Going Beyond Ceramides in Moisturizers: The Role of Natural Moisturizing Factors

June 2024 | Volume 23 | Issue 6 | 466 | Copyright © June 2024


Published online May 29, 2024

doi:10.36849/JDD.8358

Hilary Baldwin MDa, James Del Rosso DOb

aAcne Treatment and Research Center, Brooklyn, NY 
bJDR Dermatology Research Center, Las Vegas, NV

Abstract
Xerosis is experienced by almost everyone at some time in their lives and the foundation of management of dry skin (both consumer- and healthcare professional--directed) rests on the use of moisturizers. Given the wide range of available moisturizers, counseling patients about selecting the optimum moisturizer for their individual situation relies on knowledge of ingredients and formulations. Traditionally, the main focus for many moisturizers centered on the core functional and structural role of ceramides within the epidermal barrier.  However, while a key aspect of transepidermal water loss and other skin barrier functions, components other than ceramides are equally essential in increasing moisturization. The skin's natural moisturizing factors (NMFs) are a complex mixture of water-attracting compounds such as amino acids, urea, lactate, pyrrolidone carboxylic acid (PCA), and electrolytes which play a fundamental role in preserving physiologic function by regulating the water content of the stratum corneum. By facilitating water retention, NMFs contribute significantly to the suppleness, elasticity, normal desquamation, and overall integrity of the skin barrier. Incorporation of NMFs into moisturizers addresses critical deficiencies in the skin's moisture balance that exist in xerotic and atopic skin, and in many skin disorders, mitigating signs and symptoms associated with xerosis and promoting optimal skin health. The biochemical composition of NMFs and the intricate interplay with epidermal homeostasis translate to a central role in moisturizers used for prophylactic and therapeutic management of various dry skin conditions, beyond ceramides alone.

J Drugs Dermatol. 2024;23(6):466-471.     doi:10.36849/JDD.8358

INTRODUCTION

The majority of people experience xerosis during their lifetime and the condition can be acute or chronic.1,2 Both endogenous and exogenous factors contribute to the development of xerosis (Figure 1).3 Xerosis can occur due to changes in the environment, skincare regimen, age, medications, hereditary disorders such as ichthyosis, or secondary to inflammatory skin conditions such as atopic dermatitis, psoriasis, and seborrheic dermatitis.2,4-6 Clinically, signs of xerosis include scaling, white/flaky skin, cracks and fissures, erythema, hyperkeratosis, and lichenification. Symptoms of xerosis commonly include pruritus, which can be a significant and chronic problem in older individuals.7 Other signs and symptoms of xerosis range from the physical sensation of dryness or discomfort of the skin to pain or stinging.8 Deficiencies of several individual molecules and structural components in the epidermis can contribute to xerosis, including NMFs and ceramides; abnormalities in the skin's moisture network also play a role.9,10

The impact of xerosis is increasingly appreciated by healthcare professionals, particularly as the population ages, since dry skin in older patients can lead to problems that can be significant.11 For example, excoriation of dry, pruritic skin can lead to infection, fragile and dry or cracked skin in individuals with poor mobility can lead to pressure ulcers, and in those with insulin-dependent diabetes, dry skin can be a precursor to foot erosions and infections.11 Dry skin may also be a sign of malnutrition among elderly individuals.11

Role of Moisturizers in Xerotic Conditions
Moisturizers serve as the foundation of the management of xerotic conditions.8 These products can have both short- and long-term effects on skin hydration, barrier function, skin texture, elasticity, and appearance.8 Incorporation of specific ingredients into moisturizer formulations can enhance some of these beneficial effects.12 Over the years, there have been significant advances in the development of moisturizers, from occlusives formulated as basic skin barrier protection to humectant-enriched moisturizers developed for hydrating care.8 Occlusives are substances that form a confluent layer on the skin surface, physically blocking the evaporation of water (transepidermal water loss) and can shield the skin from irritants, allergens, and pathogens. Commonly used occlusives include oils (eg, soybean oil, olive oil, and mineral oil), waxes (eg, carnauba and beeswax), dimethicone, lanolin, and petrolatum.8 Emollients are saturated and unsaturated lipids (eg, colloidal oatmeal, shea butter, and isopropyl palmitate)