How we grade evidence
We grade specific health claims, not whole supplements. Each review identifies the form, population and outcome.
We assess study quality, precision, consistency and relevance. A meta-analysis does not automatically earn an A.
A grade describes confidence in the evidence. The verdict separately explains benefit size, practical relevance and safety.
What A–F means
A & B — Stronger support
A — Strong, consistent support: a substantial body of directly relevant, well-conducted human trials, with precise findings and convincing replication.
B — Reasonably convincing support: relevant human trials support benefit, with some remaining limitations or uncertainty.
C — Limited but promising
C — Limited but promising: a positive signal exists, but small effects, limited replication, short follow-up or other weaknesses prevent a confident recommendation.
D — Weak or inconsistent
D — Weak or inconsistent: available human findings conflict, are seriously limited, or do not establish the claimed benefit.
F — Insufficient human evidence
F — Insufficient relevant human evidence: there is not enough suitable human evidence to assess the claim. This does not establish that the intervention is ineffective.
Beyond the letter grade
These are our editorial grades, not a formal GRADE assessment, regulatory approval or a guarantee of benefit.
Every review also states whether evidence supports benefit, is mixed, or supports no meaningful benefit. Strong evidence of no benefit can carry a high confidence grade with an explicit negative verdict. A is not a shopping score; F does not mean “does not work”.
We consider randomisation, blinding, missing data, prespecified outcomes, precision, replication, relevance, funding and conflicts. Mechanisms and animal findings provide context but do not establish effects in people.
Reviews record the evidence-search date, sources and limitations. We distinguish a targeted review from an exhaustive systematic review and explain meaningful changes to a verdict. Affiliate arrangements do not determine grades. “Pharmacist reviewed” is used only after the named pharmacist completes the clinical review.
