Our evidence hierarchy
- Systematic reviews and meta-analyses of high-quality studies — strongest weight.
- Regulatory actions and consensus statements from national or international health agencies.
- Well-designed independent testing (NSF, MADE SAFE, EWG, Consumer Reports).
- Individual peer-reviewed studies — weighted by design, sample size, and replication.
- Mechanistic evidence and animal studies — informative, but not decisive on their own.
- Expert opinion and brand claims — background only, never the basis for a recommendation.
How we handle disagreement
Where evidence conflicts — fluoride, seed oils, endocrine disruption at low doses — we describe the range of positions honestly and explain where mainstream regulators, independent researchers, and long-tail critics disagree.
We do not resolve genuine scientific disagreement by picking the side that makes for a cleaner recommendation.
When we change our view
New systematic reviews, regulatory updates, or independent testing can move us. When they do, the article is updated, the change is noted, and the updated date is refreshed. See our Corrections Policy for how.