Evidence Levels
Every effect on this wiki gets two separate ratings. One says how sure we are. The other says what the trials found. A confident "no benefit" is a strong result, not a weak one.
How sure we are
Evidence | What it takes |
|---|---|
Strong | A meta-analysis, or at least two independent randomized trials, measuring the outcome itself (not a blood marker), with consistent results in a population like the one named |
Moderate | Randomized trials exist, but one problem lowers confidence: small samples, short duration, some inconsistency, or a narrow population |
Limited | One or two small trials, surrogate outcomes only, observational data, or trials that disagree |
Insufficient | Animal, cell, mechanistic or anecdotal evidence only, or no human trials |
These roughly follow the GRADE levels used in clinical research (high, moderate, low, very low).
Caps:
If every positive result comes from manufacturer-funded trials, the grade is at most Limited.
When an intervention can't be blinded (sauna, cold water, light) and the outcome is subjective (mood, stress, how recovered someone feels), the grade is at most Moderate.
Trials shorter than 8 weeks on a long-term claim lose one level.
What the trials found
Benefit, small / Benefit, moderate / Benefit, large / No benefit found / Mixed results / Not tested.
"Mixed results" means adequate trials pointing in opposite directions. A single unreplicated trial is Limited evidence, not Mixed.
Where effects go
An effect is listed under What the research supports only if trials found a benefit and the evidence is Moderate or Strong. Everything else goes under Claimed but unsupported or contested.
Why there is no single score per article
A supplement can have strong evidence for one effect and none for five others. One overall grade would average things that don't belong together, and it would read as a verdict on the product. Instead, each article opens with an evidence summary: the best-supported effect and the most-cited weak claim, each with its own rating.
Every rating names the population studied, gives a short reason for the grade, and cites at least one source. Observational associations are never described as causes. Harms are graded and cited the same way as benefits.