly acidic layer of oils (called sebum) and sweat; and the actual layers of cells below, which is the skin barrier. Imagine it as a wall of bricks.

A healthy, functioning skin barrier keeps your body protected against pollution, toxins and irritants, and keeps the lower skin layers from losing water. The part right at the top of our epidermis, under the layer of sebum, is formally called the stratum corneum. There are 10 to 30 layers of tough protein cells that are called corneocytes, which are stuck together by lipids. These cells naturally slough from our bodies and are continually replaced by the cells underneath them in the epidermis. But the epidermis has to be kept healthy in order to replenish the corneocytes.

These lipids include cholesterol, fatty acids, and ceramides. Without them holding the corneocytes together, toxins and pathogens from our environment would penetrate the skin and cause bad effects inside our bodies. So, the skin barrier is one of our bodies’ first lines of defense. It controls water loss, retains moisture, and keeps your body hydrated. If your skin barrier isn’t maintained, it will be prone to damage, including water loss, aka dehydration. Have you ever lightly skinned your knuckle or finger (so that it doesn’t bleed) and then seen a small pool of fluid form on your skin? You knocked the stratum corneum off.

Signs of a damaged skin barrier include dry, itchy, or flaking skin that might be sensitive, red, and inflamed. A weak barrier will leave the second and third layers of the skin prone to injury.


How can the Skin Barrier be damaged?

Skin barrier

Daily, our skin is confronted with threats from our environments—dry environments (especially during winter), or even environments that are too humid; irritants such as air pollutants or allergens; products that we may use on our bodies, such as soaps; or detergents that we use to wash our clothes; harsh chemicals that we clean with; and sun exposure to name a few.

We can also put our skin barriers at risk by too much exfoliation, doing too many skin peels, or even over-washing. That squeaky clean feeling after you wash your face? Don’t leave your skin that way. Following a skin routine will bring your skin back to its normal pH level and return moisture with creams. You can also damage your skin barrier if you use water that’s too hot, or if you change too many products in your skin routine.

Also, topical steroids that doctors may prescribe us will cause our skin to get thinner if they are used for too long. And some people may have genetic conditions that will affect their skin, such as atopic dermatitis and psoriasis.


The Sun

The sun is a double-edged sword. Sunlight, or solar radiation, contains heat (infra-red radiation), visible light, and ultra-violet light (UV radiation). On one hand, the UV radiation helps our skin produce vitamin D, essential to our bodies. On the other, UV radiation is what causes sunburn and is responsible for most of the skin cancer cases across the world. There are three types of UV radiation: UVC which is filtered by the ozone layer in the sky; UVB, which is absorbed by the epidermis, and UVA, which penetrates both the epidermis and the dermis.

Even low levels of UV radiation will cause damage. That is why experts recommend that you still use sunscreen on a cloudy day, if you’re inside a building and there are lots of uncovered windows, or driving your car. While most UVB radiation is blocked by window glass, UVA radiation passes through it, and is responsible for significant damage to your skin.

Damage to the skin barrier happens because UV rays affect the proteins in your skin cells, the corneocytes. The UV rays break down skin cells, oxidize the lipids holding them together, and damage DNA. Redness and burning are usually the immediate effects from the sun, while sped up aging (fine lines and wrinkles, even dark spots) are some of the later effects of sun exposure.


UV Rays

UVA and UVB rays could account for 80% of skin aging, including increased dryness, wrinkling, increased pigmentation, and photoaging. Collagen is a building block for many parts of your body: bones, skin, hair, muscles, just to name a few. Naturally with age, the collagen in our bodies decrease. Collagen is an ingredient in skincare that is often mentioned because it is what keeps skin plump and youthful. However, skin, unprotected from the sun, will lose its collagen faster, giving way to premature wrinkles and decreasing skin elasticity.

The worst effect from the sun is, of course, skin cancer, which is caused by DNA damage. UV rays create free radicals (unstable molecules) that break down the collagen, healthy skin cells, and ultimately lead to cell damage. The cells malfunction and this causes them to multiply and replicate too much.

The sun’s UV rays also damage fibers in your skin called elastin. Elastin is often confused with collagen. Collagen provides the skin with structure and support, while elastin gives skin stretch. So, when elastin fibers breakdown, your skin loses its ability to snap back in place to its original shape and will also take longer to heal. Luckily, using sunscreens and other sun protection options will help prevent these unfortunate results from sun exposure.


How to maintain a healthy skin barrier?

Young Woman Applying Cream On Her Face Over White Background

You’re now an expert in what can cause skin barrier damage, but the next step is learning how to prevent it. Let’s start with skin routines, as it will be one of the most effective ways to repair and support your skin barrier. If you don’t have a skin routine, starting simple is the best way. A gentle facewash, which you should use in the morning and night, followed by a serum, which can also be specific to repairing and improving the skin barrier, and lastly a moisturizer. Serums are great because you can give your skin an added treatment that can be for hydration (there are different kinds that are targeted for different skin concerns; you can even look for serums that specifically mention the skin barrier).

As mentioned before, over-exfoliating with scrubs or skin peels can damage your skin. You will know if you have over-exfoliated your skin if it is red, sensitive, or stinging. It could also be dry and/or flaky. You might feel that your skin is tight. If you’re acne-prone, you may have increased breakouts since a damaged skin barrier means bacteria and other toxins can get through. If you have dry skin in general, extra hydration is key to maintaining a healthy skin barrier. You can include simple oils such as jojoba oil or rosehip oil in your routine. Squalene oil, in particular, is very popular nowadays. Or you can find products that contain these oils already. Just stay away from oils that are fragranced, as fragrance can irritate skin and even cause breakouts.

Since one of the lipids that hold together the corneocytes in our skin are ceramides, moisturizers that contain ceramides are a very effective choice to include in your skincare routine! Not only are skincare products containing ceramide great for dry skin, but ceramides are also especially great for acne-prone skin because acne leaves skin red and dry. But there are other great active ingredients.

Beautiful girl choosing beauty products from the bathroom cabinet

Hyaluronic acid is another popular ingredient in skincare because it’s a humectant—a substance that draws moisture into the skin. Working in conjunction with ceramides—which will mimic the natural ceramides found in your skin—hyaluronic acid will pull water from the upper layer of skin, the dermis, further into the epidermis. Old-school petroleum jelly also works by creating a layer over the skin and keeping moisture in. This technique is a recent K-beauty trend known as “Slugging.”

Another important skin factor to take note of is that we must balance the pH of our skin, which can be tricky. The skin barrier has a slightly acidic pH at around 5.5. It is very possible to throw that number off, which will disturb the natural ecosystem of our skin. When looking for skincare products, you can keep an eye out for those that mention “pH balancing.” When considering cleansers, remember not to use regular, classic soap as it’s too alkaline. Never use regular soap to wash your face!

There are some things that you should keep in mind while discovering what skincare you’ll need. Not all ingredients and products work for everyone, so you should try different kinds and see what works best for you. If you’re uncertain, you can consult a dermatologist or esthetician and get the exact knowledge about your skin and which products will work best. A dermatologist also has the authority to prescribe you medications if you need them.

In addition to skincare, there are lifestyle choices that will help your skin in general. Stay hydrated. Eating healthy foods that are rich in antioxidants is also important. Foods that are good for your skin include carrots, and other yellow or orange foods; green, leafy vegetables, tomatoes, berries, beans, and nuts; and in terms of protein: fish because fish oil will help promote good skin elasticity. Blueberries, pomegranates, and other fruits and vegetables that are rich in vitamin C—are full of those antioxidants.



Three molecules inside the human cell: Free radical with missing electron, Normal stable molecule with paired electrons and Antioxidant with extra electrons which can be donated to free radical

Antioxidants are important to consume through food, and they are also important for your skin. Why are they so great? They have the ability to halt the chemical reactions that may damage skin cells. Those free radicals mentioned earlier—antioxidants actually adsorb them and neutralize them, preventing them from wreaking havoc. Skin damage due to free radicals will lead to inflammation, which keeps cells from working properly and repairing themselves.

Think of antioxidants as defenders for our bodies. They can do many miraculous things: such as improve signs of aging, prevent sun damage by stopping your skin’s inflammatory response to sunrays, which prevents sunburns, and give protection against sun damage and photoaging. The list goes on—antioxidants can even help skin cells repair themselves.



Let’s look at the most important and clinically proven antioxidants many of which also have other beneficial effects as active ingredients:

        Vitamin C (also called ascorbic acid) has many vital functions inside your body. It is needed for blood vessels, cartilage, muscle, collagen, and more. Being a powerful antioxidant, it neutralizes free radicals, whether they are from tobacco smoke, UV light, or X-rays. It also boosts your immune system and fights diseases such as heart disease, cancer, eye diseases, and even the common cold. Have you been told to take vitamin C when you’re sick or when you feel a cold coming on? It won’t prevent the common cold, but it can control symptoms and maybe even shorten the span of the cold. Since our bodies don’t produce vitamin C, we need to eat foods that contain it or take supplements available over the counter.

For skin, vitamin C works by fighting free radicals. It helps protect from sun damage, reduces signs of aging, and can improve your skin’s entire appearance. Vitamin C stimulates collagen production, which as mentioned before promotes a youthful appearance to your skin. Adding vitamin C, whether in serum form or already in a moisturizer, to your skincare routine (preferably used in the morning before adding your sunscreen) is a great option.

        Vitamin E is another amazing antioxidant and is generally considered the most powerful antioxidant. In our bodies, Vitamin E helps to protect cells from free radicals found in our environments. Overall, our bodies need vitamin E for our immune systems, as it can help fight bacteria and viruses as well as keep our blood from clotting.

Applied topically, vitamin E fights free radicals. Protecting the skin barrier, it works in two ways: as a humectant (attracting water) and as an emollient (trapping water). Among other great benefits vitamin E provides, it helps to relieve eczema and reduce scars and stretch marks. It’s a natural anti-inflammatory, soothing and calming skin. It comes in oil, creams, and serum versions. Overall, vitamin E is a great moisturizer for your whole body.

        Retinol is a form of vitamin A and part of a family of ingredients called retinoids—which are actually considered antioxidants. Retinol was first used for acne, which it is still great for. Nowadays, it is marketed as one of the best ingredients for aging skin. You can get it over the counter in various skin care products and from a dermatologist for more potent uses. Retinol works deep in the skin, promoting the production of collagen and elastin. It is highly recommended that you use any type of retinol at night, as it will make your skin sensitive to UV rays.

        Niacinamide, which is vitamin B3, is amazing for improving skin texture and fine lines, soothing acne breakouts, and for your skin barrier.

        Resveratrol, which comes from grapes and is known for its anti-aging properties, is great for inflammation, has antibacterial and antifungal properties, and helps keep skin free from infections.

These antioxidants and active ingredients all have one major problem: They are susceptible to photodegradation in the sun and break down rapidly if not protected.


Improving Antioxidant Performance

Ferulic Acid and Feruloyl Glycerides. 

One way formulators of cosmetics use to protect these molecules from photodegrading is to recommend consumers to use a sunscreen, or formulators use an SPF booster to help preserve their properties. You may have seen “ferulic acid” or “feruloyl glycerides” in the ingredients list of your products. These molecules are antioxidants in their own right but also provide additional protection.

        Ferulic Acid. Ferulic Acid is an antioxidant that has many benefits for your skin. Ferulic acid is found in plants and is one way that nature uses to protect plant cells from the damaging effects of the sun and other pollutants. Not only does it have anti-inflammatory and antimicrobial properties, but it is also a free radical scavenger that reduces signs of aging when used in cosmetics. Unfortunately, ferulic acid is difficult to formulate in cosmetic products since it is not soluble in either oil or water.

        Feruloyl glycerides. More recently, a new advanced form of ferulic acid has been developed that is easier to formulate and has enhanced properties. Feruloyl glycerides have a ferulic acid attached to an oil such as soybean oil, coconut oil, or hemp seed oil. This powerful ingredient combines the amazing properties of ferulic acid with the formulation advantages of natural oils. Researchers have shown that feruloyl glycerides are rapid antioxidants (1), and have strong broad-spectrum UV absorbance (2).   Feruloyl glycerides are also “photoprotectants” and protect other active ingredients in skin care products such as Vitamin C and Vitamin E from being damaged by sunlight (3).  Furthermore, when combined with sunscreens, feruloyl glycerides have the ability to increase the SPF of the sunscreen product. Feruloyl glycerides were initially developed at the USDA’s National Center for Agricultural Utilization Research (NCAUR) in Peoria Illinois*. They are now produced as FeruliShield™ products by the Midwest Bioprocessing Center.


More information on feruloyl glycerides.



Peer-reviewed Research Paper References

  1. Compton, D. L., Laszlo, J. A., & Evans, K. O. (2012) Antioxidant properties of feruloyl glycerol derivatives. Industrial Crops and Products, 36:217–221.
  2. Compton, D. L., Goodell, J. R., Evans, K. O., & Palmquist, D. E. (2018) Ultraviolet absorbing efficacy and photostability of feruloylated soybean oil. Journal of the American Oil Chemists’ Society, 95:421–431.
  3. Compton, D.L., Evans, K.O., Appell, M., & Goodell,   (2019) Protection of Antioxidants, Vitamins E and C, from Ultravoilet Degradation using Feruloylated Vegetable Oil. 2019.  J Am Oil Chem Soc.


Other References




*Mention of trade names or commercial products in the referenced publications and in this document is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the United States Department of Agriculture (USDA). USDA is an equal opportunity provider and employer. Research was supported in part by the U.S. Department of Agriculture, Agricultural Research Service.

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