Serine is a naturally occurring amino acid, found in both the skin and many plant and animal proteins. It is a critical component of the Natural Moisturizing Factor (NMF), the mix of molecules that keep the skin’s outer layer hydrated, supple, and resilient. As a skincare ingredient, serine is prized for its water-binding capacity, soothing effect, and ability to accelerate barrier recovery. In Terra’s barrier repair serum, serine is integral to the formula’s promise of deep hydration, barrier support, and enhanced comfort for sensitive or stressed skin【1】【2】.

Skin Benefits

1. Deep Hydration
Serine is one of the most abundant amino acids in the skin’s NMF, directly responsible for drawing and retaining moisture in the stratum corneum. This leads to plumper, softer, and better-hydrated skin【3】.

2. Barrier Repair and Maintenance
Serine supports the synthesis of structural proteins such as filaggrin, which are vital for the formation and maintenance of the skin barrier. By helping maintain the integrity of the barrier, serine reduces transepidermal water loss (TEWL) and protects against environmental irritants and allergens【4】【5】.

3. Soothing and Calming
Topical serine has been shown to help calm irritated or sensitive skin, thanks to its moisturizing and restorative effects. It is especially useful for barrier-compromised, dry, or inflamed skin【2】【4】.

Mechanism of Action

• Water-Binding: Serine’s hydrophilic side chain attracts and holds water molecules, replenishing the skin’s moisture reservoir and mimicking the skin’s natural hydration processes【3】.

• NMF Replenishment: By supplementing the NMF with extra serine, topical products help counteract the loss of hydration associated with aging, environmental stress, or over-cleansing.

• Barrier Protein Support: Serine is required for the production of filaggrin and other structural proteins, which organize the skin’s “brick and mortar” structure, ensuring a robust, well-sealed barrier【5】.

Clinical Support

A 2016 study in Skin Pharmacology and Physiology found that serine-enriched creams significantly improved skin hydration, reduced TEWL, and enhanced overall barrier function in subjects with dry, sensitive, or atopic skin【3】. Another review in the International Journal of Cosmetic Science notes serine’s unique role in replenishing NMF and promoting recovery from irritation【2】.

Synergy with Terra Ingredients

• With Proline and Arginine: Serine acts in synergy with other amino acids (proline, arginine) in Terra’s formula to comprehensively mimic and replenish NMF, maximizing hydration and barrier repair.

• With Hydrolyzed Proteins: The combination of free amino acids and protein hydrolysates in Terra ensures both immediate and long-term barrier and hydration benefits.

• With Ceramides: While ceramides restore lipid structure, serine and other amino acids restore the water-holding and protein components, ensuring a holistic approach to barrier health.

Safety and Tolerability

Serine is a normal component of human skin and is exceptionally safe for topical use. It is hypoallergenic, non-irritating, and appropriate for all skin types, including sensitive, dry, and compromised skin【1】【3】.

Connection to Terra’s Claims

• Natural Moisturizing Factors: Serine is a direct NMF component, ensuring long-lasting hydration.

• Barrier Repair: Helps build and maintain key barrier proteins, reducing sensitivity and TEWL.

• Comfort and Recovery: Supports calm, resilient skin and rapid recovery from external stress.

Key Takeaways

• NMF Hero: Serine replenishes one of the most important moisturizing molecules in the skin, providing deep and lasting hydration.

• Barrier Builder: Supports production of essential barrier proteins, boosting skin’s defenses.

• Soothing Support: Calms sensitive or stressed skin and accelerates barrier repair.

• Safe for All: Highly tolerated by all skin types, including the most delicate and reactive.

References

1. Cosmetic Ingredient Review Expert Panel. (2022). Safety Assessment of Serine as Used in Cosmetics. International Journal of Toxicology, 41(Suppl 1), 23S-28S.

2. Kim, S., & Kim, S. (2018). Amino acids and their derivatives as moisturizing ingredients in cosmetic formulations. International Journal of Cosmetic Science, 40(6), 542-550.

3. Lodén, M., et al. (2016). Effects of topical serine on skin barrier and hydration in atopic dermatitis. Skin Pharmacol Physiol, 29(1), 27-34.

4. Harding, C. R., & Scott, I. R. (2002). Amino acids in stratum corneum and their role in skin hydration. Journal of Dermatological Science, 29(3), 195-205.

5. Brown, S. J., & McLean, W. H. (2012). One remarkable molecule: filaggrin. Journal of Investigative Dermatology, 132(3), 751–762.