January 2026 • Vol. 32 • Issue 1
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Defining ‘Microbiome-Friendly’: Why Standardization Is the Foundation for Skin-Respecting Innovation …Spyridon Markos
skin microbiome-friendly product must preserve microbial viability and function, avoid dysbiosis, and respect the skin barrier. Standardized in vitro testing provides a necessary foundation, while in vivo sequencing and functional assays add ecological and mechanistic relevance. The skin microbiome has become a defining theme in modern dermatological science, reshaping the language of cosmetic formulation and product claims. As consumers become more microbiome-aware, the industry rushes to adopt terms like "microbiome-friendly" or "biome-safe." Yet despite the surge in usage, the meaning behind these labels remains scientifically imprecise, often loosely applied without agreed-upon benchmarks.1,2 Cosmetic products can measurably alter skin microbial composition and diversity, even after short application periods, highlighting the need for clearer definitions and structured evaluation frameworks.3 It’s time we ask: what truly defines a microbiome-friendly product, and how can we measure it with rigor? At its core, a skin microbiome-friendly product is one that respects and preserves the viability, diversity, and beneficial functionality of the native skin microbiota—without tipping the ecological balance or inducing skin barrier disruption. In other words, such a product must not harm commensal microbes, must not promote the overgrowth of opportunistic or pathogenic species, must preserve functional microbial traits (like AMP synthesis or sebum metabolism),2,4-6 and must do so without causing irritation, dryness, or inflammation.7 But achieving this requires more than good intentions. It demands a structured, multidisciplinary assessment. And like all complex systems, it needs a stable foundation—a standard. Rolf Dobelli, in his essay on the "General Standardization Theory," likens standardization to replacing a fragile pile of irregular stones with interlocking bricks. While expert hands might stack ten stones high, even a child can build taller and more stably with standardized blocks. Standardization, he argues, is not just about precision—it’s about enabling collaboration, reliability, and scalable progress.8 The same logic holds true in our field. Without a standardized starting point for assessing microbiome friendliness, each lab, each brand, and each claim becomes its own unsteady tower. A robust, well-designed in vitro assay offers the most viable foundation for standardization in microbiome claim assessment. Its strength lies in its reproducibility and scalability, enabling a common technical language across laboratories, manufacturers, and regulators—similar to what was achieved with preservative challenge testing.9 To be ecologically relevant, however, the microbial panels must reflect the specific biogeography of the skin. Different anatomical regions host distinct microbial communities: sebaceous zones (e.g., face, chest) are dominated by Cutibacterium acnes; moist areas (e.g., axillae, groin) by Corynebacterium and Staphylococcus; and dry sites (e.g., forearms, legs) by more diverse and aerotolerant taxa.2,4,10 Therefore, the (continued on Page 4) development and adoption of standardized, site-specific microbial panels—whether
NYSCC, CTSCC, LISCC, & NESCC SKI TRIP • JANUARY 30 – FEBRUARY 1 ...see page 3 for more information.