Third party tested supplements get checked on four separate questions: identity, potency, heavy metals and microbes. A batch of aged garlic extract can pass identity testing and still carry a lead reading nobody looked for, because a certificate of analysis only lists the assays someone paid to run. Ask which four areas were tested, on which batch, by which lab.
Identity: is the ingredient what it says
Identity testing confirms the material in the drum is aged garlic extract and not a cheaper allium powder, a question that costs a few dollars per sample and about 15 minutes of chromatography, priced in mg of marker per gram of extract. DNA barcoding and HPLC fingerprints both do this job. Without it, everything downstream is measuring the wrong thing precisely, which is worse than not measuring.
An aged garlic extract should show its marker compound, typically S-allyl cysteine, at a stated level in mg per gram of extract. If a panel quotes the marker, someone ran an assay. If it quotes only the blend weight, that number is a weighing, not a test.
Potency: how much is actually in there
Potency answers a different question. Identity says what it is, potency says how much of it, measured in mg per serving. Extracts degrade over shelf life, so a batch that tested at 1.2 mg of marker compound at release may test lower at month 14. Good makers test at release and at expiry and publish both.
The number to distrust is any potency figure with no batch number attached. It describes an average of the past, not the bottle in your hand.
Heavy metals and microbes: what testing doesn't cover
Garlic concentrates accumulate whatever the soil carried, so lead, cadmium and arsenic are the metals that matter here, with limits set in ppm, commonly below 10 ppm for lead in a finished product, alongside a 1,000 mcg ceiling some makers set for cadmium. Microbial testing covers the usual suspects, especially for anything processed at low heat. Both checks are separate orders, separate costs, and often skipped on domestic-market products.
This is the honest gap: verification is voluntary across most of the supplement market, and no law requires a brand to test for all four before selling. That's why two products with identical panels can sit at very different assurance levels, and why the price difference is sometimes just the cost of a lab bill.
What gets tested, in what order
A standard panel runs identity first, then potency, then contaminants, and a full pass on all four usually costs more than a single area check. Ask a lab-adjacent friend how much of this happens per batch and you'll get a range, but the sequence rarely changes.
Reading a certificate in two minutes
Picture the PDF in front of you. Header: batch number, matching the bottle. Lab name, with accreditation. Then a table of analytes with results and limits. What you want to check is narrow. Does the batch match. Does the method section list the four areas or only one. Are the metals results below their limits, not absent from the page.
A missing row is a not-tested, not a pass. That single reading habit separates a useful certificate from a marketing page.
The limits of certificates
A certificate describes 1 batch, 1 sample, 1 lab's run. It doesn't certify the next production lot or the product stored in a hot warehouse for a year. Treat it as evidence, not a guarantee, and weigh a brand's pattern across batches more heavily than any single clean sheet.
Concrete reference points help when you read one. A full panel takes about 15 minutes of chromatography per sample. Metals limits sit at 10 ppm or lower for lead in a well run certificate. Some brands add a 1,000 mcg ceiling for cadmium, and potency figures land in mg of marker per capsule rather than percentages of a blend.
Ask the four questions
Which batch was tested. Which lab. Which of the four areas. Where's the certificate. A brand that answers in a day has done the work; one that sends marketing copy hasn't.
That email takes ten minutes to write and settles most of the question.
Frequently asked questions
What does a certificate of analysis cover?Show answerHide answer
Whatever assays were ordered. Ask which were run before assuming anything.
Is testing legally required?Show answerHide answer
Verification is voluntary in most of the market, which is why brands differ so much.
What should I ask a brand?Show answerHide answer
Which batch was tested, by which lab, and for which four things.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
