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How to Compare Health Claims Without Confusing a Study With a Sales Promise

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The Short Answer

A study finding, a guideline recommendation, a label statement, and a seller statement are four different kinds of claim. Before you trust one, decide which kind it is. Then ask who made it, who it covers, what was measured, and what is still unknown. The FDA says it generally does not approve dietary supplement claims or labeling before use, so a claim on a label or in an ad is not the same thing as a study result. To see the same framework applied to a specific marketed product without treating the seller claim as proof, read our NeuroSalt review.

By MedicalFoundationOfNC.org Research Team. MedicalFoundationOfNC.org is an independent editorial publication. It is not affiliated with The Medical Foundation of North Carolina, Inc., UNC Health Foundation, or the University of North Carolina, and it is not a medical practice. Educational information only, not medical advice.

Study Finding

  • Who made it: Researchers, often with a sponsor. The NIH describes sponsors as people, institutions, companies, or agencies that start, manage, or finance a trial without conducting it. Ask who funded the study.
  • Who it covers: People who met the trial’s inclusion and exclusion criteria, which the NIH says are based on factors such as age, gender, type and stage of disease, treatment history, and other medical conditions. A result may not carry over to someone who would not have qualified.
  • What was measured: The NIH says clinical trials evaluate an intervention’s effects on health outcomes. Check that the outcome measured matches the outcome the claim promises.
  • What remains unknown: Sample size, study date, and whether other teams found the same thing. NCCIH says small studies are more likely to produce results due to chance, that the strongest evidence comes from several studies by different investigators, and that the date helps show how a study fits the larger body of evidence.

Guideline Recommendation

  • Who made it: Ask which organization issued it and when.
  • Who it covers: Ask whether it addresses your situation, or only a related one.
  • What was measured: Ask which outcomes the recommendation says it is aiming at.
  • What remains unknown: Ask what evidence the guideline says it rests on.

Our guide How to Grade Health Evidence covers guidelines and study design in more depth.

Label Statement

  • Who made it: The manufacturer, packer, or distributor named on the label.
  • Who it covers: Check whether any studied population is named at all.
  • What was measured: The Supplement Facts panel lists the serving size and each dietary ingredient, with the amount per serving except for ingredients in a proprietary blend. A structure/function claim describes an effect on the body’s structure or function. The FDA says the disclaimer “This statement has not been evaluated by the Food and Drug Administration” is required with such claims because they are not FDA-approved. A product sold as a supplement but represented as treating, preventing, or curing a specific disease is regulated as a drug.
  • What remains unknown: Whether any study tested this exact product and dose. The FDA says it does not test dietary supplements before they are sold.

Seller Statement

  • Who made it: The company or advertiser. The FDA says the FTC generally oversees supplement advertising, while the FDA generally handles safety, quality, and labeling.
  • Who it covers: Check whether the ad says who it applies to.
  • What was measured: Check whether a study is named, and what outcome it measured.
  • What remains unknown: Everything, until you find the underlying research. The FDA suggests contacting the manufacturer, whose name and address are on the label, for more detail than the label gives. NCCIH suggests asking who runs and pays for a website and whether its claims seem too good to be true.

Illustration (invented for teaching, not a real product): an ad says a product is “backed by science.” That is a seller statement. If no study is named, the population, outcome, and limits are all unknown, and the claim stays unverified until you locate the research yourself.

Who Should Ask a Professional First

The FDA advises talking with a doctor, pharmacist, or other health care professional before deciding to use a dietary supplement, in part because some supplements might interact with medicines or other supplements. Do not change or stop prescribed treatment based on a web article, including this one.

What You Can Do Next

  1. Pick one claim you have seen recently and label it as one of the four kinds.
  2. Answer the four questions for it. “Unknown” is a useful answer.
  3. Look for the original study, not a summary. The NIH says published results can be found in PubMed by searching the study’s official name or protocol ID.
  4. Bring your notes to a pharmacist or clinician.
  5. See How We Review and Our Standards and Disclosures for how this site handles sources. Use the Contact page to report an error.

See also the About page and the full Medical Disclaimer.

Sources

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