Two CAP Code rules do the work. Rule 12.1 requires evidence for any health claim, and CAP says it has yet to see evidence that nutritional therapy can treat or prevent disease. Rule 12.2 says a claim to diagnose, treat or help a medical condition is unacceptable unless the advertiser is suitably qualified, and claims about conditions that need medical supervision are off limits unless that supervision is in place.
Between them, those two rules quietly invalidate a great deal of nutritionist website copy, and almost nothing written for the profession explains them in plain terms.
Why does this fall differently for nutritionists?
Because the CAP test is about credentials and accountability, not about how much you know.
The CAP Code treats a health professional as suitably qualified where they can show relevant qualifications, a system for regularly reviewing their skills, suitable indemnity insurance, and accreditation by a professional or regulatory body that handles complaints, takes disciplinary action and registers people against minimum training standards.
A dietitian is HCPC registered, so every one of those boxes is ticked by a statutory regulator with fitness-to-practise powers.
A nutritionist is not statutorily regulated. As our guide to whether you can call yourself a nutritionist sets out, the Association for Nutrition says so itself: the term is not regulated by law. Membership of a voluntary register with a complaints process can go some way towards the accreditation part of the test, but it does not get you past rule 12.1: being qualified to make a claim is not the same as having the evidence for it.
So the same sentence on two websites can be acceptable on one and a breach on the other, depending on who wrote it and what evidence sits behind it. That feels unfair to practitioners who have trained seriously, and it is nonetheless the position. Where you are unsure about a specific claim, CAP's free Copy Advice service will tell you before you publish.
What has CAP actually said about nutritional therapy?
Directly, and it is worth quoting because it sets the evidential baseline.
CAP's advice on nutritional therapy states that the ASA and CAP have yet to see evidence that nutritional therapy can be used to treat or prevent disease or medical conditions.
It also warns specifically against detox claims, and cautions that condition-specific claims risk discouraging people from seeking essential treatment unless the work is supervised by a suitably qualified professional.
And it warns nutritional therapists not to blur themselves with the protected terms "dietitian" and "dietician", which is a criminal offence under Article 39 of the Health Professions Order 2001 where used with intent to deceive.
What does an actual ruling look like?
Adjudications against individual practitioners in this area exist but are not numerous in recent years, at least not that we could surface. The ASA rulings database returned errors during our searches, so the picture here is incomplete.
The clearest verified example is Optimum Health UK, upheld on 19 October 2011, where claims about removing toxins and improving cellular energy were found to be unsubstantiated.
The age of that ruling is not a reason to relax. It reflects that most non-compliant copy is quietly amended after an informal approach rather than proceeding to a published adjudication.
What can you actually say?
More than the restrictions suggest, if you frame it as description rather than as an outcome claim.
Safe territory:
- What you do: nutritional assessment, dietary analysis, personalised eating plans, coaching and accountability
- Your qualifications and register membership, stated accurately
- General wellbeing and healthy eating, without naming conditions
- What a consultation involves, which is often what a prospective client actually wants to know
Territory that needs substantiation you probably do not have:
- Naming a medical condition you treat or help
- Anything about diabetes, blood pressure, obesity or other conditions requiring medical supervision, which are CAP's own examples
- Detox, toxin removal, cellular claims
- Testimonials that make efficacy claims you could not make yourself
That final point catches people. A client saying you fixed their IBS is a claim about treating a medical condition, and republishing it on your site means you made it.
The second rulebook: products
Separate from claims about your service, if you promote a food or supplement you are in the nutrition and health claims regime.
Only claims on the GB Nutrition and Health Claims Register may be used, the authorised wording must be used exactly rather than paraphrased, and the product must meet the conditions attached to that claim. Our guide to health claims for dietitians sets out that regime in more detail, and it applies identically to nutritionists.
What about working with a supervising professional?
Worth knowing, because it is the route CAP itself gestures at.
Where condition-specific work is supervised by a suitably qualified health professional, such as a dietitian or doctor, the position changes. A nutritionist working within a clinic alongside a dietitian or a doctor, with genuine clinical oversight, is in a different position from one working alone.
That has to be a real arrangement rather than a label. But it is a legitimate structure, and it is worth considering if condition-specific work is central to what you want to offer.
A practical audit
- Search your own site for condition names. Diabetes, IBS, PCOS, thyroid, menopause, fatigue. Each instance needs substantiation or rewriting
- Rewrite claims as descriptions of service rather than promises of outcome
- Check testimonials and reviews you republish
- Remove detox and toxin language entirely
- Check your social media, which is in scope and is usually written faster and less carefully than your site
- Use CAP's free Copy Advice service before publishing anything borderline
That last one is genuinely under-used across every discipline we have looked at. CAP will tell you in advance whether wording is acceptable, which is cheaper and less stressful than finding out afterwards.
This is general information about advertising rules, not legal advice. The CAP Code and its guidance are updated, and whether a particular practitioner counts as suitably qualified is decided case by case. Check the current position and consider CAP's Copy Advice service.
Sources: ASA/CAP, nutritional therapy · ASA/CAP, health therapies and references to medical conditions · GB Nutrition and Health Claims Register
Related: Can I call myself a nutritionist without a degree? · What health claims can a dietitian make? · Can nutritionists order blood tests?
