Understanding third-party testing and certificates of analysis

Third-party testing means an independent laboratory, with no commercial stake in the result, analyses a finished batch.

What it can verify: identity (the ingredient is what the label says), potency (the amount matches the label), and purity (heavy metals, microbes, solvent residues and, for fish oils, oxidation markers are below defined limits).

What it does not verify: that the product works, that the dose is right for your child, or that the claim on the front of the box is supported by evidence.

Certificates of analysis (COA). A COA is the document behind the claim. A meaningful COA names the laboratory, the batch or lot number, the test methods and the specification limits. If a brand will not supply one on request, treat the "lab tested" claim as unverified.

Certification programmes. Programmes such as pharmacopoeial verification or sports-testing schemes add an audited layer on top of batch testing. They are a strong signal, but their absence is not proof of a poor product — many small European brands test rigorously without paying for a certification mark.