How to read a grade
Also in the library: Ingredients · Goals · Evidence
Livestack grades each ingredient–goal pairing, not the ingredient in the abstract. Creatine can be grade A for strength and grade B for focus. The letter is a reading of the human evidence we store for that pairing — how much ink the literature has earned — not a score for a bottle, a brand, or a person.
The scale is the same one on every chip on the site.
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More than one randomized trial in people, or a meta-analysis of those trials, pointing the same way.
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A real human trial base, but narrower or less replicated than A.
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People were studied, but the design is weaker or the samples are small. A C pairing can still appear in a stack when the rest of the situation allows it; we will say the evidence is thin.
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No adequate human efficacy record. Grade D never appears in a recommendation.
What a grade is not
A grade is not medical advice, a diagnosis, or a reason to start or stop a supplement. It does not rate product quality, purity, or a merchant. It does not mean the pairing is appropriate for you — medications, conditions, and dose still decide that, and those questions belong with your doctor or pharmacist.
The records behind each grade are public. Start from the evidence index, or from an ingredient monograph.