Can you trust a supplement label?

Before buying a supplement, check the certifier's product and batch records: testing cannot guarantee health benefits or zero risk.

Ingredient identity, quantity, contaminants and banned substances are different testing questions. Do not assume that every program covers all of them, or that a brand-level statement certifies every product it sells.

What have tests of sports supplements found?

Cohen and colleagues (2023, PMID 37459101) analyzed 57 products labeled with one of five botanical ingredients marketed for performance-related uses. In 23 products, the labeled ingredient was not detected. Only six contained a quantity within 10% of the stated amount.

This is direct evidence of labeling problems in that selected product sample. It is not a finding that 89% of all supplements are mislabeled, or evidence about an untested brand. Products were selected for specific ingredients, so the results cannot represent every protein powder, creatine product or multivitamin.

For label accuracy, a laboratory analysis of retail products answers the question more directly than a human efficacy trial. It still cannot establish whether taking those products improves training or causes a particular health outcome.

Read the sampling limits

The researchers purchased products online in 2021 and tested one sample from each product. They selected products listing Rauwolfia vomitoria, methylliberine, turkesterone, halostachine or octopamine. Results do not establish consistency across other batches, or the contents of products currently for sale. The paper's Methods, Results and table report the analyses; its Discussion describes these limitations.

Does the FDA approve a supplement before it reaches a store?

The FDA's supplement questions and answers explains that it does not approve supplements for safety and effectiveness before marketing. Manufacturers and distributors are responsible for meeting applicable safety and labeling requirements.

That does not mean supplements are exempt from regulation. It means a product's presence on a retail shelf is not FDA approval of its contents or advertised results. Independent certification is a separate check, and its scope needs to be read carefully.

What do certification programs actually cover?

NSF Certified for Sport describes label-content checks, contaminant and banned-substance testing, facility review and ongoing monitoring. Its product directory lets you check a listed product and tested lots.

Informed Sport describes testing every certified product batch for banned substances before sale. Its directory allows searches by product, brand or batch. That banned-substance focus should not be interpreted as a blanket verification of every ingredient dose or of clinical effectiveness.

A claim such as “lab tested” needs supporting detail: which laboratory, which finished product or batch, which substances, and which limits? Even a valid result applies to the tests performed. No seal establishes that a supplement is right for every person or guarantees that an athlete cannot fail a drug test.

How do you check the product you are holding?

1. Open the certifier's own directory using the links above.
2. Match the product name and formulation, not just the brand logo.
3. Match the lot or batch when the program provides batch records.
4. Read the program's coverage. For a laboratory report, check the product identifier, date, tests and results.
5. If details do not match, ask the certifier or manufacturer before relying on the claim.

Our foundation-first guide can help you decide whether there is a useful reason to buy a supplement at all. Browse the supplement collection separately; this article does not certify those products or claim every item has independent batch verification.

FAQ

Does certification mean a supplement works?

No. Testing contents and studying benefits are different tasks. Certification does not establish that an ingredient or dose improves your training outcome.

Does no public Certificate of Analysis prove contamination?

No. Missing documentation leaves the claim unverified; it is not a laboratory finding. You can ask for matching records or choose a product with more readily verifiable information.

Is a brand listed in a directory enough?

Check the exact product and formulation, then the batch where applicable. A listing for one product should not be applied to the brand's entire range.

Can third-party testing eliminate every risk?

No. Testing has a defined scope and detection limits. Personal health, medication interactions and sport-specific requirements still matter; a pharmacist, clinician or sports governing body can help with those questions.