Structure/Function Claims: What Supplement Emails Can Say

Supplement brands live and die by retention. Customers who reorder every 30 days are the whole business model, and email and SMS are how you keep them. That also makes your inbox the place you’re most likely to break the rules on claims, because the copy is written fast, shipped weekly, and full of customer reviews you didn’t write.

This guide covers what supplement brands can and can’t say in email and SMS: the US structure/function framework under DSHEA and 21 CFR 101.93, the FTC’s substantiation standard for health advertising, and how it works in Australia under the TGA, where the rules are stricter and structured completely differently.

Regulator sources checked September 2026. This is general information, not legal or regulatory advice.

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What is a structure/function claim?

A structure/function claim describes how a nutrient or dietary ingredient affects the normal structure or function of the human body, such as “calcium builds strong bones.” In the US, supplements can make these claims without FDA approval, but they must be truthful and substantiated, notified to FDA within 30 days, carry FDA’s disclaimer, and never claim to treat or prevent disease.

The framework comes from the Dietary Supplement Health and Education Act of 1994 (DSHEA), and the detailed rules are in 21 CFR 101.93. FDA’s structure/function guidance gives the textbook examples: “calcium builds strong bones” and “fiber maintains bowel regularity”.

DSHEA allows three related types of statement on supplements:

Claim type	What it is	Example
Structure/function	Effect on normal structure or function of the body, or the mechanism by which an ingredient maintains it	”Magnesium supports normal muscle function”
General well-being	Well-being from consuming a nutrient or ingredient	”Supports your overall wellness routine”
Nutrient deficiency	Benefit related to a classical nutrient deficiency disease, which must state how common the disease is in the US	Vitamin C and scurvy

These are different from health claims (the relationship between a substance and reduced risk of a disease), which need FDA authorisation. For email purposes, structure/function is the category you’ll use every day.

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The four rules for US structure/function claims

1. Substantiation. You must have evidence the claim is truthful and not misleading. The FTC sets the bar for advertising: “competent and reliable scientific evidence”, which its Health Products Compliance Guidance (December 2022) says generally means randomised, controlled human clinical trials.
2. FDA notification. Under 21 CFR 101.93(a), you notify FDA no later than 30 days after first marketing a supplement with the claim.
3. The disclaimer. Under 101.93(c), the claim must be accompanied by: “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.” It must sit next to the claim or be linked to it with a symbol such as an asterisk.
4. No disease claims. Under 101.93(f) and (g), the statement must not be a disease claim, explicit or implied.

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Structure/function vs disease claims: where the line is

Under 101.93(g)(2), a statement is a disease claim if it says or implies that the product has an effect on a specific disease or class of diseases, on the characteristic signs or symptoms of a disease, or on an abnormal condition that’s uncommon or can cause significant or permanent harm, among other criteria. Crucially, the claim doesn’t have to be explicit. Under 101.93(g)(2)(iv) it can be implied through:

• (A) the product name
• (B) statements about formulation, such as containing an ingredient well known as a drug for treating a disease
• (C) citing a publication whose title refers to a disease use
• (D) using the term “disease” or “diseased” about a specific disease
• (E) pictures, vignettes, symbols or other means.

That last one matters for email, which is mostly pictures.

Email copy swaps

These pairs illustrate the distinction. Whether a specific claim is substantiated for your product is a separate question for your regulatory adviser.

Structure/function framing	Disease claim (avoid)
Supports restful sleep	Treats insomnia
Supports a healthy immune system	Prevents colds and flu
Supports joint comfort and mobility	Relieves arthritis pain
Promotes a sense of calm	Treats anxiety or depression
Supports healthy digestion	Cures IBS, relieves bloating from IBS
Helps maintain healthy blood sugar levels already within the normal range	For diabetics, lowers blood sugar
Supports cognitive function	Prevents memory loss, fights dementia
Supports healthy skin	Clears acne, treats eczema

Watch the context, not just the sentence. “Supports immune function” is fine; the same line in a “cold and flu season survival kit” email with a picture of someone in bed with a thermometer can imply disease prevention.

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Where supplement emails and SMS go wrong

Email and SMS aren’t product labels, but they’re squarely inside the rules. The FTC’s health guidance applies to advertising in every format, including digital and social, and FDA has long looked at a product’s promotional materials to judge its intended use. These are the most common failure points in supplement email programs.

1. Subject lines and preview text

Short copy pushes writers towards the sharpest claim: “Beat the flu this winter”, “Finally, relief from joint pain”. Subject lines are claims too, and they’re read by more people than the email body.

2. Review and UGC blocks

Klaviyo makes it easy to pull reviews into flows and campaigns. The FTC is explicit that testimonials don’t substantiate a claim, and that “results not typical” disclaimers don’t cure the deception. If a five-star review says “this cured my migraines” and you put it in an email, it’s now your disease claim. Filter review blocks by product and by keyword, and curate them manually for high-volume flows.

3. Condition-based segmentation

Quiz funnels that ask “What are you struggling with?” and then send “Your plan for managing anxiety” turn segmentation into a disease claim. Frame quiz outcomes around goals (“better sleep”, “calm focus”), not conditions. It’s also better practice for handling sensitive health data.

4. Imagery

Hospital settings, clinicians in scrubs, before-and-after photos of a skin condition, a person clutching their lower back. Under 101.93(g)(2)(iv)(E), pictures can make the disease claim your copy carefully avoided.

5. “Clinically proven”, “doctor recommended” and “FDA”

“Clinically proven” needs the clinical evidence to support the specific claim for your product at your dose. “Doctor recommended” needs to be true and representative. And never say or imply that your product or claims are “FDA approved”. FDA doesn’t approve supplements or structure/function claims.

6. The disclaimer as a fig leaf

Including the DSHEA disclaimer in your email footer is sensible practice when your email makes structure/function claims. But the FTC’s guidance is clear that the FDA disclaimer doesn’t satisfy FTC requirements and won’t rescue a misleading ad. It isn’t a licence to make disease claims.

7. SMS brevity

A 160-character SMS has no room for nuance. Keep text messages to offers, reorders and product news, and let the landing page carry the claims, with proper context and the disclaimer. SMS also has its own consent rules. See our SMS marketing service.

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Australia: TGA rules for supplement marketing

Australia doesn’t use the US structure/function model. What you can say depends on how your product is regulated.

Listed complementary medicines (AUST L)

Most vitamins, minerals and herbal supplements in Australia are listed medicines on the Australian Register of Therapeutic Goods (ARTG). The TGA requires that:

• Indications come only from the TGA’s permitted indications list. You can’t write your own claims the way US brands do. Your product’s claims are the indications on its ARTG entry.
• Advertising must be consistent with those permitted indications and must not be about treating serious illnesses. The TGA gives influenza and chronic asthma as examples.
• Advertising must comply with the Therapeutic Goods Advertising Code 2021: accurate, balanced, not misleading, and promoting safe and proper use.

The Advertising Code has specific rules that catch email marketers:

• Mandatory statements. Advertising for medicines must prominently display the required statement, for example “Always read the label and follow the directions for use”, and the TGA’s guidance says these must be clearly visible, not buried.
• Testimonials. The TGA prohibits testimonials from people engaged in producing, marketing or supplying the goods, which includes anyone who received valuable consideration, such as a paid influencer or someone given free product in exchange for a review. Testimonials from current or former health practitioners and professionals are also prohibited. Testimonials must be consistent with the product’s ARTG indications and describe typical benefits.
• Restricted and prohibited representations. Claims about serious diseases and conditions need specific TGA approval or are prohibited outright.
• Weight management products have additional restrictions, including on testimonials and statistics that are inconsistent with the results consumers would typically achieve.

For Australian brands, the review-block problem is sharper than in the US. A review from a customer who got a free bottle in a seeding campaign can’t legally be used as a testimonial in your email at all.

Supplements sold as foods

Some products, such as protein powders and functional foods, are regulated as foods rather than therapeutic goods. Their health claims fall under FSANZ Standard 1.2.7. General level health claims must be based on one of the more than 200 pre-approved food-health relationships, or on a self-substantiated relationship established by systematic review and notified to FSANZ before use. Claims referring to serious diseases (high-level health claims) are far more restricted.

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Pre-send checklist for supplement emails and SMS

• No disease names, symptoms of disease, or words like “treat”, “cure”, “prevent”, “heal” or “relieve [condition]”
• Subject line and preview text checked with the same rigour as the body
• Review and UGC blocks filtered, with no disease language and no incentivised reviews (Australia)
• Imagery doesn’t imply illness or treatment
• No “FDA approved”; “clinically proven” only with product-specific evidence on file
• US: DSHEA disclaimer present and linked where structure/function claims appear; FDA notification filed for each claim
• Australia: claims match ARTG permitted indications; mandatory statement included; no paid, gifted or health-professional testimonials
• Quiz and segment names framed around goals, not conditions
• New claims reviewed by your regulatory adviser before they go into an evergreen flow

That last point is where the risk concentrates. A campaign is sent once. A flow email with a bad claim sends every day for years. Whatever email flows your supplement brand runs, build the claim review in before a flow goes live, not after.

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Compliant doesn’t mean boring

The best-performing supplement emails rarely rely on medical claims anyway. They sell the routine, the reorder convenience, the ingredient story, the founder and the community. Replenishment timing, segmentation built around purchase behaviour and subscription saves do more for lifetime value than a riskier subject line.

We’ve built retention programs for supplement brands including Relaxium. If you want a Klaviyo program that grows repeat revenue without making your regulatory adviser nervous, see how we work with supplement brands, or start with a free Klaviyo audit.

This article is general information, not legal or regulatory advice. Claims and substantiation should be reviewed by a qualified regulatory professional for each market you sell into.