Combating Environmental Pollutants by Nurturing the Lipid Matrix of the Stratum Corneum & Supporting Skin Barrier Function: Overview
The stratum corneum is the outermost layer of the epidermis, and it houses a lipid matrix that plays a critical role in skin barrier function and in minimizing the entry of ROS (Reactive Oxygen Species)-inducing factors such as environmental pollutants or other external stressors. In this article, we discuss possible downstream effects of external stressors on a compromised skin barrier, and we dive into how tallow, through its lipid biocompatibility, can support skin barrier function by supporting the lipid matrix of the stratum corneum. We will finish the conversation by going through an absolutely remarkable line, expertly formulated to support the skin, hormones, and more.
Skin Barrier Function & Anatomy:
Skin barrier function includes the skin's ability to regulate water loss, prevent the entry of harmful substances, and protect against microbial invasion, environmental pollutants, and physical damage. This critical function is largely attributed to the stratum corneum, the outermost layer of the epidermis, which consists of anucleated corneocytes embedded in a lipid matrix composed of ceramides, cholesterol, and free fatty acids. The corneocytes, often described as the "bricks," are reinforced by the cornified envelope, a structure formed by proteins including involucrin and loricrin, while the intercellular lipids serve as the "mortar," providing the hydrophobic barrier that prevents transepidermal water loss (TEWL) and aids in blocking the penetration of irritants and pathogens.
This outermost stratum corneum described above is one of the many layers comprising the epidermis. The epidermis is a multilayered structure that shields the body from an array of environmental insults and is composed of five distinct layers, starting with the stratum basale, which rests on the basement membrane—a thin layer that separates the epidermis from the dermis. This layer is home to basal keratinocytes, which are progenitor cells that continuously divide to generate new keratinocytes, ensuring the epidermis is replenished. These cells are anchored to the basement membrane by hemidesmosomes, specialized adhesion structures that provide mechanical stability and maintain the integrity of the epidermis-dermis connection. Additionally, the stratum basale contains melanocytes, which distribute melanin to keratinocytes for UV protection. Merkel cells, mechanoreceptors sensitive to fine touch, are also found in this layer, contributing to the sensory functions of the skin.
Above the stratum basale lies the stratum spinosum, also known as the "prickle cell layer" due to keratinocytes' spiny appearance under a microscope. These spiny projections are caused by desmosomes, intercellular junctions composed of proteins like desmogleins and desmocollins, which tightly link keratinocytes together, providing structural cohesion and mechanical resilience. This layer enables the epidermis to withstand physical stresses such as stretching and friction. The stratum spinosum also contains Langerhans cells, immune cells that patrol the epidermis, capturing and presenting antigens to the immune system, which initiates defense mechanisms against potential pathogens. As keratinocytes migrate upward through this layer, they begin synthesizing keratohyalin granules, which contain proteins necessary for barrier formation, and lamellar bodies, which are vesicles rich in lipids and barrier-fortifying antimicrobial peptides, eventually forming the lipid matrix largely found in the stratum corneum.
Above the stratum spinosum lies the stratum granulosum where keratinocytes undergo significant biochemical transformations. The cells flatten and become densely packed with keratohyalin granules, rich in structural proteins including loricrin and involucrin, which are essential for forming the cornified envelope mentioned previously. As keratinocytes progress through the stratum granulosum, they undergo apoptosis, programmed cell death, where they lose their nuclei and other organelles. These anucleated cells transition into corneocytes, which form the outermost layer of the epidermis, the stratum corneum.
Barrier Disruption & Reactive Oxygen Species Generation
As noted above, the skin possesses a robust protective system designed to safeguard its structure and function, with the stratum corneum serving as the primary physical barrier. Additionally, the skin is equipped with an intricate antioxidant defense system, dispersed throughout the epidermis and dermis, that neutralizes reactive oxygen species (ROS) to maintain redox homeostasis and protect cellular and structural components from oxidative damage. Epidermal and dermal cells are continuously exposed to reactive oxygen species (ROS), which are byproducts of normal cellular metabolic processes, such as oxidative phosphorylation within mitochondria. These ROS are essential at low levels for cellular signaling and defense; however, when their production exceeds the capacity of antioxidant defenses, they can cause oxidative stress. This stress is exacerbated by external environmental factors, such as airborne pollutants, including particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs), which can penetrate the skin and generate free radicals.
In more detail, antioxidant levels in the skin are critical for maintaining cellular homeostasis and mitigating oxidative damage caused by reactive oxygen species (ROS), which are generated through endogenous metabolic processes and external insults such as pollution. When the skin’s antioxidant defense system, including enzymes such as superoxide dismutase (SOD) and glutathione peroxidase, as well as non-enzymatic antioxidants including vitamin E, is depleted, excessive ROS can lead to lipid peroxidation, protein oxidation, and DNA damage. This oxidative stress can trigger activation of NF-κB, a transcription factor that upregulates pro-inflammatory cytokines, which may contribute to skin inflammation and further visual cues such as redness in some cases.
As briefly noted earlier, upstream of the antioxidant defense system within the epidermis and dermis, the lipid matrix of the stratum corneum plays a critical role in reducing environmental insults and external stressors. This matrix is composed of ceramides, cholesterol, and free fatty acids, which are arranged in a highly organized lamellar structure between corneocytes. In more detail, these lipids form a hydrophobic barrier that aids in preventing the penetration of environmental pollutants, allergens, and microbial pathogens. Therefore, the lipid matrix aids in minimizing the entry of certain ROS-inducing factors into the deeper layers of the epidermis.
Skin dryness can be characterized by a reduction in the lipid content of the stratum corneum, particularly the lipid matrix. When the skin is dry, the depletion of these essential lipids disrupts the lamellar organization of the matrix, leading to increased permeability and structural gaps between corneocytes. This impaired barrier function enables easier penetration of irritants, allergens, and microbial pathogens. In other words, disruption of the lipid matrix can lead to increased barrier permeability, allowing these external insults to more easily penetrate the skin, potentially contributing to oxidative damage in the underlying structures. Thus, maintaining hydrated skin and the integrity of the stratum corneum's lipid matrix is important for maintaining a strong barrier, minimizing oxidative stress, and preventing inflammation and damage caused by environmental stressors.
Tallow & The Stratum Corneum
Tallow, a rendered form of animal fat, is composed predominantly of triglycerides hydrolyzed into free fatty acids, glycerol, and other lipid derivatives upon contact with the skin. Its lipid profile is rather structurally compatible with the lipids naturally present in the extracellular matrix of the stratum corneum, making it an excellent emollient that can support stratum corneum barrier function and lipid matrix integrity. Its combination and ratio of saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, and more make it a truly remarkable and biocompatible lipid source that can support skin hydration and barrier function. Furthermore, the presence of antioxidants and fat-soluble vitamins within tallow further lends to tallow's incredible composition.
Ulyana Organics:
Ulyana Organics has a truly phenomenal Tallow Butter showcasing an exceptional fusion of ancestral expertise and dermatological research, offering remarkable support for the lipid matrix of the stratum corneum. It harnesses the bioadaptive properties of grass-fed, grass-finished tallow, biomimetically mirroring the composition of the extracellular lipid matrix within the epidermis. These bio-compatible lipids are truly exceptional in their ability to seamlessly integrate with the skin’s lipid matrix, exemplifying Ulyana Organics’ incredible dedication to fortifying the natural barrier and enhancing epidermal barrier function.
In addition to their Tallow Butter, Ulyana Organics has a multitude of other truly remarkable, handmade, tallow-based products including Tallow Lip Balm, Tallow Wild Yam Cream (with phenomenal ingredients such as wild yam, chaste berries, and red clover, expertly-formulated to support hormonal health), and much more. Ulyana Organics' grass-fed and grass-finished beef tallow is also sourced from regenerative farms; and alongside the grass-fed and finished tallow, they utilize such exceptionally-sourced, certified organic herbs and oils. Ulyana Organics’ unwavering dedication to purity, sustainability, and regenerative ingredient sourcing is a true testament to their scientifically-advanced yet holistically-grounded skin nourishment. For those seeking skin barrier support and epidermal longevity, their formulations are an indispensable cornerstone.
A true embodiment of meticulously-crafted, tallow-based, skin-supporting formulations merging both ancestral wisdom and modern scientific expertise: Go and experience Ulyana Organics at holisticbyulyana.com, and use code CHLOE10 to get 10% off.
*Always consult with a licensed medical professional for all of your medical needs.
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