When a supplement brand says "third-party tested," the proof is supposed to be a Certificate of Analysis (CoA) -- the actual lab document. Most consumers never see one. When they do, the document is full of jargon and they have no idea what they are looking at. Here is how to read a CoA, what the signals are, and how to tell a real CoA from a marketing PDF dressed up to look like one.
What a real CoA always has
Every legitimate Certificate of Analysis carries these six pieces of information. If even one is missing, ask why.
- Identity -- the active ingredient name + a statement that lab-measured chemistry matches.
- Potency -- numeric measurement of the active ingredient (mg, IU, %), with the spec range and tolerance.
- Purity -- contaminant panel with results below stated thresholds. Common contaminants tested for: lead, arsenic, mercury, cadmium, residual solvents, microbial counts (yeast, mold, total aerobic bacteria), pesticide residues.
- Lab name + signatory -- which lab ran the test, with a signature or stamp from the analyst responsible.
- Batch / lot number -- the production run that was tested. This must match the lot number printed on your physical bottle to confirm the cert covers your specific batch.
- Date tested -- when the analysis was performed. Older than ~2 years and the cert is stale for current shelf product.
The signs of a fake / marketing CoA
Counterfeit and misleading CoAs are common in unregulated supplement aisles. The tells:
- No lab name -- the document just says "tested for purity" without naming the lab. Real CoAs name the lab.
- No batch number -- the document is product-level, not batch-level. Tells you nothing about the specific bottle you have.
- No numeric measurements -- everything is "pass / fail" without numbers. Real CoAs publish the measured values.
- No contaminant panel -- only identity and potency, no heavy metals or microbials. Common shortcut from low-rigor labs.
- Stamps but no signatory -- the document carries a lab logo but no analyst signature or initials. Reputable labs name the person who ran the test.
- "Independent" with no independence -- watch for in-house labs branded to look third-party. A real third-party lab is not owned by the brand or its parent company.
How to verify a CoA quickly
Three checks, in order:
- Lab name search -- type the lab's name into a search engine. Is it a real testing lab with a website, accreditation, and a record? Or does it only show up on the brand's marketing page?
- Batch number match -- does the lot number on the CoA match the lot number printed on your bottle? If not, the cert does not cover your batch.
- Recency -- is the test date within the last 2 years? Supplement shelf life is typically 2-3 years; certs older than that are stale.
The ScanCheck shortcut
Doing those three checks manually for every bottle is a lot of work. ScanCheck does the cross-reference automatically: point your camera at the label, we read the brand + batch number, then look up the matching CoA in our index of independent lab certificates. Green if your specific batch is on file. Amber if the brand is in our index but this batch is not. Red if no public independent lab cert exists for that brand. See the full lab list at /labs/ and the term glossary at /glossary/.