A Certificate of Analysis — COA — is the single most useful document for judging supplement quality. Yet most shoppers have never seen one, let alone know how to read it. Here is a plain-English guide.
What a COA is
A COA is a laboratory report, ideally from an independent third-party lab, confirming what a specific production batch actually contains. It is batch-specific: a responsible brand issues a new COA for every batch, because every batch is a separate manufacturing run.
The key things to look for
- Batch or lot number — should match the number printed on your product. If it does not match, the COA is not for your product.
- Identity — confirmation that the substance is what it claims to be, often by a method such as HPLC or mass spectrometry.
- Purity / assay — the measured percentage of the active ingredient. For research-grade molecules, look for figures such as 99%+.
- Contaminant testing — screening for heavy metals, microbial contamination and, where relevant, solvents.
- The testing lab and date — an independent, named laboratory and a recent test date carry far more weight than an in-house, undated sheet.
Red flags
Be cautious if a brand cannot produce a COA at all, only offers one “on request” and then delays, provides a sheet with no batch number, or shows results from an unnamed lab. Transparency is the whole point.
How we do it
We publish a COA for every batch we sell in our COA Library — not on request, but openly. Match the batch number on your label to find yours.
This article is educational and reflects published research. It is not medical advice and does not describe the effects of any specific product. Food supplements are not a substitute for a varied, balanced diet and healthy lifestyle. Consult a healthcare professional before starting any supplement.
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