Overview
Lipids are oil-like substances naturally present in the skin that play a critical role in barrier integrity, hydration and overall skin function.
Advances in skin science reveal two distinct lipid types—physiologic (Skin Identical) and non-physiologic—each affecting the skin in very different ways.
Targeted skincare rituals 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 recognised long before the field itself was formally established. Qualities of olive oil were well understood by the ancient Greeks, while even earlier agrarian societies recognised 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, non–water-soluble molecules that form a fundamental part of the skin’s natural structure. Essential to 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 ageing, over-exfoliation or environmental exposure) skin may feel dry, sensitised 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 analyse the skin 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 signal carriers, forming the skin lipid barrier within the outermost layer of the skin, the stratum corneum.
This lipid barrier function is critical. It keeps moisture in, irritants out, and directly influences the skin’s ability to grow, mature, reproduce and continuously renew corneocytes. In simple terms, PLs are what make healthy skin function properly.
At RATIONALE, we classify Physiologic Lipids as Skin Identical, because the skin recognises 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 fortify skin barrier function and support long-term hydration. The result is skin that appears calmer, clearer, and more resilient.
How ageing affects lipid stores
As we age, and as a result of cumulative environmental damage, Physiologic Lipids become depleted. This disruption to the skin lipid barrier leaves skin dry, sensitive, and increasingly vulnerable to solar and environmental harm.
Non-Physiologic Lipids (NPLs) in skincare
Non-Physiologic Lipids are not native to 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 nature, they are not recognised by the skin and do not contribute to a healthy skin lipid physiology.
Botanical lipids
Some botanical oils can play a supportive role when used with intention. Australian sandalwood oil, for example, is rich in ximenynic acid—a potent, naturally occurring anti-inflammatory lipid. It can assist in reducing 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 exhibit 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 minimising practices that strip away 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, created to restore, strengthen and nourish the skin barrier.
Meet The Nourishing Collection:
a suite of formulations rich in ceramides and Skin Identical lipids, created to restore, strengthen and nourish the skin barrier.
#4 The Nourishing PreCleanse Balm
This balm-to-oil formulation is the essential prelude to your evening cleanse, gently dissolving all traces of makeup, SPF, and environmental impurities. Intercellular lipids and ceramides work in harmony to comfort the complexion and support skin barrier restoration, making it the ideal first step in a double-cleanse routine.
#4 The Nourishing Cleanser
This award-winning cream cleanser gently purifies while preserving skin suppleness. Formulated with ceramides and intercellular lipids, it restores barrier integrity while removing SPF, makeup, dirt, and debris. Suitable as the first step in your nightly skincare ritual.
#4 The Nourishing Crème
A rich, restorative cream that replenishes essential lipids and ceramides to strengthen skin barrier function, boosting hydration and comfort while you sleep.
#4 The Nourishing Eye Crème
This luxurious eye crème brightens and nourishes the delicate under-eye area, visibly reducing fine lines, puffiness and dark circles while delivering sustained hydration. Enriched with lipids, ceramides and peptides, use this formulation morning and evening for a more rested, luminous appearance.
#4 The Nourishing Balm
Ideal for extremely dry or compromised skin, this intensely nourishing balm supports skin barrier function using intercellular lipids and ceramides. It comforts, visibly calms and protects the complexion, making it particularly suited to post-invasive treatments.
