What is skin barrier
The skin barrier is the outermost layer of skin, called the outer stratum corneum. It is the dead tissue that helps protect inner cells from the environment. The skin barrier has strong mechanical shear that can resist impact, prevent water evaporation, protect against invasion of foreign bodies and regulate body temperature. This outermost layer is the habitat of many natural microbes. The skin barrier is composed of 15–20 layers of flattened dead cells with neither nuclei nor cell organelles. A high amount of filamentous keratin is observed in these dead cells. These corneocytes are glued together into sheets with a lipid matrix composed of ceramides (50%), cholesterol (27%), and fatty acids (10%). On top of this top stratum corneum layer is the thin layer of sebum recreated from the underneath sebaceous glands. The oil-coated skin barrier is a great water-resistant material that protects the body from water loss and environmental impact.
The amount and type of lipids in the skin barrier affect the strength and permeability of this layer . Different parts of the body have different types and amounts of lipids in the skin barrier. In addition, the amounts and ratios of lipid types in the skin barrier change with age and season.
Before living things could move out of water into dry land, evolution in protecting water loss was essential, and the skin barrier is a result of a long evolution. It is the cleaver assembly of lipids and dead cells. The dead cells are also well-prepared, i.e., a lot of filamentous proteins and fats are accumulated inside these cells prior to their death. Lipids and such dead cells assemble into the great barrier.
The skin barrier is a habitat for various microbes. These natural microorganisms live together on skin under a balanced condition called the microbiome. These microbes play a role in protecting the host from being invaded by pathogenic microbes. There are complex relationships between these microbes and lipids in skin barriers; e.g., digestion of some lipids by some microbes results in essential lipids that can inhibit the proliferation of pathogenic bacteria. There are also relationships between the development of our immunity and our microbiomes. Microbiomes in the skin barrier layer are essential for healthy skin.
How to make your skin barrier healthy
An experiment in pigs revealed that a 2-month diet deprived of lipids required in ceramide biosynthesis (the experiment used coconut oil in place of regular vegetable oils containing linoleic acid) resulted in cracked, dry skin. The rate of water evaporation from these pigs was five times that of their normal diet. Analysis of the skin barrier from pigs deprived of essential lipids for ceramide synthesis indicated abnormal ceramide structures. 1
Therefore, healthy diets are essential for a healthy skin barrier. Oil with unsaturated fatty acids such as linoleic acid is essential for biosynthesis of ceramics by our body. Most vegetable oils, except coconut oil, contain this essential fatty acid. Several nuts also contain this fatty acid.
- Melton JL, Wertz PW, Swartzendruber DC, Downing DT, Effects of essential fatty acid deficiency on epidermal O-acylsphingolipids and transepidermal water loss in young pigs. Biochimica et Biophysica Acta 921 (1987) 191-197.
Many skin care routines are not really healthy for your skin barrier. Examples include face masking with fruits with too acidic pH, scrubbing the face with harsh materials, washing the face vigorously, using too strong cleansing products.
Products with too many preservatives can also harm your natural skin microbiome.
Products with peeling agents such as salycylic acid or glycolic acid can make your skin barrier weak and imbalanced. These peeling agents inhibit the connection of cells, resulting in an inability of the skin to form a strong skin barrier.
Wash your face correctly
Surfactants in cleansers work by capturing lipids on your skin and bringing them into water. Once these lipids, together with dirt, are washed away, you feel clean. Nevertheless, surfactants cannot differentiate among secreted lipids on the face, dirt, and lipids that are part of the skin barrier. As a result, many cleansers can wash away natural lipids in the skin barrier, resulting in the weakening or ripping of the natural skin barrier.
Face washing should clean only dirt and secreted lipids on the skin surface without washing out lipids in the skin barrier. When the skin barrier is disrupted, one can feel the tightness and dryness of the skin.
To minimally disturb the skin barrier, face washing should be carried out with the following caution:
- Always wet your face with a lot of water first
- Do not put undiluted cleansing gel or foam directly on facial skin
- Use only a small amount of cleanser and dilute it with water on your hand first
- Lathering of surfactants on facial skin should be done quickly
- Rinsing out surfactants with water should be done generously
- No strong rubbing or scrubbing
- When your face is quite dirty, twice-washing is better than once-washing. Each round should be done quickly. The final rinsing should be done generously.
- Avoid strong cleansers that leave your skin feeling dry
- Do not use hot water; use regular water
How to remove makeup
If you put on foundation or water-resistant makeup, remove them with an oil-base makeup remover before using a water-based cleanser. Water-based cleansers that can clean water-resistant makeup by regular face washing usually contain strong surfactants. Sensitive skin and acne-prone skin should avoid these cleansers. Wiping makeup gently with mineral oil or coconut oil or makeup remover prior to regular face washing will allow you to use your normal cleanser that does not disrupt your precious skin barrier.