How we grade the evidence.
Every ingredient and product on KÖGN carries a letter grade from A+ to C. The grade is KÖGN Health’s editorial assessment of the published research — how much there is, how good it is, and how consistently it points the same way. It is never a health claim.
What counts as evidence
Controlled human trials carry the most weight — randomised, placebo-controlled studies at doses people actually take, in populations like the one the claim is made for. Small or short human studies count for less. Cell and animal work is a starting point, not a conclusion: it can justify interest, never a top grade.
Where the evidence is mixed or absent, the entry says so directly. Promising and proven are never the same thing on this site.
The scale
- A+
Strong evidence
Strong, consistent evidence. Multiple controlled human trials at sensible doses, with effects replicated across studies and populations.
- A
Strong evidence
Strong evidence. Several controlled human trials point the same way, with minor gaps — fewer replications, or effects clearest in specific contexts.
- A-
Strong evidence · not currently in use
Strong-to-moderate evidence. Good human data for a defined use case; less consistent outside it.
- B+
Moderate evidence
Moderate evidence. Promising controlled human trials, but fewer, smaller, or shorter than the grades above.
- B
Moderate evidence
Moderate, mixed evidence. Some human trials show benefit and others do not; effects are typically modest or population-specific.
- B-
Emerging evidence · not currently in use
Emerging evidence. Limited human data — early trials, small samples, or strong mechanistic work that has not yet been confirmed in people.
- C+
Limited evidence
Preliminary evidence. Mostly preclinical (cell or animal) findings, with at best isolated human data.
- C
Limited evidence · not currently in use
Weak or preliminary evidence. Anecdote, tradition, or laboratory findings only — interesting, but not yet evidence of effect in healthy adults.
How grades are updated
Grades are revisited as new research is published, and the corpus is reviewed as a whole when the underlying database is updated — most recently in June 2026. A grade can move in either direction; several have.
Grades are applied to the ingredient as studied — at the doses and durations the research used. A product that includes a well-graded ingredient at a fraction of its studied dose does not inherit the grade, which is why product reviews are graded on what is actually inside.
Educational information, not medical advice. Evidence grades are KÖGN’s editorial assessment of published research, not health claims. Speak to a qualified clinician before changing what you take.