Natural Moisturizing Factor (NMF), Explained

Natural Moisturizing Factor (NMF) in Skincare

We’re starting to see the term natural moisturizing factors more and more as they’re the hot new ingredients formulated into several skincare products these days. They’re touted to be ‘good for the skin’ because apparently, our skin already has them. But that doesn’t really tell us anything, does it? To clear the air, here’s everything you need to know about natural moisturizing factors in skincare starting with the name. During my research, I’ve seen authors and researchers using the natural moisturizing factor (singular) in the literature whereas it’s commonly used in the plural in the less academic circle. Let’s get on the high horse, put on our smart glasses, align ourselves with the former and stick with the singular version, shall we?

Keep reading to learn what natural moisturizing factor is, its composition, and how it works in skincare.

What is Natural Moisturizing Factor?

The natural moisturizing factor (NMF) is a mixture of low molecular weight, water-soluble compounds present in the outer layer of the skin, which is called the stratum corneum (1).

Each of these individual compounds works as a humectant to attract and bind water to the skin. Therefore, the natural moisturizing factor plays an important role in the skin’s hydration by increasing water retention and preventing water loss.

What Are the Components of the Natural Moisturizing Factor?

Below are the components of the natural moisturizing factor and their approximate percentages present in the skin (2):

  • Amino acids such as serine, glutamic acid, and arginine | 40%
  • Pyrrolidine carboxylic acid sodium salt, also known as sodium PCA | 12%
  • Lactic acid | 12%
  • Urea | 7%
  • Minerals | 18%
  • And sugars, organic acids, citrates, and peptides

As you can see, NMF primarily consists of amino acids, which make up almost half of the NMF. These ingredients work synergistically to ensure healthy, hydrated skin.

How About Hyaluronic Acid?

Contrary to popular belief, hyaluronic acid is not a natural moisturizing factor. Even though it’s present in the skin and works as a humectant, it belongs to the family of glycosaminoglycans (GAGs) and not NMFs.

How is Natural Moisturizing Factor Formed?

You might be wondering how these ingredients come together or where exactly they come from. The natural moisturizing factor is formed when a certain protein called filaggrin breaks down (3).

So basically, your skin recycles this protein and converts it to natural moisturizing factors such as amino acids. Nothing goes to waste! In fact, filaggrin deficiency results in an increase in skin dryness and exposure to external irritants.

What’s The Importance of The Natural Moisturizing Factor?

The importance of the natural moisturizing factor lies in the fact that it is responsible for your skin’s hydration. And hydration is an important part of what makes a healthy skin barrier.

But that’s not all. NMF is not an isolated entity in the stratum corneum. It works together with the surrounding lipid layer, which consists of compounds like ceramides, to ensure the proper function of the stratum corneum.

When it’s not functioning properly, you experience an increase in what’s called transepidermal water loss or TEWL, which is characterized by dryness, flaky, brittle, and rigid skin.

In the grand scheme of things, NMF contributes to having well-hydrated, soft, and supple skin. Besides, a decline in NMF content in the skin is directly related to dry skin symptoms. In fact, the extraction of NMF compounds results in a 25% decrease in water content in the stratum corneum and a 66% loss of skin elasticity (4).

What Causes a Decrease in Natural Moisturizing Factor?

Besides the changes that happen to the skin due to the natural aging process (5), there are external factors that contribute to the loss/decline of natural moisturizing factors in the skin.

The most common of them is prolonged exposure to water as in bathing. NMF consists of humectants, which are compounds that are water-soluble. So contact with water actually causes leaching of these components from the skin.

Similarly, common irritants found in skincare products such as SLS also cause a reduction in NMF. And lastly, another factor we probably all know is low humidity, the ideal level being between 80% and 95%.

How Does Natural Moisturizing Factor Work in Skincare Products?

The idea behind using natural moisturizing factors in skincare products is to mimic your skin’s own composition. Several components of the NMF, such as amino acids, peptides, and minerals, are formulated into daily skincare products like moisturizers, serums, and toners.

So these products replenish the skin with compounds it already has and produces. But this isn’t something new. Because we already use several other compounds our skin naturally produces as ingredients in our products. Examples include hyaluronic acid, squalane, ceramides, and even vitamins. So the idea is the same.

But do they work? Do products with natural moisturizing factor/factors work? Yes. Urea, being one of the most abundant compounds in the NMF has been used to relieve dry skin since the 1940s (6). Similarly, lactic acid, though more popular for its gentle exfoliation benefits, is a great humectant that hydrates the skin.

How Can You Improve the NMF Content in the Skin?

To improve and maintain a proper level of NMF content in the skin, there are things you should do and things you should avoid.

1. Avoid long showers/baths.

As I’ve mentioned, long exposure to water is actually one of the most prominent causes of reduced NMF levels. For that reason, avoid taking long baths and soaking in water. Soaking, even though temporarily increases the water content at first, ultimately causes a significant reduction of the NMF components. Remember, water attracts water but water also retracts water.

2. Moisturize right after cleansing.

There’s no such thing as avoiding water. But there’s a reason why dermatologists recommend moisturizing right after cleansing or showering. While your skin is damp, a moisturizer provides a thin occlusive layer on the skin and prevents water from evaporating. That’s how you make sure that water doesn’t dehydrate your skin. The same logic applies to moisturizing quickly after applying a hyaluronic acid serum too. The aim is to prevent the water from latching onto a similar substance and evaporating from the skin.

3. Use topical natural moisturizing factors.

There are hydrating skincare products, especially moisturizers, formulated with natural moisturizing factors. The most popular one is The Ordinary’s Natural Moisturizing Factor + HA. While some products are easy to spot like that, some require a little bit more digging. For example, skincare products made with amino acids, though not always marketed as NMF moisturizers, are just as efficient in improving the NMF content in the skin. Because remember, NMF is largely made of amino acids. So look for several amino acids like glutamic acid, arginine, and histidine in your products to replenish your skin.

4. Choose the right skincare.

Remember, NMF is only half the story. In your own skin, the NMF compounds are enveloped by a lipid layer. So if you’re experiencing dry, dehydrated, or flaky skin, don’t just focus on NMF but also focus on improving the overall health of your skin barrier. Make use of ceramides and squalane in your skincare. This way, you both hydrate your skin and prevent further dehydration. Invest in a good moisturizer and apply it day and night.

5. Avoid irritants.

If you have sensitive skin, you’re probably actively avoiding common irritants in skincare products. But in case you’ve never paid attention to it before, know that irritants like sodium lauryl sulfate and certain alcohols have a drying effect on the skin. Even if you don’t notice anything right now or you don’t mind, the damage is there. And as we age, our skin’s ability to bounce back from these irritations declines too. So avoid these types of ingredients in your products, which are commonly formulated into face cleansers.

The Takeaway

So this is what the natural moisturizing factor is, how it works in your skin, and ways to use these compounds in your products. I’d like to get off my high horse here and invite you to make a few assumptions based on the words of Dr. Albert M. Kligman, the co-inventor of Retin-A:

No one dies of old skin! No matter how decrepit the integument becomes after a lifetime of assaults, it continues to perform its primary protective role.

Dr. Albert M. Kligman, 1979

In the light of this and just basic common sense, you do not need to worry about your skin ‘running out of natural moisturizing factors’. There is no such thing. Because our skin learns to adjust to the changes and ultimately adapts. Think about it. We go for a vacation in a cold climate and struggle with dry skin for the first few days. A few days or weeks later, it adapts! On the flip side, using our common sense again, we can say that our skin’s ability to adapt, just like its ability to do other things, simply weakens as we age. So don’t buy into the marketing claims; your skin doesn’t have to have that NMF-infused moisturizer to stay hydrated. It just makes things easier, that’s it!

References:

  1. Gunnarsson, M., Mojumdar, E. H., Topgaard, D., & Sparr, E. (2021). Extraction of natural moisturizing factor from the stratum corneum and its implication on skin molecular mobility. Journal of colloid and interface science604, 480–491. https://doi.org/10.1016/j.jcis.2021.07.012
  2. Draelos, Z. D. (2015). Chapter 17: Hand and foot moisturizers: Natural moisturizing factors [E-book]. In Cosmetic Dermatology: Products and Procedures (2nd ed., pp. 131–132). Wiley-Blackwell. https://doi.org/10.1002/9781119676881.ch19
  3. Robinson, M., Visscher, M., Laruffa, A., & Wickett, R. (2010). Natural moisturizing factors (NMF) in the stratum corneum (SC). I. Effects of lipid extraction and soaking. Journal of cosmetic science61(1), 13–22.
  4. Baran, R., & Maibach, H., I. (2017). Skin care products for normal, dry, and greasy skin: Care for dry skin [E-book]. In Textbook of Cosmetic Dermatology (Series in Cosmetic and Laser Therapy) (5th ed., pp. 170–171). CRC Press. https://doi.org/10.1201/9781315160504
  5. Farage, M. A., Miller, K. W., & Maibach, H., I. (2016). The stratum corneum and aging. In Textbook of Aging Skin (p. 55). Springer. https://doi.org/10.1007/978-3-540-89656-2
  6. Harding, C.R., & Rawlings, A.V. (2005). Effects of Natural Moisturizing Factor and Lactic Acid Isomers on Skin Function.
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