GlowGraded
Get personal advice

How we grade evidence

Every piece of advice on GlowGraded carries a grade from A to D. The grade says how strong the research behind it is, not how big the effect is.

The grades

Grade A: Strong evidence
Strong evidence
Consistent meta-analyses, systematic reviews or several RCTs.
Grade B: Moderate evidence
Moderate evidence
A few RCTs or strong observational evidence.
Grade C: Limited evidence
Limited evidence
Small or observational studies only.
Grade D: Expert opinion
Expert opinion
Mechanism or expert opinion only. We say so plainly.

Study designs, strongest first

Our research search filters to strong designs by default and ranks stronger evidence higher.

  1. 1Cochrane review
  2. 2Meta-analysis
  3. 3Systematic review
  4. 4RCT
  5. 5Clinical trial
  6. 6Observational
  7. 7Narrative review
  8. 8Other

Our rules

No advice without evidence
Every recommendation cites at least one peer-reviewed source that has not been retracted.
Stronger designs count more
Reviews that pool many studies outweigh single studies. Citation counts are context, not proof that a finding is true.
Retractions are permanent
If a journal, Europe PMC, OpenAlex or our editors flag a paper as retracted, it is removed from our search and from every recommendation, and it stays removed.
We never overstate
Effects are described the way the studies report them, with the kind and length of study, never as guarantees. Where it matters, we say who was studied: age, sex, skin or hair type.
Every claim is traceable
Each source keeps its DOI or PubMed ID, so you can read the original paper.
Respectful by design
Our advice is about health and confidence. We do not rank ethnic features, shame bodies, or write for minors.

Where the research comes from

We collect papers from Europe PMC, which includes PubMed and Cochrane reviews, and add citation and retraction data from OpenAlex. We only use free, public sources whose licences allow it.