Can I say "boosts immunity" in a UK supplement ad?
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Short answer. No. CAP advises against saying a supplement "boosts", "strengthens" or "optimises" the immune system. The authorised wording is "[nutrient] contributes to the normal function of the immune system", and you can only use it if your product contains enough of a nutrient that has this claim on the GB register, such as vitamin C. Words like "supports" or "helps" are fine when they stay tied to normal immune function.
Why "boost" is a problem
- It changes the meaning of the authorised claim. The register says a nutrient contributes to normal function. "Boost" suggests more than normal, which exaggerates the claim (CAP rule 15.1).
- "Immunity" can imply protection from illness. CAP warns that it can be read as protection against disease, and a food or supplement must not claim to prevent, treat or cure disease (rule 15.6.2).
- No colds, flu or viruses. Don't refer to them, directly or by implication, in ads for supplements.
What to write instead
| Instead of | Write (if your product meets the conditions of use) |
|---|---|
| Boosts your immunity | Vitamin C contributes to the normal function of the immune system |
| Strengthens your immune system | With vitamin C, which supports the normal function of the immune system |
| Immune booster | Immune support with vitamin C* (*vitamin C contributes to the normal function of the immune system) |
| Protects you from colds | Remove it. It's a disease claim |
Check the register for your exact nutrient. Vitamin C, vitamin B12, selenium and iron are among the nutrients with an authorised immune claim, each with its own conditions of use.
The same pattern for other common words
- "Superfood", "full of goodness", "detox": general health claims. Only allowed with an authorised specific claim next to them (rule 15.2).
- "Clinically proven": you must hold evidence for exactly what is claimed, and a health claim still has to be on the register.
Sources
Not legal advice. Last updated: 1 November 2026.