Rules for Supplement Advertising: What Sellers May and May Not Say

Ad Rules Plain is an independent guide to the rules for supplement advertising, written for shoppers who want to judge a health claim for themselves. It uses ProDentim, an oral probiotic sold as a dietary supplement, as a running example of how a seller's wording can be read, questioned and checked against the label. Nothing here is a verdict on a product; it is a method for reading ads.

What supplement advertising rules are, and what shoppers often get wrong

Supplement advertising is bound by a few broad ideas: claims should be truthful, a seller should be able to back up what it says, and a supplement may not be sold as a treatment for a disease. Shoppers often assume that a product on sale has been checked in advance, or that a confident sentence on a page has been tested. Neither is a safe assumption.

Another common mistake is treating a seller's description as a finding. When the seller of ProDentim says its formula uses three named probiotic strains, that is what the seller says, not an independent result. Learning to separate a description, a claim and evidence makes ads much easier to read.

Readers who want the product basics in one place can start with rules for supplement advertising.

Practical first steps, and when to see a dentist

Start with the label on the bottle itself rather than the sales page. Look for what is listed, what amounts are shown and what is missing. Notice who is speaking: a seller, a reviewer paid a commission, or a neutral source. Be wary of urgency, dramatic stories and promises about gums, teeth or breath.

No supplement replaces brushing twice a day with a fluoride toothpaste, cleaning between the teeth daily and regular dental checkups. See a dentist for pain, bleeding that persists, swelling, loose teeth, sores that do not heal, or breath or a taste that will not go away. Ask a dentist, doctor or pharmacist before trying any supplement if you are pregnant, breastfeeding, on medication or have a medical condition.

Guides in this series

Guide / Nov 2, 2026 / 2 min read

Truthful and Substantiated: The Core Advertising Rule

The core advertising rule is that claims must be truthful and the seller must be able to support them with suitable evidence before making them.

Guide / Oct 22, 2026 / 2 min read

Why Supplements Cannot Claim to Address Disease

Supplements can be marketed to affect general body function in limited ways, but selling one as a treatment or preventive for a disease is not allowed, which is why disease claims.

Guide / Oct 19, 2026 / 2 min read

The Structure-Function Disclaimer in Plain English

A structure function disclaimer is the small-print notice saying that a supplement's statements about supporting the body have not been evaluated by the FDA and that the product is not.

Guide / Oct 13, 2026 / 3 min read

Reporting a Misleading Health Ad

If you want to report misleading ad copy for a health product, save the ad, note exactly which claim bothers you, and send it to the advertising or consumer body in your own country, or to.

Guide / Oct 2, 2026 / 3 min read

Advertising vs Editorial: Telling Them Apart

Advertising vs editorial content comes down to who benefits and who controls the words.

Common questions

Does this site sell supplements or give medical advice?

No. It is an independent guide to reading supplement marketing. It does not sell anything and does not replace advice from a dentist, doctor or pharmacist.

Why is ProDentim mentioned?

It serves as an example of a supplement with a detailed seller page. Everything said about it is attributed to the seller or the label, and none of it is a promise of results.

Who should check with a professional before using an oral supplement?

Anyone who is pregnant or breastfeeding, anyone on medication, anyone with a medical condition or allergy, and anyone giving something to a child. A dentist, doctor or pharmacist can advise on your situation.