"Third-party tested" appears on a lot of supplement labels these days. But tested for what? By whom? To what standard? And can you see the actual results?
A Certificate of Analysis (COA) is the document that answers all of those questions. It's the single most important piece of transparency a supplement brand can offer, and most brands either don't have one, or have one and won't share it.
Here's how to read a COA and what to look for.
What Is a Certificate of Analysis?
A COA is a formal report issued by a testing laboratory that documents the results of quality and safety testing on a specific batch of a product. It's not a certification; it's data. Each COA is specific to a single production batch (identified by a lot number), so it reflects the actual product that was manufactured and sold, not a one-time test years ago.
A COA tells you: what was tested, what methods were used, what the results were, and whether they passed or failed established standards.
Who Issues a COA?
COAs can be issued by an in-house lab (internal testing) or an independent third-party lab (external testing). Only third-party COAs are meaningful from a consumer trust standpoint; a brand testing its own products has an obvious conflict of interest. Any brand worth trusting uses an independent lab that has no financial stake in whether the product passes or fails.
The most credible third-party labs are accredited to ISO/IEC 17025:2017 -an international standard for testing laboratory competence. Look for this accreditation on any COA you're reviewing.
The Three Things a Supplement COA Should Test
1. Potency (Does it contain what the label says?)
Potency testing confirms that the stated active ingredients are present at the claimed levels. This is critical. A 2015 FDA survey found that many dietary supplements contained significantly less of their active ingredient than the label claimed, sometimes none at all. A potency COA shows you the actual measured amount per serving.
What to look for: the test result should be close to (and ideally at or slightly above) the label claim. A result significantly below the label claim is a red flag.
2. Heavy Metals (Is it safe?)
Heavy metal testing checks for arsenic, cadmium, lead, and mercury, the four metals of primary concern for human health, regulated under USP standards (the United States Pharmacopeia). These metals can appear in supplements as contaminants from raw materials, soil, or manufacturing equipment.
What to look for: all four metals should show "PASS" or results listed as "below LOQ" (below the limit of quantification, meaning the instruments couldn't detect any). A single "FAIL" should disqualify the product entirely.
3. Microbiological Safety (Is it free of pathogens?)
Microbiological testing checks for harmful bacteria and fungi: E. coli, Salmonella, Staphylococcus aureus, total aerobic plate count, coliform count, yeast, and mold. These can enter supplements through raw ingredients, manufacturing environments, or improper handling.
What to look for: Salmonella and E. coli should be "Not Detected." Other categories should be within USP limits.
Why Most Brands Don't Share Their COAs
There are a few reasons a brand might not publish or share COAs:
- They haven't done third-party testing - which is more common than you'd think, as dietary supplement testing is not federally mandated for every batch
- They've done testing, but the results weren't flattering
- They tested once (during product development), but not every batch
- Their manufacturer has COAs, but the brand never asked to see them
A brand that has clean COA results and tests every batch has every reason to share them. The absence of a COA, or a brand that says "testing is done" without providing the actual document, is a meaningful signal.
Vitamin Hive's Testing
Every production batch of Vitamin Hive D3+K2 gummies is sent to a third-party laboratory - accredited to ISO/IEC 17025:2017. We test potency (both D3 and K2), heavy metals (all four, USP <233> standard), and microbiological safety (USP <2021> and <2022> standards). Our current batch COA results: all pass, all heavy metals below LOQ, D3 confirmed at 69.30 mcg/serving, K2 at 109.84 mcg/serving.
We share our COA on request - just contact us, and we'll send it. No runaround, no marketing fluff. Just the actual results.