Skin barrier – four things you should know

Our skin is unique! Did you know that the skin is the largest organ in the human body? The skin is extremely thin but has the power to protect the whole organism thanks to the skin barrier. The skin barrier protect from environmental factors, injuries, harsh substances, allergens as well as prevent from microbial invasion. It’s the first line of defence.

The skin protects from excess water evaporation – transepidermal water loss (TEWL). This is a natural process which allows to loose approximately 500 ml of water every day form the skin. Water is crucial for all processes taking place in the skin, therefore any excess of TEWL can lead to skin dehydration and disruption in skin’s function and flexibility. The good news is that our skin creates a protective coat – skin barrier.

Below I will explain the four things you should know about your skin barrier structure and the role it plays. This will help you understand why it’s important to hydrate the skin and restore the skin barrier in your everyday skincare.

 

Skin barrier structure – stratum corneum and skin lipids

Stratum corneum is the outermost layer of the epidermis which looks like a brick wall. Imagine  lots of bricks connected to each other with mortar to make a strong wall.  Bricks are our skin cells  connected with intercellular binder (skin lipids).

Skin cells are produced in the bottom layer of the epidermis called basal layer.  They are living cells which grow and move up through epidermis until they reach stratum corneum. Then they die and eventually shed from the skin surface. The whole process is called keratinisation or skin renewal. During the skin renewal process there is also a production of skin lipids and components of Natural Moisturising Factor (NMF).

Skin lipids which surround skin cells create an almost waterproof coat protecting from water evaporation. Skin barrier lipids are mainly ceramides (60%), cholesterol (20%) and essential fatty acids (20%) such as omega-6 linoleic acid (LA), omega-3 α-linolenic acid (ALA) and omega-6 γ-linolenic acid (GMA).

NMF is a combination of different substances – humectants which have the ability to retain water. It includes amino acids, urea, lactic acid and glycosaminoglycans.

Stratum corneum  with skin lipids and components of NMF provide a healthy complexion. Damaged skin structure with holes in the skin’s brick wall makes water easily evaporate. As a result leading to skin dehydration, irritatation and inappropriate regeneration.

 

 

Sebum secretion

Sebum is an oil secreted by sebaceous glands. They occur almost all over the body with higher concentration on the face, chest and back. Skin oil creates an occlusive coat on the skin surface and protects from water evaporation. It also has antibacterial and antioxidant properties. There are few things which have a huge impact on sebum secretion. There are hormones, diet, stress level as well as skincare.

If the skin loses too much water and becomes dehydrated sebum secretion can increase, leading to oiliness and formation of clogged pores. Therefore, if your skin type is ‘combination’ or ‘oily’ you shouldn’t use too strong, degreasing ingredients. They can damage the skin barrier and only aggravate the problem with oiliness and cause breakouts or even acne.

 

Acid mantle

 

Skin microbiome as a protective skin barrier agains infections 

You may think that bacteria, viruses and fungi are the only harmful microbes which lead to infection. The truth is that most of microbes live in close association with humans and are very beneficial to us. Human microbiome in and on the body produces antimicrobials  providing protection against foreign harmful invaders. It also contributes to the immune response stimulation, production of vitamins as well as helps with digestion.

Our skin is has a unique microbial community i.e. Malassezia spp., Priopionibacterium acnes, Staphylococcus aureus. These microbes are commensals which means that in normal circumstances are non-pathogenic.  Microbial imbalances (microbial dysbiosis) can activate an immune response, changing commensals to pathogens. This can lead to inflammation and skin diseases like acne, atopic dermatitis, psoriasis, seborrheic dermatitis.

 

Despite being extremely thin, our skin has an extraordinary and unique defence mechanism which fights for a healthy, beautiful and flawless complexion. We can help it by protecting and reinforcing the skin barrier using an appropriate skincare, as well as avoiding  triggers which can cause imbalances.

Replenishing the skin barrier should be the first skincare goal for every skin type. Skin with disrupted protective barrier will never achieve your desired, long-term skincare effects. In the next article I will describe how to take care of skin with impaired skin barrier.

Stay tuned and be Skin Aware,

Paulina