Walk through any supplement brand's website and you'll find the phrase almost everywhere. Ultra-pure creatine. Pharmaceutical-grade. The purest form available. Sometimes there's a certificate-shaped icon next to it. Sometimes it says "lab tested." Almost never does it say tested for what, by whom, or what the actual result was.

This is worth slowing down on, because "pure" sounds like a specific, verifiable claim. In chemistry it has a precise meaning: how much of a substance is actually the substance you paid for, measured as a percentage. When a brand prints "ultra-pure" on a label, you get a word that sounds like proof, with no actual proof behind it.

A creatine powder can be called ultra-pure by anyone. It costs nothing to print. What would actually back up that claim is a document from a lab, one that physically tested the powder and reported what it found with numbers.

What those numbers actually measure is whether the powder is mostly what it says it is, and whether the manufacturing process left anything behind that shouldn't be there. Some raw materials carry trace amounts of heavy metals, for example. A proper test checks for those things and reports the actual result, a number, next to a limit that says what's acceptable and what isn't. When those results are published for the specific bag you're buying, you can look at them yourself and see whether the powder passed.

When a brand publishes that document, tied to a specific batch, you have something to inspect. When it doesn't, "ultra-pure" is doing all the work on its own.

The next time you're evaluating any creatine product, the question worth asking isn't whether the label says tested, but rather if you can see the result, if that result is tied to the batch being sold right now.

If the answer to those is yes, you have something real to look at, but if the answer is "trust us," you got yourself a marketing phrase.