Our evidence-grading methodology

Every ingredient is graded A to D (or NE: Not Evaluated) using a four-layer evidence model applied to a fixed rubric.

The four layers

1. Certification layer. Third-party certification bodies (NSF Certified for Sport, Informed Sport, USP Verified, IFOS) test specific products at the batch level for label accuracy, purity, and banned-substance absence. We track which products appear in each public registry, when we observed them, and link back to the registry.
2. Published lab-test layer. Independent or industry-funded published analytical tests (e.g., HPLC label-claim testing) are sourced from verifiable public records. Every row names who conducted the test, when it was published, and carries a link to the primary source. We did not run these tests.
3. Human evidence layer. Human research evidence (RCTs, controlled studies, observational data) is graded A (strong RCT support) through D (animal/cell studies only), following the rubric on this page. A reviewer applies the rubric and confirms or overrides the draft grade, recording their reasoning.
4. Expert-stack layer. We track publicly stated supplement use by researchers and practitioners (e.g., stated dose, stated rationale, and the expert's own primary source). Attribution only; no endorsement implied.

What we do and do not do

We track and aggregate third-party testing and certification (NSF, Informed Sport, USP, published lab tests) and human research evidence. We do not run the tests ourselves. Our grades reflect a reviewer's editorial synthesis of the cited evidence, not a systematic review or meta-analysis, and are not medical advice.

Grade definitions

• A Strong support from multiple well-designed randomized controlled trials (RCTs) in humans for the stated use.
• B Moderate support from at least one RCT or multiple well-controlled human studies.
• C Limited or mixed human evidence; controlled or observational studies without consistent RCT replication.
• D Animal or cell-study evidence only, or insufficient human data.
• NE Not evaluated against this rubric for this use.

Independence

No supplement brand, retailer, or certification body pays for a grade or ranking. Grades are assigned from the literature by the editorial team. Affiliate relationships (see Affiliate Disclosure) are strictly separate from the grading process.

Corrections

To report an error in a grade or summary, use our contact form.