Health Literacy
Supplement label terms explained
Supplement labels use precise regulatory language that reads like marketing. Knowing what each term legally requires changes how you read the label.
Terms with real regulatory meaning
- %DV (% Daily Value) — the percentage of a standardized reference intake in one serving. Useful for comparison, though the reference values are general population targets, not individualized.
- USP Verified / NSF Certified — third-party testing marks confirming the product contains what the label claims, in the stated amount, without specific contaminants. These are the most meaningful quality signals on a supplement label, because supplements themselves aren't FDA-approved for efficacy before sale.[1]
- "This statement has not been evaluated by the FDA..." — required by law on structure/function claims (e.g., "supports immune health"). It signals the claim hasn't been independently verified, not that the product is necessarily ineffective.
The term worth watching closely
"Proprietary blend"
This lets a manufacturer list a combined weight for several ingredients without disclosing how much of each individual ingredient is included. A blend might contain a clinically studied dose of one ingredient and a token amount of another, and there's no way to tell from the label alone. Products that list each ingredient's exact individual amount are more transparent by definition.[1]
What "natural" and "clinically proven" don't guarantee
Neither term has a strict, enforced legal definition on supplement labels the way "USP Verified" does. "Natural" says nothing about dose, safety, or effectiveness — plenty of natural substances are potent or harmful in the wrong amount. "Clinically proven" can refer to a single small trial, not a robust evidence base.
Frequently asked questions
What does a 'proprietary blend' hide on a supplement label?
It lets a manufacturer list a combined weight for several ingredients without disclosing how much of each individual ingredient is included, making it impossible to know if a key ingredient is present in a meaningful dose.
What do USP Verified or NSF Certified marks mean?
They indicate third-party testing confirmed the product contains what the label claims in the stated amount, without specified contaminants — among the most meaningful quality signals available, since supplements aren't FDA-approved for efficacy before sale.
Does 'natural' mean a supplement is safe?
No. The term has no strict legal definition on supplement labels and says nothing about dose, safety, or effectiveness. Many natural substances are potent or harmful in the wrong amount.
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