Beyond Count: The Concentration Gate
While an ingredient might have 50+ studies (Strong Tier), it only works if it's present in the product at the correct concentration. Korean Pharmacists (Yaksa) frequently highlight that many "cosmetic" products use trace amounts ("fairy dust") for marketing, while "Clinical Grade" products meet the specific PPM (Parts Per Million) thresholds proven in clinical papers.
Products with the ✨ badge have either disclosed concentration matching clinical papers or have been verified as pharmacy-grade staples.
Our 10 sources
We pull from databases that cover skincare research and regulators worldwide, well beyond Western dermatology. Each name links to the underlying database or regulator's own site (645 citations, primarily from PubMed (630) plus 9 additional regulatory and regional databases including KCI, Cochrane, and MFDS):
Counts grow as we add citations on a rolling basis. Every database listed here has at least one specific citation behind it; we do not count a source until it does. Chinese (Chongqing VIP) and French (SFD / Annales de Dermatologie) coverage is in active expansion for K-beauty botanicals and pigment-correction research.
How an ingredient gets in the database
- Two editors independently identify candidate ingredients from journal scans + reader requests.
- We pull every relevant citation (RCTs, in-vitro, in-vivo) and tag by study quality.
- An ingredient needs at least 3 peer-reviewed sourcesacross at least two databases before it's added.
- Tier is assigned by total study count + presence of RCTs + mechanism confirmation.
- Every claim on every page must link back to one of the cited papers. No exceptions.
How tiers can change
An emerging ingredient moves to "moderate" once it crosses 5 peer-reviewed studies including at least one controlled trial. Moderate moves to "strong" when one of two thresholds is met: 15+ studies including multiple RCTs, or a single large longitudinal cohort study (something like 50+ subjects followed for 12+ months with controlled measurement against baseline). One solid real-world cohort can carry as much weight as a stack of small trials when the methodology is sound. We re-review every ingredient in the database quarterly.
What we don't do
- We don't accept industry-funded studies as the sole source for a tier upgrade.
- We don't cite blogs, Reddit threads, or product marketing pages.
- We don't cite an LLM as a source. Ever.
- We don't let affiliate revenue influence recommendations. When you buy through a product link, we earn a small commission from the retailer (the price to you is identical). That relationship never changes which ingredients we recommend or how products are ranked. Full disclosure.