Written by: Rhonda Davis
Skin isn't just a single surface, it's built from multiple distinct layers that shield the body from pathogens, help regulate our temperature and prevent excess water loss. That last job matters more than it sounds: the human body is majority water and the outermost skin layer, the epidermis, is what keeps that hydration locked in. As cells in the epidermis reach the end of their lifecycle, a structural protein called filaggrin breaks down into free amino acids and related compounds. Together, these form what's known in dermatology as the natural moisturizing factor, or NMF. This mixture of small, water-binding molecules sit in the stratum corneum (the outermost visible layer of skin) and are essential to skin hydration and barrier function.
Our hair relies on a similar principle. The hair fiber's outer layer, the cuticle, and its inner cortex both depend on amino acids to hold onto moisture and maintain structural integrity. Research in the International Journal of Cosmetic Science has shown that keratin-derived peptides and amino acids can penetrate the hair fiber and measurably improve its strength and manageability, particularly in hair that's been chemically or environmentally damaged. When hair is depleted of these amino acids, the cuticle loses its ability to hold moisture, which shows up as dryness, brittleness, and increased breakage. This is similar to the skin's barrier breaking down without enough NMF.
This is the science behind why amino acids are a core ingredient category in effective hair care, not just a label buzzword. AYIRA BEAUTY uses an amino acid blend formulated to help replenish what's lost through washing, heat styling and chemical treatment by supporting moisture retention at both the scalp and strand level. To shop our products and learn more about our ingredients, click here.
Sources
- Mechanisms of Natural Moisturizing Factors for Skin Hydration — Journal of the American Academy of Dermatology
- Oral Intake of Enzymatically Decomposed AP Collagen Peptides Improves Skin Moisture and Ceramide and Natural Moisturizing Factor Contents in the Stratum Corneum — Nutrients (PMC/NIH)
- Penetration of Different Molecular Weight Hydrolysed Keratins into Hair Fibres and Their Effects on the Physical Properties of Textured Hair — International Journal of Cosmetic Science (PMC/NIH)