How We Research, Grade Evidence & Source
Our methodology is independent and built on primary sources. We start with the original studies, weight them by quality and independence, and trace the money and relationships behind the research — so every grade reflects the evidence itself, not who is promoting it.
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 trace funding and conflicts of interest
A study's declared conflicts are only the starting point. We go beyond author self-disclosures to independently verify who paid for the research and who stands to gain from its findings.
Author declarations are frequently incomplete or absent. Rather than take them at face value, we independently investigate the relationships around each study — and weight the evidence accordingly.
Primary databases 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
Primary databases
The backbone of our medical research. Every study cited links to its PubMed entry where possible.
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.
The rule of thumb: if a claim cannot be traced back to a primary study, a systematic review, or a regulator, it does not shape our verdicts.
Limitations of our approach
- We cannot read every study ever published; we prioritize systematic reviews and recent high-quality RCTs.
- Evidence evolves. We date every article and revisit claims as new research emerges.
This methodology is itself reviewed and updated periodically. Last reviewed: July 2026.
For every claim we grade, we combine the evidence ladder with our funding and conflict checks. A finding built on strong, independent research earns a high grade; one resting on weak or industry-tied evidence is graded down and flagged. The result is a verdict you can trace — from the grade, to the studies, to who paid for them.
See how grades are applied to ingredients · See our full source list
Our methods are reviewed and updated as evidence standards evolve.