Hydration, hydration, hydration!
This is what valuable humectants bring to your skin, they are the antidote for dehydrated and dry skin conditions.
All Skin Types Require Water
Any skin can require hydration – even oily skin – if we remember dry skin lacks oil, and dehydrated skin lacks water.
This is a subject I discuss in the article, “The Clear Skin Difference: It Begins With Hydration.”
Therefore, our skin requires a mixture of both oil-rich and water-rich ingredients to be healthy.
- Some natural botanical oils found in skincare products, such as jojoba or squalane, mimic the skin’s natural oil, sebum.
- Humectant ingredients are water-rich; they mimic the skin’s sweat and work by hydrating the skin. They have been specifically designed to prevent water loss and protect the stratum corneum, the outer layer of the epidermis, from becoming dry and parched.
The Role of Humectants
Without getting too technical, the key functionality of a humectant is to form hydrogen bonds with molecules of water, this is why humectants are considered an important ingredient for dry and dehydrated skin.
The reason we like to add humectants to our formulae is due to their ability to attract water like a magnet; physically binding water to them. Some humectants are capable of holding up to 1000 times their own weight in water.
Why Is Skin Hydration So Important?
Water is absolutely essential to the normal functioning of the skin. The skin’s intercellular communication system regulates the amount of water it loses via trans-epidermal water loss; a function that can only work correctly if the skin’s barrier function isn’t damaged. Skin with an impaired moisture barrier has an increased rate of trans-epidermal water loss, which can result in rough, dry, and flaky skin, which becomes prone to inflammation, irritation, premature ageing, and skin conditions like eczema.
Skin that is not adequately hydrated is also not able to perform important functions correctly – such as desquamation, the skin’s natural exfoliation process, and the formation of the cornified cells, which creates the protective barrier; our skin’s first line of defence against environmental insults.
This is not the only thing that increases trans-epidermal water loss; changes in humidity, using high pH cleansers, and astringent products may also result in more water loss from the skin.
Does The Skin Naturally Contain Humectants?
Yes, it does contain natural humectants which are collectively referred to as the skin’s natural moisturising factor – or the NMF, for short. Their job is to form a protective coat that keeps the outer layer of skin adequately hydrated. This natural skin moisturiser is primarily made up of hyaluronic acid, lactic acid, sodium, urea, various sugars and amino acids; including pyroglutamic acid, which is the precursor of sodium PCA.
Interestingly, studies have found that not only does the NMF work to increase the water content in the stratum corneum the outer layer of skin, but specific components especially glycerol and urea, an important humectant that you can read all about here, work to retain the fluidity of proteins and lipids under dehydrating conditions. Thus ensuring that the skin will still carry out important functions, even in dehydrating conditions.
Because these ingredients deplete with age and can cause a number of conditions including sensitivity, inflammation, dehydration, dryness and inflamed breakouts, many of our skincare products are actually formulated to mimic the NMF by using a combination of humectants, emollients, and occlusives.
Without these natural humectants keeping our skin soft and supple, the barrier repair function would out of balance, making the skin less permeable to water and other beneficial ingredients. This is why humectants are valuable ingredients in skincare – not only do they help to hydrate the skin, but they repair and replenish, helping to ward off premature ageing, whilst helping other compounds ingredients to penetrate more effectively.
Humectants Decrease With Age
As we age, the level of humectants naturally present in the skin decrease, this is why you start to experience drier and more dehydrated skin as we age. Therefore, replenishing the NMF through the external application of skincare products containing humectants will help to keep skin, moist and plump and more youthful in appearance.
Types of Humectants Used in Skincare
- Hyaluronic Acid has potent hydrating capabilities. it can hold anywhere between 600 – 1000 times its own weight in water; perfect for parched, dehydrated skin.
- Glycerin also referred to as Glycerine and Glycerol. In fact, glycerin is found in natural fat or lipids, it is an extremely safe and non-allergenic skin care ingredient, and its got a long history of use. This is a powerful humectant that works really well as a hydrating agent. I personally like the fact that it keeps on working long after the product has been rinsed off the skin, you can read more about Glycerine here.
Urea is a little know but very important water-loving agents which you can read about here.
- Butylene Glycol is an ingredient you will often find in skincare products for dry skin, it is more popular than propylene glycol, which can be irritating to a sensitive skin due to its permeability.
- Sorbitol an ingredient that can be used to replace Glycerine, it is a great hydrating agent that has similar benefits as glycerine.
- Sodium PCAlLike Hyaluronic Acid, this ingredient works really well to hydrate by helping to attract water to the skin. Sodium PCA is often used alone or within an oily formula due to its lightweight properties, you can read more about Sodium PCA here.
- Seaweed and Algae are perfect for hydrating mask formulae, they work by creating a moist film over the surface of the skin, helping to retain water in the skin’s upper layers, these ingredients are extremely nourishing and moisturising.
Urea is an Important Humectant
When used at concentrations below 10% it is one of the most effective humectants. Comprising about 8 percent of the natural moisturising factor. In fact, a healthy, non-dehydrated skin will typically contain around 28 micrograms of Urea per square centimetre, so you can see why it is an important humectant.
Interestingly, xerotic skin conditions or abnormally dry skin is associated with a huge reduction in the concentration of urea in the skin, up to 30% less in the skin with those suffering from psoriasis and as much as 85% less in the skin with those suffering from eczema.
Interestingly it is as effective as Glycerin at keeping the skin moist and hydrated – and imparts a more favourable, less sticky skin feel. Unlike Hyaluronic acid, Urea is easily able to penetrate the skin.
Urea actually has three additional benefits for the skin:
- It encourages natural exfoliation of cells when used at concentrations that are higher than 10%, by breaking down intercellular bonds between dead skin cells, this is why it makes urea a perfect ingredient for treating keratosis pilaris and hard dry skin on the foot.
- Because it breaks down these bonds, it helps other skincare ingredients penetrate more effectively
- It helps to regulate microbes on the skin, thereby enhancing the acid mantle and rebuilding the skin barrier function).
- Studies are also finding that Urea may be effective in treating fungal acne, as it inhibits the yeast Malassezia.
And yes, urea is also a component of urine, however, there’s no need to be grossed out when it comes to the Urea used in skincare products because it is synthetically-derived.
The Naked Truth
Using humectants can be a double-edged sword.
Humectants are really good at attracting water molecules to the skin – but in saying that you have to consider where do the water molecules come from and how does this affect us? Humectants pull water molecules from their surrounding environment. In most cases, this is of course from the air, if the humidity is high enough – which is generally greater than 80%. However, if you live in a dry climate and there is not a lot of moisture in the air, then chances are that the humectants will actually pull water from the deeper layers of your skin, which can cause dehydration problems.
This interesting article is on trans-epidermal water loss, it shows that there is a general pattern of decreasing water loss with the rising humidity.
So does this mean we should be avoiding humectants if we live in a dry climate? Of course not you just need to apply your humectant product such as H20 or Quench and then apply your moisturiser to ensure you are locking all that skin hydrating, plumping goodness against your skin.