Evidence Grading System
Zynava uses a transparent grading system to communicate the strength and quality of available research for each ingredient. Our goal is to help you understand what the science says — and what it doesn't.
How We Grade Evidence
Each evidence grade reflects the volume, consistency, and quality of peer-reviewed research from sources including PubMed, NIH, and PubMed Central (PMC). Grades are not endorsements — they describe the current state of the evidence.
Grade A — Strong Evidence
Multiple well-designed clinical trials, systematic reviews, or meta-analyses support a consistent finding. Results have been replicated across different populations and study designs.
Grade B — Moderate Evidence
Several clinical studies show positive results, but the evidence may be limited by smaller sample sizes, fewer replications, or some inconsistency between studies.
Grade C — Preliminary Evidence
Early-stage research (animal studies, in-vitro studies, or small pilot trials) suggests potential benefits, but human clinical trials are limited or results are mixed.
Grade D — Insufficient Evidence
Very limited or no peer-reviewed research is available. Claims are largely based on traditional use, anecdotal reports, or theoretical mechanisms that have not been tested in rigorous studies.
Important Limitations
- Evidence grades reflect the current state of research and may change as new studies are published.
- A high evidence grade does not mean a supplement is right for you. Individual factors like medications, health conditions, and genetics all matter.
- These grades are not medical recommendations. Always consult with a qualified healthcare provider before starting any supplement.
- Zynava does not conduct original research. We reference publicly available studies from established databases.
Our Sources
All referenced studies come from trusted, peer-reviewed databases:
- PubMed — U.S. National Library of Medicine
- PMC — PubMed Central full-text archive
- NIH — National Institutes of Health
Disclaimer: Zynava provides educational information only. Evidence grades are not medical advice, diagnoses, or treatment recommendations. Consult a healthcare professional before using supplements. See our full Medical Disclaimer and Editorial Policy.
Last Updated: February 2026