How We Rate Evidence
Every herb profile on Herbal Teaory carries an evidence rating. Here's how we assign them and why it matters for your health decisions.
The Four Tiers
Supported by randomized controlled trials (RCTs), systematic reviews, or meta-analyses published in peer-reviewed journals. This is the highest standard of evidence in medicine. When we say "clinical evidence," we mean human studies with proper controls, not just test-tube or animal research.
What qualifies:
- At least one RCT with human subjects (n ≥ 30)
- Published in indexed, peer-reviewed journals
- Results replicated by independent research groups
- Systematic reviews or Cochrane analyses available
Herbs with Clinical Evidence:
Referenced in pharmacopoeia, authoritative medical texts, or supported by preliminary human studies that haven't yet reached the rigor of full RCTs. The evidence is promising but not conclusive.
What qualifies:
- Listed in official pharmacopoeia (European, Chinese, USP)
- Pilot human studies or observational studies
- Referenced in authoritative herbal medicine textbooks
- Strong mechanistic evidence from in-vitro and animal studies
Based on long-standing traditional medicine practices (TCM, Ayurveda, European herbalism) with documented historical use spanning centuries. Modern scientific validation is limited or absent, but generations of practitioners have observed benefits.
What qualifies:
- Documented use in traditional medicine systems for 100+ years
- Referenced in historical medical texts and materia medica
- No significant safety concerns from long-term traditional use
- Modern research may be underway but not yet conclusive
Early-stage research with promising but very limited results. May include only in-vitro studies, animal models, or single small human trials. We include these herbs because they have emerging scientific interest, but we're transparent about the evidence gaps.
Our Review Process
1. Literature Search
We search PubMed, Cochrane Library, and Google Scholar for peer-reviewed studies on each herb. We prioritize systematic reviews and RCTs, then work down to observational studies and case reports.
2. Source Verification
Every claim we make is linked to its source. When a DOI is available, we link directly to the published paper. We cite specific studies, not vague references to "research shows."
3. Tier Assignment
Based on the quality and quantity of available evidence, we assign a tier. This is clearly displayed on every herb profile page. We err on the side of caution — if the evidence is borderline, we assign the lower tier.
4. Regular Updates
Research evolves. We review and update our evidence ratings periodically as new studies are published. The "Updated" date on each profile reflects the last evidence review.
Important Caveats
We are not medical professionals. Herbal Teaory provides educational content based on published research. Our evidence ratings reflect the state of scientific literature, not medical recommendations.
Evidence ≠ efficacy for you. A Tier 1 rating means the herb has strong research support, not that it will work for every individual. Biology is complex, and individual responses vary.
Always consult your healthcare provider before using herbal teas therapeutically, especially if you take medications, are pregnant, or have chronic conditions.