Understanding Peptide Evidence Tiers
Research & educational use only. This content is not medical advice. Consult a qualified healthcare professional before using any peptide compound.
Every compound in the PeptidesHub database carries an evidence tier — a quick signal for how strong the human evidence actually is. The tiers exist because anecdote and clinical data too often get presented with equal visual weight. Understanding what each tier means lets you calibrate confidence before you read a single thread.
What do the four evidence tiers mean?
- Tier 1 — RCT evidence. Supported by human randomized controlled trials, the strongest practical evidence for cause and effect. GLP-1 analogs like semaglutide and tirzepatide sit here.
- Tier 2 — Observational. Supported by human observational studies or clinical reports without randomization. Suggestive, but more vulnerable to bias and confounding.
- Tier 3 — Animal only. Evidence limited to animal models. Mechanistically interesting, but animal results frequently fail to translate to humans.
- Tier 4 — Theoretical. A mechanistic or theoretical rationale with little or no controlled data.
Why does randomization matter so much?
Randomized controlled trials randomly assign participants to treatment or control, which balances out both known and unknown confounders. That design is what lets researchers attribute a difference in outcome to the intervention rather than to who happened to take it. Observational data can’t make that claim as cleanly, which is why it sits a tier lower.
How should I read the trial counts?
Each compound page lists the number of human randomized controlled trials and the combined number of subjects enrolled, plus the count of animal studies. A compound with zero human RCTs and dozens of animal studies is, by definition, Tier 3 — the volume of animal work does not promote it. Pay attention to enrollment: a single small trial is weaker evidence than several large ones.
What about FDA status?
FDA approval status is shown separately from the evidence tier because they answer different questions. Approval reflects a regulatory decision about a specific indication; the evidence tier reflects the underlying research base. A compound can have a strong evidence base for one use and no approval for another.