Patrick Holford has made a fortune selling micronutrient products. His marketing technique is to make exaggerated or unsubstantiated claims. Although his business is based in the UK, he sometimes tours South Africa and markets his products here.

Recently he has been running an advertisement on Highveld Stereo and KFM, two popular radio stations, in which he claims his product, Smart Kids Brain Boost, will help children get to the top of their class. In its mildest form this is a claim that Holford's product improves mental performance. There is no evidence to support this.

The product sells for R149.95 on Holford's website. Clearly this is not a product that the parents of undernourished children could afford.

Holford is also calling for volunteers for a clinical trial of one of his products. It is against the law in South Africa to test medicines on people without the approval of the Medicines Control Council.

Here are some of the responses to Holford's claims about his children's products.

• Equal Education has lodged a complaint with ASASA against the radio adverts. (Declaration of interest: I serve on the board of Equal Education.)

• Harris Steinman has written a brilliant and short rebuttal of Holford's claims.

• Holford's claim has been added to the Quackbase.

• A lengthier version of Harris Steinman's rebuttal is also in the Quackbase. Steinman has examined every reference that Holford has cited in support of his product and shown that they do not substantiate his claims.

• HolfordWatch has dealt with similar claims by Holford in 2008. Here are part one and part two of their rebuttals.