Youthful skin with a visible glow – it’s the holy grail of skin care.
Well, what if I told you the key to super healthy skin is hydration? A dehydrated skin causes horizontal lines to appear, the types of lines that lead to deep-seated wrinkles, especially if not treated correctly – that’s right, something as simple as keeping your skin plump and moist can ward off premature ageing.
But, shhh! There is one little “beauty secret” that not too many people know. Urea – which, in my opinion, is one of the most effective moisturising ingredients in cosmetic chemistry.
Urea’s role within the skin is to maintain a healthy moisture balance; keeping it soft, supple, and youthful, bringing much-needed relief to dry skin.
SO, WHAT IS UREA?
Urea is a humectant; not to be confused with urea derivatives that act as preservatives – imidazolidinyl and diazolidinyl urea – which I discuss in more detail below.
Urea is a naturally-occurring substance found in the surface layer of our skin, and is an active part of our natural moisturising factor (NMF), which functions to keep skin hydrated, protected, and working efficiently. It is made up of 40% amino acids, 12% sodium PCA, 9% glycerol, and 8.5% urea – all of which are water binding (hygroscopic) componenets of the skin that are essential for maintaining the health, function, and hydration of the stratum corneum.
A healthy skin will typically contain 28 micrograms of urea per square centimeter. A dehydrated, dry skin can see a reduction of as much as 50%, and in those with eczema as much as 80%. There is evidence to suggest that urea helps treat ichthyosis, dermatitis, psoriasis, xerosis, and even nail fungus.
THE SCIENCY SKIN BIT
In order to understand how urea works, it is important to understand the skin’s structure. Your outer layer of skin – the stratum corneum – is made up of corneocytes, an inter-cellular cement which has a high resistance to many chemical agents.
Inside the corneocytes is a natural moisturising factor (NMF), a mixture of substances that regulate the level of moisture on our skin surface, by binding water molecules.
As discussed above, urea is a natural component of our skin’s tissues and makes up 7% of our natural moisturising factor, which decreases with age. Whilst applications of emollient and occlusive ingredients coat the skin’s surface, creating instant moisturisation, it is only a temporary fix. It won’t improve the skin’s ability to create and hold water the way urea does.
When it is applied to the skin, it penetrates the stratum corneum, where it readily absorbs and retains water; thus increasing the capacity of the skin to hold moisture and rehydrate.
To conclude, it helps to regulate the cell cycle, encouraging natural desquamation or exfoliation, enhancing your barrier function, whilst regulating the good micro-flora that resides on your skin to keep your protective acid mantle intact.
“Urea appears to be a highly-active small molecule regulator of genes that impact keratinocyte differentiation, lipid synthesis and antimicrobial peptide production, together leading to improved permeability barrier function and likely antimicrobial defense as well.” (1)
DRY SKIN CONNECTION
Dry skin is a result of lack of oil and water in the outer layer of skin the epidermis. Skin becomes scaly, cracked and itchy.
Moisture is normally retained in the stratum corneum by a surface film of oils (sebum), broken-down skin cells, and natural water-holding substances. Urea is one of the water-holding substances, the others are lactic and amino acids.
We know reduced levels of urea leads to a lower water-binding capacity within the skin, which in turn leads to roughness, tightness, flaking, and irritation.
Research has also found a link between severe dry skin conditions such as ichthyosis, psoriasis, and eczema; they could be a result of drastically reduced amounts of urea in the stratum corneum.
UREA’S SKIN LOVING BENEFITS
This means that urea has an amazing ability to hold on to water molecules, keeping our skin moist. It also has anti-itch properties.
Not only does it readily absorb water, but it also has a very high water content, which helps to reduce the amount of water lost through the skin.
On a molecular level, urea modifies the structure of amino chains and polypeptides within the skin, which is important for helping to moisturise our delicate tissues.
Research has found a direct correlation between water content and the amino acid content of our skin – basically, the more dehydrated and dry the skin is, the lower its share of dissolved amino acids.
To learn more about the damaging effects of dehydrated skin, follow the link.
Improves Barrier Function
One of Urea’s many benefits is that it helps to accelerate the skin’s cellular renewal process.
The really great thing about this is that it strengthens the barrier function of the skin, helping to keep it youthful and healthy.
Urea has powerful keratolytic properties that, combined with its hydrating properties, make it a potent moisturising and exfoliating treatment for the skin. It helps other ingredients penetrate deeper, whilst working in synergy with ingredients that create the molecular structure of healthy skin, such as lactic acid.
Combined, these two ingredients actively work to remove dead skin cells and substances from the horny layer, improving cellular turnover in the epidermis, helping to dramatically improve the water binding ability of the skin, literally REBUILDING HEALTHY SKIN from the inside out.
Urea has another interesting profile; it can create a local anesthetic effect on the skin.
Studies have found, one of urea’s key roles is to increase the skin permeability of certain skin care ingredients, working as a vehicle for other performance ingredients by encouraging them to penetrate the epidermis easily.
Often, a dry skin is due to a reduction of urea in the skin’s delicate tissues, which can lead to tightness and flakiness; because of urea’s natural moisturising factor, it can offer instant relief to dry skin.
I include Urea in H2O Hydrating Complex; once on the skin, it helps to hydrate and repair the skin cells.
The gentle exfoliating action of urea helps to leave the skin super smooth, especially when layered. The texture of the skin visibly feels so much softer, giving it a youthful glow. I have seen some great results from urea on my clients who suffer from extremely dry, dehydrated skin.
UREA’S BEST BITS
Phew, with so many beautifying properties, where do you begin?
For the benefit of those who require a little recap, here are this cool little ingredient’s best bits:
- Urea is naturally produced by our skin
- It regulates our skin’s moisture content and is an essential component of our Natural Moisturising Factor (NMF); regulating skin’s moisture content
- Urea is hygroscopic, which means it is able to bind moisture on to the outermost layer of our skin
- The perfect treatment for dry skin, it has anti-itch and anti-microbial properties
- It is also keratolytic, meaning it breaks down the connections between dead skin cells, naturally exfoliating the skin and helping ingredients penetrate further
THE NAKED TRUTH
Urea is often referred to as Carbamide, the primary organic solid of urine; this is waste that has been produced by the body after it metabolises protein.
Thankfully, the urea used in the cosmetic industry that I use is from synthetic sources and not animal-derived; it is formed from ammonia and carbon dioxide, and can be produced in either a solid or liquid form.
The other two forms of urea found in personal care products are imidazolidinyl and diazolidinyl urea, both of which are antimicrobial preservatives used to protect personal care products from bacteria, yeast, and mold. They do get a lot of bad press as a preservative, due to the fact that they are proven formaldehyde releasers.
I do hope I have gone some way to answer your questions on what is urea, I appreciate that a dry skin is a really frustrating skin type to treat, simply because it causes so many conditions within the skin:
- Dehydration due to a lack of water
- A lack of a protein called Fillagrin
- Dryness because of a reduction in ceramides and moisturising lipids
If dryness is an issue for you, I have put together a complete section on dry skin that you may find useful.