What is skin barrier
Skin barrier is the outer most layer of skin called the outer stratum corneum. It is the dead tissue that helps protecting inner cells from the environment. Skin barrier has strong mechanical shear that can resist impact, prevents water evaporation, protects invasion of foreign bodies, regulates body temperature. This outer most layer is the habitat of many natural microbes. Skin barrier is composed of 15–20 layers of flattened dead cells with neither nuclei nor cell organelles. High amount of filamentous keratin is observed in these dead cells. These corneocytes are glued together into sheet 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 lost and environmental impact.
Amount and type of lipids in the skin barrier affect directly the strength and permeability of this layer . Types and ratioes of lipids in skin barrier differs in respective to location on the body. In addition, amounts and ratioes 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 is essential and skin barrier is a result from 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 assembly into the great barrier.
Skin barrier is a habitat of various microbes. These natural micro organism live togehter on skin under a balanced condition, called microbiome. These microbes play roles 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 proliferation of pathogenic bacteria. There are also relationships between the development of our immunity and microbiomes. Microbiome in skin barrier layer is essential for healthy skin.
How to make your skin barrier healthy
Experiment in pigs revealed that 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. Rate of water evaporation from these pigs was 5 times those of normal diet. Analysis of skin barrier from pigs deprived of essential lipids for ceramide synthesis indicated abnormal ceramide structures.1
Therefore, healthy diets is essential for 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 routines are not really healthy for your skin barrier. Examples include face masking with fruits with too acidic pH, scrubbing face with hush materials, washing face vigorously, using too strong cleansing product.
Products with too much preservatives can also harm your natural skin microbiomes.
Products with peeling agent 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 skin to form strong skin barrier.
Wash your face correctly
Surfactants in cleanser works by capturing lipids on your skin and bringing them into water. Once these lipids together with dirts are washed away, you feel clean. Nevertheless, surfactants cannot differentiate among secreted lipids on the face, dirts and lipids that are part of skin barrier. As a result, many cleansers can wash away natural lipids in the skin barrier, resulting in weakening or ripping our natural skin barrier.
Face washing should clean only dirt and secreted lipids on skin surface without washing out lipids in the skin barrier. When skin barrier is disrupted, one can feel the tightness and dryness of the skin.
To minimally disturb skin barrier, face washing should be carried out with the following cautions:
- Always wet your face with lot of water first
- Do not put undiluted cleansing gel or foam directly on facial skin
- Use only 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 generaoulsly
- No strong rubbing or scrubbing
- When your face is quite dirty, two time washing is better than one time washing with concentrate surfactants. The first round can be done very quickly. The final rinsing should be done genorousely
- Avoid strong cleanser that leaves your skin feeling dry.
- Do not use hot water, use regular water.
How to remove makeup
If you put on foundation or water resistant makeups, remove them with oil-base makeup remover before using water-based cleanser. Water-based cleasers that can clean water resistant makeup by regular face washing usually contain strong surfactants. Sensistive 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.