In the US, dietary supplements are not approved by the Food and Drug Administration before they go on sale. Brands are responsible for making sure their products are safe and labeled accurately, and the FDA can act after a product is on the market. That gap is why third-party testing matters to many shoppers, and why our supplement tables have a column for it.
This guide explains what third-party testing usually means, how a few well-known programs work in general terms, and how to check a claim yourself. It is general information. It does not mean any certified product is right for you. Talk to your doctor or pharmacist before starting a supplement.
These statements have not been evaluated by the Food and Drug Administration. Supplements are not intended to diagnose, treat, cure, or prevent any disease.
"Tested" is not one thing
Supplement packaging and websites use testing language loosely. Very different things can sit behind the same word:
- In-house testing: the brand or its manufacturer tests its own products
- Third-party lab testing: the brand pays an independent lab to test a batch, and may publish the results (often called a Certificate of Analysis or COA)
- Third-party certification: an independent organization runs an ongoing program with its own standards, testing and audits, and lists products that pass in a public directory
All three can be useful. They are not equal, and a page that simply says "third-party tested" doesn't tell you which one you are looking at.
What certification programs generally look at
Certification programs differ, so always read the certifier's own description. In general terms, programs aimed at supplements may check some combination of:
- Whether the product contains what the label says, in the amounts listed
- Whether it contains certain contaminants above set limits, such as specific heavy metals or microbes
- For sport-focused programs, screening for substances banned in sport
- Whether the facility follows good manufacturing practices, often through audits
- Ongoing retesting, rather than a single check at launch
Certification is about the product and the process. It is not a judgment that the product will do anything for your body.
NSF Certified for Sport
NSF is an independent public health and safety organization that runs several certification programs. NSF Certified for Sport is its program aimed at athletes and sports organizations. NSF describes it as testing that products contain what the label says and screening for a long list of substances banned by major athletic organizations, along with facility audits and ongoing testing.
NSF publishes a searchable public directory of certified products. That directory is how we confirm a certification before we show it in our tables: if a product appears in NSF's own listing on the date we check, our table says "NSF Certified for Sport (listed on nsfsport.com)". If we can't find it, we show "See site", even if the brand's page uses the mark.
Informed Sport and Informed Choice
Informed Sport and Informed Choice are certification programs run by LGC, a science and testing group. They screen products for substances prohibited in sport. Informed Sport is batch-focused, so certified batches can be looked up. Like NSF, they publish public search tools.
Brand-published batch results
Some brands don't hold a formal certification but publish the results of independent lab tests for each batch, often listing heavy metals, microbes and allergens with the lab's limits. This is more transparent than saying "tested" with nothing to back it up, and you can often match the results to the lot number on your container.
It is still different from certification. The brand chooses the lab, the tests and what to publish. In our tables we label these products as "batch tested by third-party labs; results published by the brand" so they are never confused with a certification program.
How to check a certification yourself
It takes about two minutes:
- Note the exact product name, size, flavor and lot number from the container
- Go to the certifier's own website, not a link from the brand's page
- Search the certifier's directory for the brand and product
- Check that the specific product (and flavor, where listed) appears
- For batch-based programs, check the lot number too
If a product isn't in the directory, ask the brand. Certifications can lapse, and some products in a brand's range may be certified while others are not. In our own checks, a brand's whole website sometimes shows a certification badge, but the certifier's listing is what tells you which products are actually covered.
What certification does not tell you
Even a certified product:
- May not suit your health, medications or diet
- May not do what the front of the pack suggests
- May still contain allergens such as milk, fish or soy
- Can be a poor value per serving compared with alternatives
Certification answers the question "is this what it says it is, made under checked conditions?" It doesn't answer "should I take this?" That question belongs with your doctor or pharmacist.
Other public records worth knowing about
Beyond certification, a few public sources can tell you about a brand's history:
- The FDA's warning letters database and its recalls listings
- The Federal Trade Commission's cases and warning letters, which cover advertising claims
- Court records for class actions about labeling or contamination
- The Better Business Bureau profile and complaint history
- Patterns in customer reviews about billing, cancellation and service
Still Stride uses these sources when deciding which supplement brands to list at all. We describe that screen on our supplements page.
Questions to ask a brand
If a product page mentions testing but you can't find details, it is reasonable to email the brand and ask:
- Which organization certifies the product, and under which program?
- Is every flavor and size covered, or only some?
- Can you see the test results for the lot number on your container?
- How often are products retested?
A brand that tests seriously will usually be glad to answer.
How Still Stride shows testing
In every supplement comparison table, the "Third-party testing" column shows one of:
- NSF Certified for Sport (listed on nsfsport.com): we found the product in NSF's public directory on the date shown
- Batch tested by third-party labs, results published by the brand: the brand publishes independent lab results, but isn't certified by a program
- See site: we couldn't confirm a certification for that product
We never upgrade a brand's claim beyond what we can confirm, and we recheck when we update a page.
About this guide
Our supplement guides explain labels, testing programs and terms so you can ask better questions. We don’t make disease or treatment claims, we haven’t hands-on tested products, and we don’t publish invented statistics or ratings. Product facts come from official brand pages and certifier listings. How we work.