Third party tested supplements: reading a four-part panel
Third party testing is not one test. It's a stack of four questions, and a single panel usually answers two. Identity asks whether the material in the jar is what the label says, including which species or form. Potency asks how much is there. Heavy metals and microbes are the safety half. A brand can say "third party tested" and mean someone ran a potency assay, a narrow claim.
Third party tested supplements live or die on four assays
Identity testing matters most in ingredients that arrive as powders from a long supply chain. Desiccated liver is a useful example because the material is a whole tissue, not a single purified molecule. Both beef liver and a cheaper substitute can pass a crude protein check while being different things. A certificate of analysis that names the assay method, such as microscopy paired with a species-specific test, is more informative than one that merely says the sample passed.
Potency is the second question. For a whole food ingredient, potency often means the naturally occurring vitamin and mineral content rather than a single active. USDA FoodData Central lists 3 oz of cooked beef liver at 83.1 mcg vitamin B12, 7,744 mcg RAE vitamin A, 3.4 mg riboflavin, 418 mg choline and 6.2 mg iron. Those are the reference values a manufacturer is trying to preserve through drying and blending, and the finished product label should sit somewhere sensible against them. Our grass fed liver gummies list desiccated liver supplying naturally occurring vitamin A, vitamin B12 and heme iron.
What a certificate actually shows
A certificate of analysis is a record for one batch tested on one date by one laboratory. It's not a permanent property of a brand. Batches change. Suppliers change. A certificate from 2023 says nothing about the jar in front of you today. If you're going to rely on testing at all, the useful question is which batch number was tested, by which lab, and for which of the four things above.
Microbial testing deserves a specific mention because it's the one most often skipped. Powders of animal origin carry a real load, and pasteurisation or irradiation decisions affect the result. Heavy metals testing is separate again, and it matters more for ingredients that concentrate minerals from soil, including liver and some plant extracts. Neither is covered by a potency assay.
Ask the brand directly
Send one message and see what comes back. Which batch, which laboratory, which four assays, and can you see the document. A brand that only runs potency will answer the first two questions and get vague on the rest, and that vagueness is your answer. Verification is voluntary in most of the market, so brands differ enormously in what they actually do.
One practical detail helps here. Batch numbers are usually printed near the best-by date rather than on the front label, and a certificate without a batch number is a brochure. Keep the photo of the code, because it's the only thing that ties a document to the jar in your kitchen.
My own habit is to check one product at a time rather than trying to audit a whole brand. I pick whatever I'm about to use daily, ask for the current batch certificate, and read the method column instead of the pass column. Ten minutes, once.
The four questions stay the same no matter what's in the jar.
Frequently asked questions
What does a certificate of analysis cover?Show answerHide answer
Only the assays that were ordered, which is why you should ask which of identity, potency, heavy metals and microbes were actually run.
Is third party testing legally required?Show answerHide answer
Verification is voluntary in most of the market, so what gets tested varies a great deal between brands and between batches.
What should I ask a brand?Show answerHide answer
Ask for the batch number, the laboratory name, the assays performed and a copy of the current certificate of analysis.
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.
