How We Research, Grade Evidence & Source
Our methodology prioritizes original studies, systematic reviews, and regulatory guidance. We consider study design, relevance, consistency, funding, and disclosed conflicts so readers can see the basis and limitations of each grade.
The evidence ladder
Not all evidence carries equal weight. We rank study types from strongest to weakest, and a claim's grade reflects the best available evidence supporting it.
How we review funding and conflicts of interest
We review the funding and conflict information available in study reports, trial registrations, institutional profiles, patent records, and other relevant disclosures. When a relationship cannot be verified, we label it unclear rather than assuming independence.
Funding and conflicts are considered alongside study design, relevance, consistency, and replication; they do not by themselves determine a conclusion.
For each claim-bearing study, the intended record is: declared funder, relevant author affiliations, declared conflicts, product supply, and any other relationship that is directly documented. Missing information is recorded as not reported or unclear.
Research databases and source types we use
Every source below is grouped by type. We link to the original wherever possible — and note where a source is used only for discovery or context.
Peer-reviewed literature
Research databases
A principal database for locating and verifying biomedical research. We link to PubMed records where they are available and relevant.
Independent systematic reviews, considered the gold standard for evidence synthesis.
Used for discovery only; we trace back to the primary source before citing.
Discovery only
Independent & government health
Balanced reference
Fact sheets with balanced, referenced summaries.
National Center for Complementary and Integrative Health — evidence on supplements and botanicals.
Global guidance and monographs.
Used for context only, not as primary evidence.
Context only
Regulatory & toxicology
Safety & status
Regulatory status, GRAS designations, adverse event reports.
Herbal monographs and assessment reports.
- EFSA↗
European Food Safety Authority — safety opinions and tolerable upper intake levels.
Regulatory status and limits from India's food safety authority.
Third-party quality and contaminant testing.
Partly paywalled
Systematic review bodies
Evidence synthesis
Independent, non-profit systematic reviews.
Evidence synthesis in health.
Comprehensive, but partly commercial; a starting point, not a final source.
Starting point
Adverse events & interactions
Safety signals
Drug-induced liver injury, including supplement-related.
Patient-facing drug and supplement information, including interactions.
Cross-referenced with primary sources.
Nutrition databases
Composition & intake
Nutrient composition data.
Recommended intake and upper limits.
What we avoid
Some sources look authoritative but carry a built-in bias or add nothing verifiable. We do not treat any of the following as evidence.
- Press releases — written to promote a finding, not to weigh it, and often out of step with the underlying data.
- Affiliate sites — pages that earn commission on the products they recommend have a financial reason to overstate benefits.
- Marketing materials — brand claims, sponsored content, and product copy are advertising, not evidence.
- Aggregator blogs — sites that restate other articles without checking the primary source, compounding any original errors.
Source rule: Verdict-bearing claims should be supported by original research, evidence syntheses, or regulatory sources. Contextual sources may help explain a topic, but should not determine the evidence grade.
Limitations of our approach
No review can guarantee that it has captured every study. We prioritize relevant evidence syntheses and higher-quality human research, while documenting important limitations. Evidence evolves; each article should show a responsible review date and substantive updates should include a dated change note.
Methodology version: July 2026.
For verdict-bearing claims, the intended process combines study design, relevance, consistency, funding, and disclosed conflicts. The article should make the grade, supporting sources, and material limitations traceable to readers.
See how grades are applied to ingredients · See our full source list
This page documents the current methods framework and should be versioned when it changes.