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NMF is a cocktail of ingredients that the skin naturally creates to keep the stratum corneum hydrated.
Firm + Replenish Serum is designed to replenish skin’s Natural Moisturizing Factor after cleansing and exfoliating. What is NMF and why is it so important? Here’s a primer on skin’s natural moisturizer.
Before we dive into the science of NMF, let’s take a closer look at human skin. The outermost layer of the epidermis is called the stratum corneum. Imagine the stratum corneum as a brick wall. The bricks are corneocytes, which are made of tiny keratin fibers in an organized matrix. The “mortar” is comprised of lipids like Cholesterol and Ceramides. This “brick wall” is your primary barrier between the skin and the world.
Inside the corneocytes, or “bricks,” skin produces Natural Moisturizing Factor (NMF). NMF is a cocktail of ingredients that the skin naturally creates to keep the stratum corneum hydrated. These include Amino Acids, Lactic Acid, Pyrrolidone Carboxylic Acid (PCA), and Hyaluronic Acid (HA). (See the bottom of this story to learn how each of these components helps the skin.)
Approximately 20 – 30% of the dry weight of the corneocyte is comprised of NMF. The components of NMF are humectants, which means they attract water like a magnet. NMF draws water in, allowing the stratum corneum to stay hydrated. When the stratum corneum is hydrated, skin appears healthy, replenished, and youthful.
Why should we apply NMF topically?

If skin creates NMF on its own, why do we need to apply NMF topically? NMF is easily compromised by environmental factors. The lipids (or the “mortar”) work to protect the corneocytes from NMF loss. Try as they might, NMF is easily stripped away by common cleansers and skincare products. Interestingly enough, as NMF components are water-soluble, prolonged contact with water also dissolves NMF, making skin feel even drier. Additionally, the level of NMF in our skin decreases as we age.
The skin does replenish NMF on its own, but it requires energy to do so. Our Firm + Replenish Serum features a potent dose of NMF so your skin doesn’t need to work so hard to replenish NMF on its own. Instead, your skin can use its energy to repair itself.
What is NMF made of?

Amino Acids
There are two types of Amino Acids: non-essential and essential. Non-essential Amino Acids are produced by the body (such as in NMF). Essential Amino Acids not produced by the body and must be taken in by foods and supplements. Our Serum is made with both types of Amino Acids, including Alanine, Arginine, Aspartic Acid, Glycine, Histidine, Isoleucine, Phenylalanine, Proline, Serine, Threonine, and Valine. Amino Acids work to keep the skin hydrated, strengthen the immune system, and protect skin from free radicals.
Pyrrolidone Carboxylic Acid (PCA)
Pyrrolidone Carboxylic Acid (PCA) is a humectant (a substance used to reduce moisture loss) that is part of the skin’s NMF. When applied topically, PCA helps replenish the NMF for skin that appears hydrated, smooth, and firm.
Hyaluronic Acid (HA)
Hyaluronic Acid (HA) is another powerful humectant found in the skin’s Natural Moisturizing Factor. And we mean powerful – HA can hold approximately 1,000 times its weight in water. HA works like a magnet to hold moisture, helping your skin look hydrated and healthy. When our skin is more hydrated, it appears plumper and fine lines are less visible.
Do you have questions? Comments? Topics you want us to cover? We’d love to hear from you. Email us at thelab@eighteenb.com.