What Is Urea?
Urea is a naturally occurring hydrating ingredient naturally found within the skin. Urea is generally synthetically produced for use in skincare products such as lotions, creams, and anti-aging treatments.
Urea is a by-product of your body’s waste processing, more specifically it is a by-product of protein metabolism in the liver. Similar to hyaluronic acid, urea is a humectant. Humectants are ingredients that pull water into the skin allowing the skin to maintain water levels, necessary for skin health.
Urea is a naturally occurring substance found in the surface layer of our skin. It is an active part of our natural moisturizing factor or NMF. NMF is a group of molecules that regulate the level of moisture on our skin surface by binding water molecules in order to protect from severe drying. NMF includes sodium PCA, free amino acids, salts sugars, lactic acid, and, of course, urea. Urea makes up about 7% of NMF.
Healthy skin has approximately 28 micrograms of urea per square centimeter. Low levels of urea have been linked to a decreased water-binding capacity within the skin, which in turn leads to roughness, tightness, flaking, and irritation.
In fact, those that suffer from skin conditions such as psoriasis or eczema could have up to 80% less than someone with normal skin. NMF also decreases as we age.
Urea
the good:Urea naturally occurs in the skin and helps to maintain water levels, improve skin health and protect the skin against, damage, infection, and water loss.
the not so good:Nothing to keep an eye on here.
Who is it for?All skin types except those that have an identified allergy to it.
Synergetic ingredients:Works well with most ingredients.
Keep an eye on:Urea can increase the absorption of other ingredients, so it is best to use a safely formulated product.
What Are The Benefits Of Urea?
When used topically, urea is known for its five main benefits. These benefits include: retaining moisture, barrier maintenance, exfoliation, increasing permeability, and providing pain and itch relief.
Moisture
Urea functions as a humectant-type moisturizer in order to help the skin better retain moisture.
A humectant is a hygroscopic substance. Hygroscopic means that it is water-loving or water-absorbing. The molecular structure of the urea molecule allows it to bind to water readily.
When urea is present in the skin, either as part of normal skin function or when topically applied it retains water and absorbs it from the air.
This water-loving molecule may help to reduce transepidermal water loss. Transepidermal water loss or TEWL refers to water that is lost to the air through evaporation. TEWL often occurs when the skin’s barrier is damaged, as we age or in dry climates. This function of urea makes it a very useful ingredient for those with dehydrated skin.
Skin’s Natural Barrier
The next function of urea is barrier maintenance. The skin’s natural barrier is comprised of corneocytes, ceramides, cholesterol, and free fatty acids. A strong, intact barrier is important to keep moisture in and keep things like allergens, bacteria, and irritants out.
When the barrier is weakened, these intruders can pass through the top layer of skin, causing damage that has been linked to common skin conditions such as acne, rashes, sensitive skin, and even signs of aging.
A 2012 study published in the Journal of Investigative Dermatology found that topical applications of 20% urea may improve skin barrier function and improve the skin’s defense against bacteria and microbes.
Exfoliation
Another beneficial function of urea is exfoliation. Urea exfoliates the skin by dissolving the intercellular matrix of the corneocytes that make up the stratum corneum. Basically, urea dissolves the glue that holds some dead skin cells together.
The mild exfoliation that urea provides the skin may help to improve the water content and barrier function of the skin. This is because dead skin cells actually play an important role in protecting the skin and form the basis of the skin’s natural barrier. However, when you have dry, flaky, or peeling skin, it can be hard for the skin barrier to function properly. This is where a little gentle exfoliation is sometimes healthy.
However, exfoliation should always come with a little warning as over exfoliation can also reduce the effectiveness of the skin barrier and reduce the hydration of the skin.
Absorption
Urea functions as an ‘absorption enhancer’, which means that it improves the permeability of the skin.
The enhancer effect of urea is attributed to an increase in the skin’s moisture levels. This function of urea can be beneficial when the goal is to help other active ingredients penetrate the skin better.
However, this function of urea can be detrimental if urea is formulated with ingredients that can cause sensitization.
Pain Relief
Finally, urea may have a mild pain relief effect on the skin. Urea may provide local pain and itch relief when applied topically.
This is especially helpful if you have a skin condition; it can break the cycle of flare-ups and uncomfortable inflammation.
However, keep in mind that this benefit has mostly been explored in studies that use urea in conjunction with other complementary ingredients that may increase this ability.
Is Urea Vegan?
Urea can be derived from animal urine and can be synthetically produced. While sources can include animal byproducts, it is generally made synthetically. However, it is always best to check with the brand that you are considering purchasing.
Is Urea Safe?
The safety of urea has been assessed by the Cosmetic Ingredient Review Expert Panel. The CIR Expert Panel is a group that is responsible for the independent evaluation of skincare and cosmetic ingredients for safety and efficacy.
The Expert Panel evaluated the scientific data and concluded that urea was safe as used in cosmetics and personal care products.
The Expert Panel did note that urea can increase the absorption of other ingredients and that this should be taken into account when conducting product safety assessments.
References:
Grether-Beck S, Felsner I, Brenden H, et al. Urea uptake enhances barrier function and antimicrobial defense in humans by regulating epidermal gene expression. J Invest Dermatol. 2012;132(6):1561-1572.
Loeffel ED. Topical urea. Calif Med. 1972;116(6):48-49.
