Royal Society criticises Lancet publication of GM research

The Royal Society has criticised the Lancet medical journal's decision to publish the results of studies by Professor Stanley Ewen and Dr Arpad Pusztai that claimed to show that genetically modified foods may affect the intestines of rats.


The Royal Society says The Lancet‘s position as a reputable journal lends the results unwarranted respectability. The President of the Royal Society, Sir Aaron Klug OM, said “the Royal Society would not have published this paper … since it confirms the Society’s original judgement that the experiments on which this paper is based were flawed.”

Ewen and Pusztai fed rats on potatoes that had been genetically modified to contain a protein (lectin) found in snowdrops, which increases potato plants’ resistance to attacks by insects and worms. They found that the cells of the stomach and parts of the intestine were thinner, and concluded, “the possibility that a plant vector in common use can affect the mucosa of the gastrointestinal tract…may also apply to GM plants…such as soya beans or any plants expressing lectin genes.”

The Royal Society presented its analysis of Dr Pusztai’s experiments in May 1999 following their screening on ITV’s World in Action programme in August 1998 and their availability on the World Wide Web from February 1999.

The new Lancet paper is based on the work analysed by the Royal Society in May. “Like that work, it is flawed,” said Sir Klug. “Too few animals were used to give statistically significant results for the complex phenomena being examined; the diets used were incompletely controlled; no control group of rats was fed a reduced protein diet. This omission is important because the GM potatoes contained less protein than normal potatoes. Once again, there was a lack of rigour in the experimental design and statistical interpretation.

“On the basis of this paper, it is not possible to conclude, as Professor Ewen and Dr Pusztai do, that the process of genetic modification of plants, or even the particular genes inserted into these GM potatoes, raise concerns for human health,” said Sir Klug.

The Lancet does not, however, see itself as endorsing Dr Pusztai’s conclusions. Along with the Pusztai results, The Lancet has published a report on the possible effects of GM foods on human blood cells, plus commentaries on the two research letters by the editor of The Lancet, Richard Horton, and Harry Kuiper and colleagues from the Netherlands State Institute for Quality Control of Agricultural Products.

Kuiper and colleagues are critical of the results reported. They write that “the experiments…were incomplete, included too few animals per diet group, and lacked controls…the results are difficult to interpret and do not allow the conclusion that the genetic modification of potatoes accounts for adverse effects in animals.”

In his commentary, Richard Horton explains why, despite criticism of Ewen and Pusztai’s experiments, The Lancet is publishing their results and points out that they were reviewed by six expert advisers and that the Research letter went through several revisions before it was accepted for publication.

Horton says The Lancet‘s reviewers disagreed about whether this work deserved publication, although a majority were in favour and quotes one of The Lancet‘s own expert reviewers: “I would like to see [this work] published in the public domain so that fellow scientists can judge for themselves… if the paper is not published, it will be claimed there is a conspiracy to suppress information.”

The research letter by Brian Fenton and colleagues from the Scottish Crop Research Institute and Nutrition Research Group in Dundee, UK, reports that snowdrop lectin binds strongly to a human white blood cell protein. The health implications of this binding are unknown, but the authors say that, “this work highlights the need for a much greater understanding of the interactions between plant lectins and human glycoproteins before they can safely be incorporated into the food chain.” Kuiper and colleagues agree, “such investigations will be of paramount importance for future generations of GM foods.”

Horton also notes that many professional pronouncements about GM food, “reflect a failure to understand the new, and apparently unwelcome, dialogue of accountability that needs to be forged between scientists and the public. Risks are not simply questions of abstract probabilities or theoretical reassurances. What matters is what people believe about these risks and why they hold those beliefs. Ewen and Pusztai’s data are preliminary and non-generalisable, but at least they are now out in the open for debate.”

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