Structure/Function Claims: What Your Food Label Can and Cannot Say

Every week, food brands receive FDA warning letters — or worse, FTC enforcement actions — for label claims that crossed the invisible line from "structure/function" to "drug." Often, the brand didn't know the line was there. The product development team approved the language. The retailer asked for it. The marketing team wrote it. Nobody flagged it.

Understanding the structure/function claim framework is not optional if you are building a functional food or beverage brand. It is the difference between a product that can make health associations on-pack and a product that is, legally, an unapproved drug.

The Three-Category Framework

The FDA regulates health-related label claims under three distinct frameworks, each with different requirements:

1. Nutrient Content Claims

These describe the level of a nutrient in a product. They are defined, standardized, and require specific nutrient levels to qualify.

Examples: "Excellent source of fiber" (≥20% DV per serving), "Low sodium" (≤140mg per serving), "High protein" (≥10g per serving)

These are the safest claims to make — they have defined regulatory standards and do not reference health outcomes. If you meet the nutrient threshold, you can make the claim.

2. Health Claims

These link a specific nutrient or food to a reduced risk of a specific disease. They require either FDA authorization through the petition process (authorized health claims) or a qualified health claim with FDA review.

Example authorized health claim: "Adequate calcium and vitamin D as part of a healthful diet, along with physical activity, may reduce the risk of osteoporosis."

Unauthorized health claims — implying a nutrient reduces disease risk without FDA authorization — are prohibited. Most brands should not be in this territory without formal regulatory review.

3. Structure/Function Claims

These describe the role a nutrient or ingredient plays in the normal structure or function of the human body. They do not reference disease.

Examples:

• "Calcium builds strong bones" ✅
• "Fiber supports digestive regularity" ✅
• "Antioxidants support immune function" ✅
• "Iron is necessary for healthy red blood cell formation" ✅

Structure/function claims are permitted without FDA pre-approval for conventional foods and dietary supplements — but they require substantiation and, in the supplement context, specific labeling disclaimers.

The Disease Claim Line: Where Brands Get Into Trouble

The most common compliance failure is not flagrant disease promotion — it is claims that slip from structure/function into disease territory through specific word choices.

The pairing trap: A structure/function claim paired with disease imagery or context becomes a disease claim. "Supports heart health" with a graphic of a healthy heart is a structure/function claim. "Supports heart health" with a graphic of a blocked artery becoming clear is disease-adjacent. The FDA evaluates the totality of the label — not individual phrases in isolation.

The implication trap: "For people with diabetes" is a disease claim even without a specific claim about what the product does for the condition. Directing a product to a disease population creates a drug-context implication.

The "clinically proven" trap: This phrase implies a level of scientific validation that subjects the claim to heightened FTC scrutiny. If you cannot point to a published RCT (randomized controlled trial) using your specific product (or a closely comparable ingredient at the same dose), do not use "clinically proven."

Building a Compliant Structure/Function Claim

The process for building claims that hold up to regulatory scrutiny:

<ProcessFlow steps='["Identify the ingredient or nutrient: What specifically are you making a claim about? (A vitamin? An extract? A probiotic strain?)", "Define the functional endpoint: What does it do in the body? Be specific — 'supports immune function' is broad; 'supports normal T-cell production' is specific and more defensible", "Assemble substantiation: Gather the scientific literature on your ingredient at your dose level. A published systematic review is stronger than a single study. Your specific product is strongest.", "Screen for disease triggers: Read your claim draft and flag any word that references a disease, condition, symptom, or medical treatment. Remove or rephrase all of them.", "Apply the disclaimer if required: In supplement context, the DSHEA disclaimer is mandatory. In conventional food context, the disclaimer is not legally required but can be used defensively.", "Document and retain: Keep the substantiation file, the claim development rationale, and the regulatory review on file before the claim appears on any label or marketing material."]'>

The Substantiation Standard: What "Competent and Reliable Scientific Evidence" Means

Both the FDA (for food claims) and the FTC (for advertising) require "competent and reliable scientific evidence" to support health-related claims. This standard is not defined as a specific number of studies — it is a totality-of-evidence judgment.

Stronger substantiation:

• Multiple independent published RCTs using your specific ingredient, at your specific dose, in a population comparable to your consumer
• A published systematic review or meta-analysis covering your ingredient and endpoint
• A recognized expert consensus (e.g., scientific review panels that have evaluated your ingredient category)

Weaker substantiation:

• In vitro (cell culture) or animal studies without human confirmation
• A single RCT with a small sample size
• A study using a much higher dose than your product delivers
• A study on a related but different ingredient (a study on fish oil omega-3s does not substantiate claims for your plant-based ALA omega-3 product)

Dose matching is non-negotiable. This is the most common substantiation gap in functional food labeling. A study showing immune effects at 3,000mg of an ingredient does not substantiate a claim for a product delivering 300mg. The FDA and FTC both evaluate whether the dose in the supporting evidence is comparable to the dose in the product.

Common Structure/Function Claims by Category and Their Limitations

The FTC Advertising Dimension

The FTC governs advertising (including social media, influencer posts, and website claims), not label content. The FTC's standard for health claims in advertising is "substantiated" — meaning the claim must be truthful, not misleading, and supported by competent and reliable evidence.

What this means practically: A claim that is compliant on your label (structure/function, FDA-compliant) is not automatically compliant in your advertising. The FTC will evaluate whether the impression created by your advertising as a whole is substantiated. An Instagram post saying "our product cleared my brain fog" is a testimonial that implies a disease outcome (cognitive impairment) — even if your label only says "supports cognitive function."

Influencer disclosures are a separate but related issue. Any paid influencer making health-related claims about your product is, in the FTC's view, making claims on your behalf. Their claims must be substantiated and their compensation disclosed. Manage influencer content with the same rigor you apply to label review.

Key Takeaways

• Structure/function claims describe mechanism, not disease. Any reference to a disease name, disease symptom in a medical context, or treatment implication converts the claim to an unauthorized drug claim.
• Substantiation must be on file before the claim appears on anything. Dose matching is the most common gap.
• The FTC governs your advertising with the same (or higher) scrutiny as the FDA applies to labels. Your social media and website claims are regulated.
• The disclaimer is required in the supplement context and best practice in functional food claims. It does not excuse inadequate substantiation.