GHK-Cu: what the ingredient tells you—and what it doesn’t
A guide to copper peptides, formulation context, and the limits of ingredient-level evidence.
The reading room
Ingredient Library
Understand the ingredient, then examine the evidence.
Niacinamide: a closer look at the clinical evidence
Understand one niacinamide trial and the questions to ask before applying its findings to a serum.
Ferments, filtrates, and probiotics: read the distinction
Why a fermented skincare ingredient is not automatically a live probiotic, and what evidence to look for.