Evidence grading methodology
A consistent way to label evidence on every Peptide Authority page. Five letters for evidence strength (A–E), plus two flags for regulatory risk (R) and sport risk (S). The same grades appear in summary cards, claim-vs-evidence tables, and the top of every peptide page.
The seven grades
A — Strong human evidence
Licensed medicine and/or systematic reviews of randomised human trials.
Example use: Semaglutide for type 2 diabetes — multiple large human RCTs, regulator-approved indication, NICE guidance, NHS access route.
B — Moderate human evidence
Multiple human trials, some inconsistency or limited size.
Example use: Tesamorelin for HIV-associated visceral adiposity — licensed medicine in some jurisdictions with positive but more limited human evidence base.
C — Limited human evidence
Few small human studies; outcomes uncertain.
Example use: Selank for situational anxiety — a small number of mostly Russian-language human studies, limited replication, evidence quality is mixed.
D — Animal/cell evidence only
Preclinical (animal or in vitro) data only. Human relevance unproven.
Example use: BPC-157 for tendon recovery — promising animal data, no robust human RCTs at the time of writing. Mechanism-rich, evidence-light.
E — Theoretical / insufficient
Mechanism, anecdote, or theory only. No reliable evidence.
Example use: Many claimed 'longevity stacks' — theoretical pathway arguments and supplement-marketing copy, without trial data in humans.
R — Regulatory risk
Unlicensed for human use and/or unclear UK regulatory status.
Example use: Retatrutide marketed direct-to-consumer — investigational compound, no UK licence, sold by some online sellers as 'research only'. High regulatory risk.
S — Sport/doping risk
Prohibited or potentially prohibited under WADA / sport anti-doping rules.
Example use: BPC-157 in athletes — treated by WADA as prohibited under the S0 non-approved substances category. Strict-liability rules apply.
How we assign grades
- A: licensed medicine and/or high-quality systematic reviews of human RCTs.
- B: multiple well-conducted human trials with broadly consistent findings, but some limitations of size, follow-up, or replication.
- C: a small number of human trials, with inconsistent or hypothesis-generating findings.
- D: animal and / or in-vitro evidence only. Mechanism may be plausible, but human relevance is unproven.
- E: theoretical claim, anecdote, marketing copy, or mechanistic speculation only — no reliable evidence.
- R: regulatory risk flag — unlicensed for human use in the UK and/or unclear regulatory status. Often applied alongside an evidence grade.
- S: sport / anti-doping risk flag — prohibited or potentially prohibited under WADA / UKAD rules. Often applied alongside an evidence grade.
What the grades do not mean
- An A grade does not mean a compound is safe for you. It means evidence and licensing for a specific indication is strong.
- A D grade does not mean a compound definitely “works in mice but not humans” — it means we currently have no good human evidence to judge.
- The R flag is not legal advice. UK regulatory status changes; verify with the MHRA.
- The S flag is not a substitute for checking the WADA Prohibited List with a qualified anti-doping advisor.
Versioning & updates
This methodology is versioned. Material changes to the grading scale are recorded here with the date and the reason. The current scale is version 1, published with the Phase 1 trust architecture build.
See this in practice
Every peptide page on Peptide Authority renders a standard 20-module Evidence Standards Summary built from this methodology — evidence snapshot, human vs preclinical grades, regulatory status, approved vs unapproved claims, claim-vs-evidence, safety / interaction uncertainty, anti-doping status, UK / EU legal position, what the page cannot tell you, citation quality, research gaps, safer alternatives, and doctor discussion prompts.
- Sample on BPC-157 →
- Sample on Semaglutide (Wegovy / Ozempic) →
- Sample on Tirzepatide (Mounjaro) →
- Sample on Melanotan II →
Peptides without seeded structured data still render the panel with honest fallback text — “Not yet graded — see methodology”, “Drug-interaction picture not characterised”, etc. — so the structure is consistent across every peptide.
Related: editorial standards · UK regulatory methodology · medical disclaimer.