Evidence methodology
Every compound on VialBase carries a four-tier evidence rating. Here is exactly how those ratings are assigned.
Evidence tiers
Four tiers, assigned by reviewing the full body of available research, not cherry-picked studies. Each tier describes a research state, not a recommendation.
Multiple replicated human clinical trials with adequate sample sizes demonstrating consistent, statistically significant effects. Results hold across independent research groups and study designs.
Some human data exists but trials are limited in number, sample size, or have methodological constraints. Results are generally positive but full replication is lacking. Mixed results across studies may be present.
Research is primarily from animal models, in vitro cell studies, or a single small human pilot. Effects are biologically plausible but human translation has not been established. Treat as exploratory.
No published research or only preclinical mechanism studies. Effects reported exclusively through user accounts, forums, or vendor claims. No controlled data available to evaluate.
Rating criteria
Each rating considers the following factors in aggregate. No single criterion determines the tier:
- Human trial count: number of independent randomized or controlled trials in humans.
- Sample sizes: adequately powered trials (n ≥ 30 preferred for systemic outcomes).
- Replication: independent labs or research groups reproducing results.
- Study quality: randomization, blinding, control group, and appropriate endpoint selection.
- Species relevance: rodent studies weighted lower than primate or human; in vitro weighted lowest.
- Recency: older research without recent confirmation is weighted down.
- Conflict of interest: vendor-funded studies noted and weighted accordingly.
Limits of this system
Evidence ratings are editorial judgments based on available literature at the time of last review. They are not FDA determinations. The research landscape changes. If you find a study we missed, contact us.
A "Strong" rating means the effect is well-replicated, not that the compound is safe for a given person. Safety, legal status, and individual risk profile are separate questions, covered on the relevant compound page and in the disclosure.