Can I say my supplement "boosts immunity"? A founder's guide to UK claims wording

The short answer

Usually, no. UK supplement marketing can only use authorised nutrition and health claims — wording from the GB register that links a specific nutrient to a normal function of the body. "Boosts immunity" is not that wording: it is a general, unauthorised efficacy claim, and it is one of the phrases regulators and the Advertising Standards Authority see most often.

That surprises a lot of founders, because "boost" language is everywhere. Its ubiquity is not evidence that it is allowed — it is evidence that a lot of supplement websites have never been reviewed.

What you can say instead

If your formula contains, say, vitamin C, vitamin D or zinc at meaningful levels, you can use the authorised wording those nutrients have earned — for example, "vitamin C contributes to the normal function of the immune system". The register wording is precise, but it names the nutrient, states a real function and, crucially, is legal to publish.

The craft is in the framing. An authorised claim can anchor a benefit-led section without the copy going beyond it: the page around the claim can talk about routines, quality, sourcing and the customer's goals, so long as the efficacy statements themselves stay inside the register.

The line you must never cross

A health claim links a nutrient to a normal function. A medicinal claim — treating, curing or preventing a disease — is a different legal category entirely: it turns your product into an unlicensed medicine and moves the conversation from the ASA to the MHRA. "Fights colds and flu" is not a bold health claim; it is a medicinal claim, and no supplement should make it.

Why compliant copy often sells better

Vague hype ("supercharge your immune system!") reads like every other supplement ad and invites scepticism. Register wording forces specificity — a named nutrient, a named function — and specificity is what sceptical modern buyers actually respond to. In our builds, the compliance pass and the conversion pass are the same discipline: find the strongest thing the formula has legitimately earned the right to say, then say it clearly.

What to do if your current site says "boosts"

Audit it before someone else does. Map every claim on every page — product pages, homepage, testimonials, image overlays — against the authorised register, reword what fails, and keep a record of what wording maps to which nutrient. This is exactly what our compliance review does, and it routinely finds that the reworded page converts as well as or better than the original.