Note: This advice is given by the CAP Executive about non-broadcast advertising. It does not constitute legal advice. It does not bind CAP, CAP advisory panels or the Advertising Standards Authority.

Marketers should hold substantiation for the claims they make in marketing communications. When they make medical and scientific claims about health-related products, that evidence should probably consist of trials conducted on people (Rules 3.7 and 12.1. See also Help Note on Substantiation for Health, Beauty and Slimming Claims).

The purported benefits of magnets and magnetic devices have been advertised for many types of product: human-health and pet-health products (NRG Magnetic Products, 9 October 2002; Zarifeh Ltd, 10 July 2002; Ecostar, 21 November 2001, and Magnetic, 23 May 2001), water softeners (Direct & Specialised Distribution Company Ltd, Modern Originals, 10 January 2007; The Tensor Marketing Ltd t/a The Factory Shop, 3 July 2002; Temps L, 27 June 2001, and Ecoflow, 25 April 2001), shields against mobile phone radiation and fuel accessory products (Spirit of Nature, 12 March 2008; Ecoflow, 17 April 2002; PP Innovations Ltd, 8 January 2003, and Magna Jewellery Ltd, 19 December 2001). CAP is aware that other magnetic products claim to relieve ulcers, period pain, arthritic pain, sciatica, rheumatism, migraines, restless leg syndrome and the symptoms of the Menopause and cure impotence. Neither the ASA nor CAP has accepted that the claimed benefits are supported by satisfactory scientific evidence. Although some people might believe in the powers of magnets, marketers should remember that testimonials alone do not constitute substantiation (rule 3.47 and Magnetic, 23 May 2001, in which the marketer provided genuine testimonials but did not prove the efficacy of the product).

Although rules 3.13 and 3.6 allow an advertiser to make product claims with which others may disagree, the Code requires claims to be backed by respectable evidence. Introduction IV(c) explains that conformity with the Code will depend on "the medium in which the marketing communication appeared, the audience and its likely response, the nature of the product and any material distributed to consumers". CAP and the ASA recognise that readers are likely to expect some claims to be more clear, and evidence more robust, than others; for example: a claim directed at a vulnerable group of consumers that a product is likely to have a real impact on their health. Such a claim (whether express or implied) is likely to require strong supporting evidence because of health and safety concerns and because consumers are used to tight statutory and non-statutory regulation in health-related matters.

In addition to holding convincing proof for the efficacy of magnetic products, marketers of health-related products have to ensure they do not invite consumers to self-diagnose or self-treat (Magnetic, 23 May 2001, and Snowden Healthcare Ltd, 15 September 2004) or refer to serious or prolonged ailments (Zariefeh Ltd, 10 July 2002). Marketers may make claims for products such as "magnetic knee straps" only if they make absolutely clear that any temporary, positional relief results from the support offered by the strap and not from the magnets. Furthermore, the strap should have been designed for that purpose and the mention of the magnets must be incidental; implied claims for the efficacy or role of the magnets in such products are likely to be unacceptable (Magnopulse Ltd, 16 March 2005.)

See 'Medical Devices' and ‘Therapies: Magnetic Field Therapy'.

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