Structure/function claims vs disease claims on supplement labels

A structure/function claim says a supplement affects how the body normally works, such as "supports joint comfort." A disease claim says it diagnoses, treats, cures, or prevents a disease, and under US law only a drug can say that. The disclaimer you see on most supplement labels exists because of that line.

The line matters when you read a sales page, because many pages walk right up to it. Below is how the FDA describes each type of claim, what the rules say makes a statement a disease claim, and a short checklist you can use before you buy. Every rule quoted here comes from government pages we opened while writing, listed at the end.

What is a structure/function claim?

The FDA defines it in plain terms. Structure/function claims may describe the role of a nutrient or dietary ingredient intended to affect the normal structure or function of the human body. The agency's own example is "calcium builds strong bones." They may also describe the way an ingredient acts to maintain that structure or function, for example "fiber maintains bowel regularity" or "antioxidants maintain cell integrity."

These claims became a standard feature of supplement labeling after the Dietary Supplement Health and Education Act of 1994, usually called DSHEA. That law set up special rules for them, and for two related types: claims of general well-being, and claims about a nutrient deficiency disease (like vitamin C and scurvy), which are allowed only if the label also says how common that disease is in the United States.

Notice what all of these have in common. They talk about normal, healthy function. "Supports," "maintains," and "promotes" are the typical verbs. None of them names an illness.

What makes a statement a disease claim?

The FDA's regulation on this topic (21 CFR 101.93) defines a disease as damage to an organ, part, structure, or system of the body such that it does not function properly (its example is cardiovascular disease), or a state of health leading to that kind of dysfunction (its example is hypertension). Diseases that result from essential nutrient deficiencies, like scurvy, are carved out of that definition.

The regulation then lists criteria the FDA uses to decide whether a statement claims to diagnose, mitigate, treat, cure, or prevent a disease. A statement counts if it claims, explicitly or implicitly, that the product:

• has an effect on a specific disease or class of diseases;
• has an effect on the characteristic signs or symptoms of a specific disease, in scientific or everyday words;
• is a substitute for a therapy for a disease, or augments a drug that is meant to treat one;
• has a role in the body's response to a disease;
• treats or prevents side effects of a therapy, when those side effects are themselves diseases.

The regulation also says a disease claim can be implied through things other than a sentence: the name of the product, a statement about its formulation, the use of the word "disease," or "pictures, vignettes, symbols, or other means." It even covers citing a publication, if the citation refers to a disease use and, in the context of the labeling as a whole, implies treatment or prevention, for example through inappropriate prominence or a lack of relationship to the product's stated claims.

What does the disclaimer actually mean?

If a label carries a structure/function claim, it must also carry a disclaimer. The text reads: "This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease." The FDA explains that the second sentence is there because only a drug can legally make a disease claim.

Read that as two separate messages. The first sentence tells you the FDA did not review the claim before it was used. The second tells you the product is being sold as a supplement, not as a medicine. Neither one says the claim is true or false. They only tell you what kind of claim it is and that nobody at the agency checked it first.

The company still has a duty. The FDA says the manufacturer must have substantiation that a structure/function claim is truthful and not misleading, and must send the FDA a notification with the text of the claim no later than 30 days after it starts marketing the product with that claim. The FDA does not pre-approve the wording. If you want the wider picture of what the agency does and does not sign off on, the blog has a separate article on what "FDA approved" means for a supplement.

What about health claims?

There is a third category that people mix up with the other two. A health claim describes a relationship between a substance in the supplement and a reduced risk of a disease or health-related condition. The National Center for Complementary and Integrative Health gives an example: "Calcium may reduce the risk of the bone disease osteoporosis" is a health claim, while "Calcium builds strong bones" is a structure/function claim.

The FDA says different requirements apply to each claim type, and NCCIH says health claims must be based on scientific evidence. The practical takeaway is simple: a sentence that names a disease and says "reduce the risk" is not the same kind of claim as one that says "supports," even when both sit under the same brand name.

Who checks these claims once they are made?

Two agencies share the job. The FDA reviews product labels and other labeling information, including websites, to check that products do not include claims that could make them drugs, such as claims to treat, diagnose, cure, or prevent diseases. It does this after the product is already on the market, since it does not approve supplements first.

The Federal Trade Commission covers advertising. Its guidance says that advertising must be truthful and not misleading, and that advertisers must have adequate substantiation for all objective product claims before they run an ad. For health benefits or safety claims about foods, supplements, and drugs, the general rule is substantiation in the form of competent and reliable scientific evidence. The FTC also notes that it has no parallel notification requirement like the FDA's 30-day notice, but both agencies expect the marketer to have the proof in hand before making the claim.

So a supplement page can be inside the FDA's structure/function rules and still be misleading under advertising law, for instance by presenting an ingredient study as if it tested the finished product. That gap is exactly where we spend most of our time when we review an offer. Our review method explains how we compare each claim with what the label and the research support.

How do these rules show up on real sales pages?

We do not decide what is legal; that is the FDA's and FTC's job. What we can do is show how the vocabulary above appears in the reviews on this site, using what those reviews already say.

Take a claim that looks safely on the structure/function side. Our ProDentim review quotes a page that says its three ingredients are "clinically proven to support the health of your teeth and gums." The review's finding is about the evidence, not the legal category: the one controlled trial the page links tested a different probiotic strain than the one in the product.

Now take a case where the page cites research about a named condition. Our Kerassentials review notes that the page cites real papers on toenail fungus, including a tea tree oil trial, but that none of them tests the bottle, and the trial we opened used pure tea tree oil rather than a mixed blend. Whether the way those citations are presented crosses the FDA's line is not for us to say. What a reader can check is whether the study matches the product.

A third pattern is a page that invents or renames a condition to sell against. The Gluco6 review flags an invented condition name ("GLUT-4 Overwhelm") that we could not find defined in the research literature. Blood sugar products in general make up a crowded corner of the market; you can browse how they compare in the blood sugar category.

A checklist for reading a supplement claim

1. Look for the verb. "Supports," "maintains," and "promotes" describe normal function. "Treats," "reverses," "fights," and "eliminates" describe disease outcomes.
2. Look for a named illness. If the page names a condition, ask whether the product is being sold as a supplement or implied to act like a medicine.
3. Check the whole page, not just the label. The FDA's criteria include product names, pictures, vignettes, and citations placed to suggest a disease use.
4. Find the disclaimer. Its presence tells you the claim was not reviewed by the FDA. It does not tell you whether the claim is supported.
5. Match the study to the product. Note the ingredient, the dose, and the population in any cited trial, and compare them with the label.
6. Ask a professional. If you have a health condition or take medication, talk to a doctor or pharmacist before starting a supplement.

FAQ

Can a supplement legally say it treats a disease?

No. The FDA says only a drug can legally make a claim to diagnose, treat, cure, or prevent a disease. A product sold as a supplement that is represented as a treatment for a specific disease can be regulated as an unapproved drug.

Does the "not evaluated by the FDA" line mean the product is unsafe?

Not by itself. The sentence is a legal disclaimer about the claim next to it. It says the FDA did not evaluate that statement and that the product is not intended to diagnose, treat, cure, or prevent disease. It is not a safety finding in either direction.

Is "supports healthy blood sugar" a disease claim?

Wording like that is written to stay on the structure/function side, because it does not name a disease. But the FDA looks at the context, including the product name, images, and any cited research, so the surrounding page can change how the same words are read.

Who do I tell if a supplement page promises to treat a disease?

You can report a problem product to the FDA using the steps on its page about reporting a problem with dietary supplements. For deceptive advertising, the FTC also accepts fraud reports on its website.

None of this is medical advice. If you are managing a condition, a supplement should never replace what your doctor has prescribed, so raise any product you are considering with your doctor or pharmacist first.