Structure/function vs disease claims: the line that defines US supplement marketing

"Supports a healthy immune system" is fine. "Treats colds" is not. The difference between those two sentences is the difference between a legal supplement claim and an illegal drug claim — and it is one of the most consequential lines a US supplement brand has to walk. Cross it, and your supplement is, in the FDA's eyes, an unapproved drug.

Two kinds of claim

US supplement claims fall into categories, and the two that matter most here are structure/function claims and disease claims.

A structure/function claim describes the role of a nutrient or ingredient in affecting the normal structure or function of the body — for example, that calcium supports bone health, or that an ingredient helps maintain a normal function. These are permitted for supplements, within rules.

A disease claim states or implies that a product diagnoses, treats, cures, mitigates, or prevents a disease. Claims like this are reserved for approved drugs. A supplement that makes one is treated as an unapproved drug — a serious problem.

Where the line falls

The boundary is about disease. Talking about supporting the body's normal functioning is structure/function territory; claiming to act on a disease crosses into drug territory. "Supports cardiovascular health" leans one way; "lowers cholesterol to prevent heart disease" leans the other.

The difficulty is that the line is not always obvious. Implied disease claims — through wording, imagery, product names, or context — can cross it just as surely as explicit ones. The whole impression a claim creates is what counts, not just the literal words.

The mandatory disclaimer

Structure/function claims on supplements come with an obligation: a disclaimer stating that the claim has not been evaluated by the FDA and that the product is not intended to diagnose, treat, cure, or prevent any disease. This disclaimer is a standard, recognisable feature of US supplement labels for good reason — it is required when such claims are made.

The FDA has signalled that aspects of how and where this disclaimer must appear may be revisited over time, so the practical details are worth keeping an eye on. The underlying principle — structure/function claims carry a disclaimer, disease claims are off-limits — is the stable part.

Because the rules around claims and the disclaimer are subject to change, confirm the current FDA requirements before finalising claims and labels.

Claims must be truthful and substantiated

Staying on the structure/function side of the line is necessary but not sufficient. A claim must also be truthful, not misleading, and substantiated by adequate evidence. A permissible type of claim that is not actually supported by the product or the science is still a problem — a theme that connects to advertising rules as well as labeling.

The link to the formula

A structure/function claim implicitly rests on the product actually containing a meaningful amount of the ingredient behind the claim. A claim about an ingredient the product barely contains is hard to defend. So claim and composition are linked: the formula has to support the claim being made.

This is the same discipline that governs claims in other markets — the claim should follow from what the product genuinely delivers, not from marketing ambition.

Keeping claims compliant in practice

The sustainable approach is to treat claims as something derived from and tied to the product. Keep each claim mapped to the ingredient and amount that supports it, ensure it stays on the structure/function side of the disease line, and attach the required disclaimer where it applies. When a formula changes, the claims that depended on it can be re-checked rather than left stranded on an out-of-date label.

The takeaway

In the US, structure/function claims about the body's normal functioning are allowed — with a mandatory disclaimer — while disease claims turn a supplement into an unapproved drug. The line is about disease, including by implication, and every permissible claim still has to be truthful, substantiated, and supported by the formula. Treating claims as tied to composition is what keeps a brand on the right side of the most important line in US supplement marketing.

Lemoniq keeps claims tied to the ingredients and amounts that support them, so the claims on your US products follow what the formula actually delivers — and stay on the right side of the line. We solve this exact problem. See how it works