Why Are Lipids Essential for Skin Barrier Health?
Overview
Lipids are oil-like substances naturally found in the skin that play a critical role in maintaining the skin barrier, hydration, and overall skin function.
Advances in skin science have identified two distinct types of lipids—physiologic (skin-identical) and non-physiologic—each affecting the skin in very different ways. Targeted skincare routines that replenish skin-identical lipids can help restore barrier function, reduce sensitivity, and support long-term skin health.
The history of lipids
Lipids have been used for centuries in dermatology; however, their emollient, moisture-protective properties were recognized long before the field was formally established. The qualities of olive oil were well understood by the ancient Greeks, and even earlier agrarian societies recognized the wound-healing properties of lanolin. These early observations laid the foundation for our modern understanding of lipids and their role in skin health.
The role of lipids in skincare
Lipids are oil-based, water-insoluble molecules that are a fundamental part of the skin’s natural structure. Essential for healthy skin function, they play a vital role in maintaining the skin barrier, regulating moisture levels, and protecting against environmental stressors.
When these natural lipids become depleted (through aging, over-exfoliation, or environmental exposure), skin may feel dry, sensitive, or less resilient. In skincare products, lipids are used to replenish what has been lost, restoring comfort, improving suppleness, and helping the skin maintain balance over time.
What are the different types of lipids?
In the twentieth century, advances in spectrographic technology enabled researchers to look inside the skin and analyze the lipid composition unique to humans. What emerged was a deeper understanding of lipid physiology and the vital role lipids play in maintaining skin health.
The major finding was that there are two types of lipids that affect the skin:
- Physiologic lipids (PLs)
- Non-physiologic lipids (NPLs)
What are Physiologic Lipids (PLs)?
Physiologic lipids have a biological purpose. They act as biochemical signaling carriers, forming the skin’s lipid barrier within the outermost layer of the skin, the stratum corneum.
This barrier function is critical. It helps keep moisture in and irritants out, and directly influences the skin’s ability to grow, mature, reproduce, and continuously renew corneocytes. In simple terms, physiologic lipids are what enable healthy skin to function properly.
At RATIONALE, we classify physiologic lipids as Skin Identical because the skin recognizes them and knows how to use them effectively.
Skin Identical Lipids explained
Skin-identical physiologic lipids include:
- Ceramides
- Triglycerides
- Cholesterol
These are prime examples of lipids in skincare that closely mirror the lipids naturally found in the skin.
When used correctly, these lipids can strengthen the skin barrier and support long-term hydration. The result is skin that appears calmer, clearer, and more resilient.
How Aging Affects Lipid Levels
As we age, and as a result of cumulative environmental damage, physiologic lipids become depleted. This disruption to the skin’s lipid barrier leaves the skin dry, sensitive, and increasingly vulnerable to sun and environmental damage.
Non-Physiologic Lipids (NPLs) in skincare
Non-physiologic lipids are not naturally found in the skin. These include compounds such as mineral oil and most vegetable oils. While they may reduce water loss from the skin’s surface due to their occlusive properties, they are not recognized by the skin and do not contribute to healthy skin lipid function.
Botanical lipids
Some botanical oils can play a supportive role when used intentionally. Australian sandalwood oil, for example, is rich in ximenynic acid—a potent, naturally occurring anti-inflammatory lipid. It can help reduce visible redness, dryness, and sensitivity, particularly when the skin is compromised.
How to restore skin lipids
Over years of observation, we have found that many individuals experience barrier dysfunction, often worsened by products that strip the skin of its natural lipids or rely on non-physiologic substitutes.
Skin lipids can be restored by replenishing the skin with barrier-supporting ingredients while minimizing practices that remove natural oils. Consistent hydration and gentle cleansing help create the conditions needed for the skin to rebuild and maintain a healthy lipid barrier.
Meet The Nourishing Collection: a suite of formulations rich in ceramides and skin-identical lipids, designed to restore, strengthen, and nourish the skin barrier.
Meet The Nourishing Collection:
A collection of formulations rich in ceramides and skin-identical lipids, designed to restore, strengthen, and nourish the skin barrier.
#4 The Nourishing PreCleanse Balm
This balm-to-oil formulation is the essential first step in your evening cleanse, gently dissolving all traces of makeup, SPF, and environmental impurities. Intercellular lipids and ceramides work together to soothe the skin and support barrier restoration, making it the perfect starting point for a double-cleanse routine.
#4 The Nourishing Cleanser
This award-winning cream cleanser gently purifies while maintaining skin’s suppleness. Formulated with ceramides and intercellular lipids, it restores barrier integrity while removing SPF, makeup, dirt, and debris. Ideal as the first step in your nightly skincare routine.
#4 The Nourishing Crème
A rich, restorative cream that replenishes essential lipids and ceramides to strengthen the skin barrier, enhancing hydration and comfort while you sleep.
#4 The Nourishing Eye Crème
This luxurious eye cream brightens and nourishes the delicate under-eye area, visibly reducing fine lines, puffiness, and dark circles while providing lasting hydration. Enriched with lipids, ceramides, and peptides, use this formula morning and evening for a more rested, radiant appearance.
#4 The Nourishing Balm
Ideal for extremely dry or compromised skin, this intensely nourishing balm supports the skin barrier with intercellular lipids and ceramides. It soothes, visibly calms, and protects the skin, making it especially suitable for use after invasive treatments.
