A structure/function claim is a statement on a food or dietary supplement label that describes how a nutrient or ingredient affects the normal structure or function of your body. “Calcium builds strong bones” and “fiber maintains bowel regularity” are classic examples. These claims are allowed on product labels without FDA approval, but they come with specific rules, required disclaimers, and a clear legal boundary: they can never suggest that a product diagnoses, treats, cures, or prevents a disease.
How Structure/Function Claims Work
Structure/function claims fall into a few distinct categories. A claim can describe what a nutrient does for the body (“calcium builds strong bones”), explain the mechanism by which an ingredient maintains normal function (“antioxidants maintain cell integrity”), or reference the effect of a dietary supplement on general well-being. Claims about nutrient deficiency diseases are also permitted. A vitamin C supplement, for instance, can reference scurvy, because diseases caused by essential nutrient deficiencies are carved out from the broader definition of “disease” under these rules.
The key word in all of this is “normal.” Structure/function claims are about maintaining health that’s already there, not restoring health that’s been lost to disease. A probiotic supplement can say “supports digestive health.” It cannot say “treats irritable bowel syndrome.” That distinction is the legal backbone of the entire category.
The Line Between a Structure/Function Claim and a Disease Claim
The FDA draws a firm boundary between structure/function claims and disease claims. Only a drug can legally claim to diagnose, treat, cure, or prevent a disease. If a supplement label crosses that line, the product is considered an unapproved drug in the eyes of regulators, which opens the manufacturer up to enforcement action.
In practice, this means wording matters enormously. “Supports a healthy immune system” is a structure/function claim. “Prevents colds and flu” is a disease claim. “Promotes joint comfort” stays on the legal side. “Reduces arthritis pain” does not. The FDA applies the same interpretive framework to conventional foods and dietary supplements, so these rules aren’t limited to the supplement aisle.
What Manufacturers Must Do
Unlike health claims (which require FDA pre-approval), structure/function claims don’t need the agency’s sign-off before they appear on a label. But manufacturers aren’t completely free to print whatever they want. There are three requirements they must meet.
First, the manufacturer must have substantiation that the claim is truthful and not misleading before putting it on the label. The Federal Trade Commission, which oversees advertising for these products, defines the standard as “competent and reliable scientific evidence,” meaning tests, analyses, or studies conducted and evaluated objectively by qualified experts. The FTC has specified that this generally means randomized, controlled human clinical trials, the most reliable form of evidence. A manufacturer can’t simply point to animal studies or theoretical mechanisms and call it a day.
Second, the manufacturer must notify the FDA within 30 days of first marketing a supplement with a structure/function claim. The notification includes the exact text of the claim, the name of the dietary ingredient involved, the brand and product name, and the signature of someone who can certify that the information is accurate and that the company has substantiation on file. Each product must be listed individually; a generic reference like “for other brands” is not allowed. The FDA accepts these notifications through an electronic portal or by mail.
Third, the label must carry a mandatory disclaimer.
The Required Disclaimer
Every dietary supplement that carries a structure/function claim must display this two-part statement:
“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.”
This disclaimer is legally required, not optional. Its purpose is to make clear to consumers that the claim on the label hasn’t gone through the FDA’s review process and that the product is not a drug. If you’ve ever flipped over a bottle of vitamins or herbal supplements and seen that small block of text, that’s what it is. The first sentence signals that the FDA hasn’t weighed in on whether the claim is accurate. The second sentence reinforces the boundary between supplements and pharmaceuticals.
How This Differs From Health Claims
The FDA recognizes several types of claims that can appear on food and supplement labels, and they operate under very different levels of scrutiny. Health claims describe a relationship between a substance and a disease or health condition, like “diets low in sodium may reduce the risk of high blood pressure.” These require FDA authorization, either through a formal review process or through qualified health claim petitions that come with their own set of disclaimers about the strength of the evidence.
Structure/function claims sit at a lower tier of regulatory oversight. They don’t require pre-approval, just notification and substantiation that the manufacturer keeps on file. This makes them far easier for companies to use, which is why they’re the most common type of claim you’ll see on supplement labels. The tradeoff is that consumers bear more responsibility for understanding what these claims actually mean. “Supports heart health” sounds reassuring, but it tells you nothing about whether the product has been proven effective in clinical trials or reviewed by an independent body.
Why This Matters for Consumers
The structure/function claim system was established under the Dietary Supplement Health and Education Act of 1994, and it fundamentally shapes how supplements are marketed in the United States. Because manufacturers don’t need FDA pre-approval, the supplement aisle is filled with products making claims that sound medical but aren’t held to the same evidentiary standard as prescription or over-the-counter drugs.
That doesn’t mean every claim is baseless. Some structure/function claims are backed by strong research. Calcium genuinely does play a central role in bone health, and fiber genuinely does support bowel regularity. But other claims rest on thinner evidence, and the system places the burden on the FTC to challenge misleading claims after products are already on the market rather than screening them beforehand. When you see a structure/function claim on a label, it means the manufacturer believes it has adequate scientific backing, not that an independent agency has confirmed that’s true.