FDA publishes warning letters on its website, and the pattern across hundreds of letters to supplement and food brands is consistent. The same violations appear repeatedly, across different categories, different company sizes, and different price points. That consistency means something: these violations aren't rare edge cases. They're the predictable output of the compliance gaps that most brands have.
Understanding what FDA cites most often isn't just defensive. It's a diagnostic — a way to identify where your current compliance process may have the same vulnerabilities that led to enforcement action against similar brands.
Disease Claims: The Most Cited Supplement Violation
The single most common violation in FDA warning letters to dietary supplement brands is the disease claim: a statement on the label, website, or advertising that characterizes the product as diagnosing, curing, treating, mitigating, or preventing a specific disease. Disease claims convert a supplement into an unapproved new drug.
What makes disease claims the most cited violation is partly the scale of the problem — the supplement industry has tens of thousands of products with health benefit claims — and partly where the claims appear. Warning letters regularly cite marketing language that never appeared on the physical label: website copy, Amazon product descriptions, social media posts, YouTube video descriptions, and influencer content.
FDA's enforcement posture is that the totality of a brand's marketing determines the intended use of the product. A supplement label with compliant structure/function claims, paired with website copy saying the product "treats anxiety" or "lowers blood sugar," is making disease claims. The label compliance alone isn't a defense.
What disease claims typically look like in warning letters
Warning letter citations for disease claims follow a consistent pattern. The letter quotes specific language from the brand's website, social channels, or marketing materials. Common quoted language includes:
Explicit disease references: "treats diabetes," "prevents heart disease," "cures cancer," "manages hypertension"
Symptom-based claims that imply disease treatment: "reduces pain and inflammation," "relieves arthritis symptoms," "lowers blood pressure"
Recovery claims: "helps the body heal from," "restores normal function after," "aids recovery from"
Mental health claims: "treats depression," "reduces anxiety," "helps with PTSD"
The pattern in warning letters is that brands underestimate how far their marketing extends. A product detail page on a brand's website is, in FDA's view, part of the product's labeling. An influencer post that a brand paid for and didn't correct is the brand's own advertising.
Unsupported Structure/Function Claims
Even when a claim doesn't cross into disease claim territory, it can still draw a warning letter if it isn't substantiated. DSHEA requires that structure/function claims be supported by competent and reliable scientific evidence. FDA's interpretation of that standard, applied in warning letters, means human clinical evidence for efficacy claims — not just mechanistic rationale or generally recognized safety.
Warning letters citing unsupported claims typically target specific ingredient-claim combinations where the claimed benefit isn't supported by human trial data: proprietary blends where the individual ingredient doses are below studied efficacy levels, ingredients whose claimed effects have only been studied in vitro or in animals, or ingredients where the claimed benefit doesn't match the available evidence.
The structure of the violation: a brand claims "supports healthy testosterone levels" for an ingredient that has no peer-reviewed human evidence of testosterone-related effects. The claim may be within the structure/function framework linguistically, but it lacks the substantiation that makes it compliant.
Missing or Altered DSHEA Disclaimer
Warning letters frequently cite DSHEA disclaimer violations: the disclaimer is missing entirely, is paraphrased or abbreviated, or appears in a context that obscures it. Under 21 CFR 101.93, the disclaimer must be verbatim, present on the label, and displayed prominently. The exact language is required: "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."
Common violations:
"Not evaluated by the FDA" (abbreviated — not compliant)
Disclaimer present on the label but missing from the website where claims appear
Disclaimer placed in small type on the back panel while claims appear prominently on the front
Disclaimer absent from a product that makes structure/function claims
cGMP Violations in Supplement Manufacturing
A significant share of warning letters to supplement brands cite current Good Manufacturing Practice (cGMP) violations under 21 CFR Part 111, typically resulting from FDA facility inspections rather than label review. Common cited violations:
Identity testing failures: Part 111 requires 100% identity testing of every dietary ingredient before use. Warning letters cite facilities that rely exclusively on supplier certificates of analysis without conducting their own identity testing — or that test a sample rather than every lot.
Batch production record failures: Manufacturing records must document every step of the production process for every batch. Warning letters cite incomplete records, batch records that don't match master manufacturing records, or records that were completed after production rather than contemporaneously.
Master manufacturing record deficiencies: The MMR must include complete specifications for the finished product, every step in the manufacturing process, and the quality controls at each step.
Finished product testing gaps: All finished products must meet identity, purity, strength, and composition specifications before release. Warning letters cite companies that release product without adequate finished product testing.
These violations are significant because they question the reliability of every product from the facility — not just the specific products flagged for label violations.
Allergen Labeling Violations
Undeclared allergens remain one of the most cited food label violations, and a significant source of FDA recall requests. Warning letters and recall events cite:
Allergen present in a compound ingredient or flavoring system that wasn't declared on the label
Sesame present in a spice blend, flavoring, or processing ingredient that was added to the allergen list in 2023 but never reviewed
"Contains:" statement that doesn't include all allergens in the product
Shared equipment advisory language missing when cross-contact risk is real
The allergen violations that generate enforcement actions are almost always the result of process failures — a supplier reformulation wasn't reviewed, a new ingredient wasn't assessed for allergen content, the specification sheet was out of date. The brand often had no idea the allergen was present until the recall.
Nutrient Content Claim Violations
Warning letters cite nutrient content claim violations with some regularity, most often for claims that don't meet their threshold:
"High protein" on products with ≤19% DV protein per serving (threshold is ≥20%)
"Low sodium" on products with >140mg sodium per serving
"Sugar free" without the required "not a low calorie food" or equivalent disclosure
"No sugar added" on products where the food normally contains no added sugars anyway (the claim implies a meaningful departure from standard)
"Light" claims without the required reference food comparison and reduction disclosure
These violations are particularly common in new product categories — functional beverages, protein snacks, fortified foods — where marketing teams familiar with conventional food claims apply them to products that don't quite meet the thresholds.
FTC Enforcement Running Alongside FDA
FTC enforcement against supplement and food brands runs parallel to FDA's, and the violations overlap substantially. FTC citations focus on unsubstantiated health claims, deceptive testimonials, and inadequate disclosures for paid influencer endorsements.
FTC's substantiation standard for health claims — "competent and reliable scientific evidence" — is interpreted to require at least two well-designed, double-blinded, placebo-controlled human trials for efficacy claims. Weight loss claims, cognitive enhancement claims, and disease treatment claims are the highest-focus categories.
FTC warning letters and consent orders also cite:
Testimonials that present atypical results without required disclosures ("results not typical")
Paid influencer posts without clear sponsorship disclosure
"Buy one get one free" pricing that misrepresents the regular price
What Warning Letter Patterns Tell You
The regularity of the violations in FDA warning letters — disease claims, missing disclaimers, unsupported claims, allergen failures — means that any supplement or food brand with a large catalog and active marketing is statistically likely to have at least some of the same vulnerabilities. The brands that don't receive warning letters aren't necessarily more knowledgeable about the regulations. They're more likely to have systems that catch violations before enforcement does.
Get Ahead of Enforcement — Not Behind It
FDA posts new warning letters weekly. Reviewing them is useful market intelligence — the violations FDA is actively citing tell you which claims are drawing the most scrutiny in your category. Truli's Regulatory Radar monitors FDA warning letters and enforcement actions relevant to your product categories and surfaces the patterns that matter for your brand. The AI compliance platform audits labels, marketing copy, and social content against current regulations before violations make it into enforcement. Book a demo to see how Truli monitors the regulatory environment for your brand.
