Independent supplement ratingsUS and Canada · Updated weekly
A ratings desk for a category that has spent thirty years grading its own homework.
A ratings desk for a category that has spent thirty years grading its own homework.
NSF, Informed Sport, USP: what the seals mean, what they don't, and when to care.
A third-party seal answers one narrow question: is what is in the tub what the label says, and is there anything in there that should not be? It does not answer whether the product works. Those are two different problems, and the seals only solve the first one.
Because nobody inspects a supplement before it is sold. Manufacturing standards exist, but verification that a specific product matches its specific label is voluntary — a brand pays for it, or it does not. For a magnesium powder, that risk is mild. For anything an athlete takes, or anything in a category with a history of undeclared pharmaceutical ingredients, it is the whole ballgame.
The strictest of the common seals, and the one aimed at drug-tested athletes. Certification involves screening for around 290 substances banned by major sporting bodies, confirming that label contents match what is in the product, a formulation and label review, inspection of the manufacturing facility and its suppliers, and ongoing monitoring. It is the programme recognised by USADA, MLB, the NHL and the CFL. (NSF, Certified for Sport)
What it buys you: high confidence that the tub is clean and that the label is honest about contents.
Both are run by LGC and use the same accredited testing methods. The difference is frequency, and it is not a small one.
Informed Sport tests every batch before it is released for sale, plus additional blind samples bought at retail afterwards. Informed Choice works by monthly blind sampling — the lab buys the product off the shelf and tests it, at least twelve batches a year at random. Same methods, but with Informed Choice there is no guarantee that the specific tub in your hand came from a tested batch. (Informed Sport vs Informed Choice, LGC)
If you are drug-tested, that distinction is the entire point. If you are not, either is a reasonable signal that a brand takes contamination seriously.
The United States Pharmacopeia mark focuses less on sport and more on pharmacy-grade fundamentals: that the ingredients and amounts match the label, that the product does not contain harmful levels of specified contaminants, that it breaks down and releases its contents in the body, and that it was made under good manufacturing practices. (USP, the Verified Mark)
Fewer supplements carry it than you would expect, and its absence on a mainstream vitamin is not damning. Its presence is a genuine plus.
This is the part every "trusted brands" roundup skips. A certified product can be perfectly clean, perfectly labelled — and dosed at a fifth of what the research used. Certification verifies the label; it never asks whether the number on the label is worth anything.
You can be NSF Certified for Sport and useless. Plenty of products are. That is exactly the gap our scoring exists to close: testing seals are one input, and the dose against the research is a heavier one.
And verify the seal rather than trusting the picture: NSF, Informed Sport and USP all publish searchable lists of certified products. A logo printed on a box is a JPEG. A listing in the register is a fact.
Written and fact-checked by the NFS editorial team · Educational only — not medical advice.