Urea is a humectant, referred to as hydroxyethyl urea, not to be confused with the preservatives imidazolidinyl urea and Diazolidinyl Urea.
It is a naturally occurring substance found on the surface of the skin. It is an active part of our natural moisturising factor (NMF), which functions to keep our skin lovely plump, supple, and working efficiently.
Urea is a natural component of skin’s tissues. It makes up 7% of our natural moisturising factor, along with 12% sodium PCA and 9% glycerol, all of which are water-binding – which is essential for maintaining the health, function, and hydration of the outer layer of skin.
Like many naturally occurring compounds in the skin, urea decreases with age and trauma from harsh ingredients and environmental pollutants, making the skin more susceptible to dryness, inflammation, and ageing.
Topically applied, those with dehydrated and dry skin can see an improvement in their symptoms of as much as 50%, and in those with eczema, as much as 80%.
There is also evidence to suggest, that urea helps to treat skin conditions such as ichthyosis, dermatitis, psoriasis, xerosis, and even nail fungus – all these conditions share a similar pathological cause — namely, a yeast called Malassezia.
Hydrophilic: This term means “water-loving”, which gives urea its amazing ability to hold onto water molecules, keeping your skin plump and moist.
Not only does it readily absorb water, but it also has a very high-water content, which helps to reduce the amount of water that is lost through your skin.
On a molecular level, urea modifies the structure of amino chains and polypeptides within your skin, which is important for moisturising the skin’s delicate tissues. There is a direct correlation between the skin’s water content and its levels of amino acids. Basically, the more dehydrated and dry the skin is, the lower its share of dissolved amino acids.
Studies suggest that urea’s keratolytic and hydrating effects are due to the breakage of hydrogen bonds in the stratum corneum, the outer layer of skin; it is essential to loosen epidermal keratin and increases the water-binding sites within the skin.
Improved barrier function: One of the many ways urea benefits skin is strengthening and protecting the barrier function and keeping it healthy.
Natural Exfoliant: At higher percentages within a formula urea becomes a natural keratolytic (exfoliator). This, combined with its hydrating properties, makes it a potent skin treatment. Urea works in synergy with other ingredients like lactic acid, which make up the molecular structure of healthy skin, thus enhancing the penetration of other ingredients.
Combined, urea and lactic actively remove dead skin cells and substances from the skin; improving cellular turnover, whilst dramatically improving the water-binding capability of the skin, literally rebuilding skin from the inside out.
Possible Anesthetic: Urea has another interesting profile; it can create a local anaesthetic effect on your skin and has anti-itch properties. This is really useful in reducing cycles of inflammation and flare-ups, making it our ingredient of choice if you have sensitive skin.
Penetration: Studies have found that urea plays a key role in increasing the permeability of certain skin care ingredients, working as a vehicle for other performance ingredients, by encouraging them to penetrate the epidermis easily.
Natural Moisturiser: Dry skin can be due to a reduction of urea in the skin’s tissues, leading to tightness and flakiness. Urea is a key component of the natural moisturising factor found within your skin, offering instant relief if you have dry skin.
The sciencey skin bit
To understand how urea works, it is important to understand skin’s structure:
The outermost layer of skin the stratum corneum – is made up of corneocytes and an intercellular cement which has a high resistance to many chemical agents. Inside the corneocytes is a natural moisturising factor (NMF), here a mixture of substances regulates moisture levels on the surface by binding water molecules.
Whilst applications of emollients and occlusive ingredients coat skin’s surface to create instant moisturisation it is only a temporary fix; they don’t improve skin’s ability to create and hold water the way urea does. When applied to the skin, it penetrates the stratum corneum where it readily absorbs and retains water; increasing skin’s capacity to hold moisture and rehydrate.
To conclude, it helps to regulate the cell cycle; encouraging natural desquamation or exfoliation, enhancing your barrier function, which in turn regulates the good micro-flora that keeps your all-important acid mantle intact.
The dry skin connection
Dry skin results from a lack of oil and water in the outer layer of your skin; thus, your skin can become scaly, cracked, and itchy.
Moisture is normally retained in the epidermis by a surface film of substances, urea is one of these water-holding substances, along with lactic and amino acid.
As discussed previously, reduced levels of urea can lead to a lower water-binding capacity within the skin, which in turn leads to roughness, tightness, flaking, and irritation.
Research has found a link between severe dry skin conditions and drastically reduced urea in the stratum corneum. Urea stimulates the skin components that keep it healthy, which is referred to as epidermal gene expression.
When applied topically, it increases filaggrin formation; an important protein found within the skin keeps everything balanced. It also maintains a healthy barrier function by building up skin’s defence mechanisms.
Less than 10%: This can help with water retention in your skin, helping to bind moisture; this is due to its extremely hydrophilic nature, making it a popular choice for its moisturising
- skin naturally produces urea
- it regulates skin’s moisture content and is an essential component of natural moisturising factor (NMF).
- urea is hygroscopic – it is able to bind moisture on to the outermost layer of the skin.
- it is the perfect treatment for dry skin, it has anti-itch and anti-microbial properties.
- it can help to prevent acne-causing bacteria.
- it is a keratolytic at higher percentages, meaning it breaks down the connections between dead skin cells; naturally exfoliating skin and helping ingredients to penetrate further.