For your skin
SK-II's signature ingredient, a specific yeast filtrate that improves clarity and texture over time.
Want the science? Keep reading ↓Mechanism of action
Specific Galactomyces ferment filtrate strain from sake brewing; amino acids and organic acids that improve skin clarity.
Why we tier this moderate
4 cited papers across 2 countries. The mechanism is well-described and there's at least one controlled trial in the literature, but we tier this Moderate rather than Strong to stay honest about how many specific papers we cite directly.
Cited research
Miyamoto K et al., Significant Reversal of Facial Wrinkle, Pigmented Spot and Roughness by Daily Application of Galactomyces Ferment Filtrate-Containing Skin Products for 12 Months—An 11-Year Longitudinal Skin Aging Rejuvenation Study, Journal of Clinical Medicine 2023;12(3):1168 — Pitera is SK-II's commercial name for GFF; this 11-year longitudinal study directly evaluates the same active
Nakajima H et al., Transcriptomic Analysis of Human Keratinocytes Treated with Galactomyces Ferment Filtrate, a Beneficial Cosmetic Ingredient, Journal of Clinical Medicine 2022;11(16):4645 — GFF activates AhR/NRF2 antioxidant pathways while suppressing inflammatory transcripts
Anwar AI et al., The effectiveness of Galactomyces ferment filtrate, dexpanthenol, and Centella asiatica combination serum in the treatment of post-acne hyperpigmentation in subjects with skin of color, Skinmed 2021;19(2):110-115 — Pitera is SK-II's commercial name for Galactomyces ferment filtrate; trial covers the same active
Miyamoto K et al., Daily Fluctuation of Facial Pore Area, Roughness and Redness among Young Japanese Women; Beneficial Effects of Galactomyces Ferment Filtrate Containing Antioxidative Skin Care Formula, Journal of Clinical Medicine 2021;10(11):2502 — same trial documents Pitera-class GFF formula efficacy in Japanese women
Sources: 10 clinical journals and regulatory databases across the US, EU, Korea, Japan, and China. Every entry points to a specific document. See methodology for the full list and what each outcome label means.