Ceramides

Ceramides are lipid molecules that make up approximately 50% of the skin's outermost layer (stratum corneum). They form a protective barrier that locks moisture in and keeps irritants, bacteria, and pollution out. Think of them as the "mortar" between the "bricks" (skin cells) of your skin barrier.

Healthy skin has a high concentration of ceramides. When ceramide levels drop — due to age, harsh cleansers, exfoliation, or skin conditions like eczema and rosacea — the barrier becomes compromised. This leads to transepidermal water loss (TEWL), dryness, sensitivity, and increased susceptibility to irritation and infection.

There are 9 identified ceramides in human skin (Ceramide 1–9, also known as AP, EOP, NG, NP, NS). Most skincare products contain a mix of synthetic or plant-derived ceramides. Look for products that list multiple ceramide types (e.g., Ceramide NP, Ceramide AP, Ceramide EOP) for the best barrier repair.

• Cholesterol and Fatty Acids — the ideal ceramide ratio mimics the skin's natural lipid composition (3:1:1 ceramides:cholesterol:fatty acids). The brand Stratia's Liquid Gold is famous for this ratio. • Niacinamide — boosts ceramide synthesis naturally. • Peptides — support collagen and barrier repair. • Humectants (hyaluronic acid, glycerin) — draw water in; ceramides seal it. • Avoid using with harsh foaming cleansers that strip the barrier.

Absolutely everyone, but especially: • Dry or dehydrated skin • Eczema, psoriasis, rosacea • Over-exfoliated or damaged barrier • Ageing skin (ceramide production declines with age) • Anyone using retinol or strong actives (ceramides support barrier recovery) Ceramides are non-irritating, non-comedogenic, and safe for all skin types.

The skin's barrier lipids work in specific proportions to form the orderly lamellar structures that create effective barrier function. The ideal ratio: 1:1:1 molar ratio of ceramides:cholesterol:free fatty acids (some research points to 3:1:1 by weight — active scientific debate on exact proportions). Why ratio matters: When this ratio is disrupted — as in eczema, where ceramide levels drop disproportionately — the lamellar bodies cannot form correctly. This leads to intercellular spaces that allow irritants to penetrate and water to escape. Pioneering work by Dr. Peter Elias at UCSF demonstrated that applying all three lipid classes together in the correct ratio was necessary for effective barrier repair — applying ceramides alone was less effective than the complete combination. What this means for product selection: Look for moisturisers that contain: • Multiple ceramide types (NP, AP, EOP — at least two listed) • Cholesterol or plant-derived phytosterols • Free fatty acids: stearic acid, linoleic acid, or plant oils rich in these (sunflower, rosehip) Products that nail the ratio: CeraVe (ceramides + cholesterol), Stratia Liquid Gold (specifically formulated around lamellar body ratio), La Roche-Posay Lipikar.

After age 40, ceramide production in the skin decreases significantly — and this isn't just a cosmetic concern. Ageing and ceramide loss: Research published in the British Journal of Dermatology found that total ceramide content in the stratum corneum decreases measurably with each decade after age 30. By age 60–70, ceramide levels can be 30–40% lower than in young adult skin. Consequences of age-related ceramide decline: • Increased TEWL (water loss) — skin feels perpetually dry • Thinner, more fragile barrier — easier penetration by irritants • Slower barrier recovery after disruption • Increased sensitivity to previously tolerated products and environmental factors • Worsening eczema, rosacea, or general skin reactivity Topical ceramides help but don't fully replace endogenous production. Niacinamide applied topically has been shown to upregulate ceramide synthesis — making it one of the best long-term companions to direct ceramide application. Practical action: Over-40 skin benefits from daily ceramide application in both AM and PM moisturisers, not just as an occasional treatment. Consider a thicker ceramide-rich cream at night and a lighter ceramide formula during the day under SPF.

Ceramides appear on INCI lists under several names — knowing these helps you assess products quickly: Full ceramide names on labels: • Ceramide NP (also Ceramide 3) — the most common in skincare • Ceramide AP (also Ceramide 6-II) — key for barrier recovery • Ceramide EOP (also Ceramide 1) — longest chain, critical for lamellar structure • Ceramide NG (also Ceramide 2) • Ceramide NS (also Ceramide 7) Where ceramides should appear: For therapeutic barrier repair, ceramides should appear in the first half of the ingredient list. Products where ceramides appear near the bottom may not contain enough to make a meaningful difference. Pseudo-ceramides and ceramide precursors: Some products use ceramide precursors (sphingosine, phytosphingosine) that the skin converts to ceramides. Plant-derived ceramides (hexadecyl ceramide, wheat-derived ceramides) are also used — research suggests they are incorporated into the barrier lamellar structure similarly to human ceramides.