The ESK blog
Skin barrier: a deep dive into understanding the skin barrier
20 April 2024
Dr Anne Thomson
If you’ve been here for a while, you’ve no doubt heard us bang on about the skin barrier. And if you’re new here, welcome! You’re about to learn exactly what and where your skin barrier is, why you need to protect it, what can damage it and how to repair it.
What do we mean by skin barrier?
The skin is our largest organ, making up about 15% of our body weight. Obviously it keeps our insides in and the outside world out, but is so much more than just a bendy suit of armour. Whilst there is a definite physical component to the skin barrier, just as important is the way the intricate web of delicate structures and biochemicals act and interact, both with each other and the outside and inside worlds. This is known as the skin barrier function.
There are four main components of the skin barrier: physical, chemical, microbiological and immunological – all of which work together. Changes in one of these, will affect all the others.
Whereabouts in the skin is it?
The skin is made up of 3 main layers:
- The hypodermis (below the dermis) is the fatty layer, which cushions the underlying muscles and bones and provides insulation to help with body temperature regulation.
- The dermis is the thickest layer of the skin and is where the skin “appendages” are, things like hair follicles, sweat glands, oil glands, nerve endings and blood vessels. Collagen and elastin are produced here giving the skin its strength and stretch. The dermis also provides precursor chemicals, support and nourishment for the outer layer, the epidermis.
- The epidermis is the outermost layer and is also the thinnest. It has 5 levels of its own, the most important of which, for the skin barrier at least, is the stratum corneum.
The stratum corneum (SC), skin barrier HQ!
This is the outermost layer of our outermost layer. It’s also the bit we see – when things go wrong with the skin barrier, this is where we notice it.
The SC is arranged in a “bricks and mortar” structure, which is kind of what you’d expect of a barrier, much like a wall. The bricks are flattened skin cells (aka corneocytes) which are held together by the mortar, a lipid (fat) layer which, among other things, acts as a two-way barrier to moisture, preventing moisture loss from the inside (known as transepidermal water loss or TEWL) and stopping water and other nasties from getting in.
There are 3 main lipids that are crucial to this layer: ceramides (which make up 50%), cholesterol and free fatty acids. Also in here are peptides like fillagrin and natural moisturising factor (NMF), which help lock in moisture, maintain an acid pH and protect against UV radiation.
pH of the skin
Your skin is covered in important microbes that create what we call your protective acid mantle. This acid skin environment helps to maintain your skin barrier which is how it plays a major role in keeping out irritants, germs and allergens.
Immune system and the good bugs
The SC also interacts with the immune system via complicated signaling processes to help ward off infection and promote wound healing. The skin’s good bacteria play a major role in this.
So what happens when things go wrong with the skin barrier?
Plenty! Skin barrier dysfunction is implicated in many well-known skin conditions such as atopic dermatitis (eczema), rosacea, psoriasis, acne, dry skin, sensitive skin, ageing skin and hormonal skin.
What causes disruptions to the skin barrier?
There are a ton of things which can upset the delicate balance, including:
What are the signs of an impaired skin barrier?
One of the ultimate goals of the skin barrier is to maintain hydration, meaning early signs of barrier problems include dryness, flaking, the skin feeling tight or even cracked.
Inflammation can quickly follow with redness, itching, break-outs and flare-ups of acne, rosacea, eczema and sensitivity.
Often at this point, we start throwing stuff at the problem which can make it worse! Common mistakes include:
- Over-cleansing, especially with (gasp!) soap-based cleansers
- Over-exfoliating with (gasp again!) physical scrubs or the wrong strength hydroxyacids
- Ineffective moisturisers that contain irritants, don’t contain the right active ingredients or are at the wrong pH
How to heal and repair your skin barrier
- Recognise the signs and act early
- Look for and manage any obvious causes, including a lifestyle check!
- Revamp your skin care:
o Switch to a gentle soap-free cleanser
o Avoid excessive exfoliation – NO physical scrubs, stick to gentle hydroxyacids or salicylic acid
o Check the pH of your products – the lower end of 4-5.5 is ideal
o Moisturising is key! Avoid irritants like fragrance or alcohol and include active ingredients that boost hydration and are proven to help repair the skin barrier like:
- Niacinamide - AKA Vitamin B3, it’s a real powerhouse for repairing the skin barrier in a number of ways including decreasing moisture loss, acting as an antioxidant and repairing cell DNA.
- Ceramides - These are the most important of the three types of lipids in the SC for maintaining the skin barrier function. The emerging evidence suggests that smaller ceramides can improve the skin barrier function.
- Hyaluronic acid - Hyaluronic acid (HA) is a key component in the structure of the outer layer of the skin and is essential for wound healing as well as skin elasticity. It is also extremely important for hydration, being able to bind water molecules over 1000 times its own weight.
- Panthenol - Dexpanthenol (the active form of panthenol or provitamin B5) acts as both a moisturizer and skin barrier enhancer. Studies of this ingredient aren’t as extensive as for some other ingredients but is recommended by many dermatologists.
o Protect
- Daily sunscreen is a must, preferably zinc oxide which doesn’t irritate.
There you have it, your skin barrier demystified. Focus your skin care efforts on doing all you can to keep it healthy, and the results will speak from themselves!