How we grade evidence

Three grades, one rule set

Every supplement gets an overall evidence grade, and every specific claim about it gets its own. The tiers are:

• Strong — multiple randomized controlled trials and/or consistent meta-analyses point in the same direction.
• Moderate — the evidence is positive but mixed, or it holds only in a specific population.
• Limited — few studies, small studies, or mostly negative results.

Claims are graded separately because a single grade for a whole substance hides the useful part. The same supplement can sit at "moderate" for one outcome and "limited" for the three other things it is marketed for.

What the rules actually produce

Of 511 supplements, 22 are graded strong — a little over four percent. That number is the simplest test of whether the tiers mean anything. Rules that hand out top grades freely are not rules, and a catalog where most items "work" is a sales list. We publish the distribution because it is the least flattering and most informative thing about the catalog.

References and verification

The catalog cites more than 1,100 references, and every one is a real, PubMed-indexed paper. Before publication, each citation is checked against PubMed's own API: the title and the PMID have to match a record that exists. Anything that fails the check does not get published — it is corrected or removed, never left in as an approximation. Entries are then re-audited periodically, since references break and new trials change the picture. Evidence was last reviewed in August 2026.

Where AI fits, and where it does not

Analyses are compiled with AI assistance inside this pipeline: it reads and drafts, at a volume a person alone could not cover. What it does not do is decide the standard. The tier definitions and the grading rules are set by humans and applied the same way to every entry, and nothing is published until the reference checks pass. An AI-suggested citation that PubMed cannot confirm simply does not survive to the page.

Limits you should know about

A grade describes the state of published research, not what will happen to you. Trials report averages over groups; dose, formulation, duration and baseline health all move the result. "Limited" means the evidence is thin, not that a substance has been disproven — and "strong" says nothing about safety in your particular situation.

This is educational content, not medical advice. Talk to a doctor before starting a supplement, especially if you take medication or are pregnant. How the site pays for itself is set out in the affiliate disclosure, and the rest of the background is on the about page.