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The Health Effects of Consuming GM Products
The UK government financed two studies into the health effects of GM food, one on animals and one on humans. Both found negative effects which merit further investigation.
Dr. Pusztai´s Animal Experiments
Dr. Arpad Pusztai’s animal experiments at the Rowett Institute, Scotland, 1998, (SOAFED flexible fund project RO818) tested rats for effects from being feed GM potatoes. His experiments showed that rats fed on GM potatoes suffered a weakened immune system as well as impairment to the development of the internal organs. His research discovered gut lesions in rats following consumption of GM potatoes containing a gene from the snowdrop for lectin production. The rats were unaffected by non-GM potatoes or lectin alone. In a chapter co-authored by Dr. Pusztai in a book called “Food Safety: Contaminants and Toxins”, he comments, “the present crude method of genetic modification has not delivered GM crops that are predictably safe and wholesome.” (See: A. Pusztai, S. Bardocz and S.W.B. Ewen, ‘Genetically Modified Foods: Potential Human Health Effects’, Chapter 16 in Food Safety: Contaminants and Toxicants, edited by J.P.F. D’Mello (2003), CABI Publishing.)
Dr. Pusztai’s studies have been reviewed in a study conducted by dr. Ian F. Pryme, professor of biochemistry and molecular biology at the University of Bergen in Norway. The conclusion to this study stated, “In conclusion we feel that much more scientific effort and investigation is necessary before we can be satisfied that eating foods containing GM material in the long term is not likely to provoke any form of health problems.” (Ian Pryme and others, ‘Invivo Studies on Possible Health Consequences of GM Food and Feed – with particular regard to ingredients consisting of GM plant materials’, in Nutrition and Health 17 (2003) , p. 7.)
The Newcastle Study on Humans
In July 2002, the UK government body, Food Standards Agency, posted (on their website) the results of the world’s first known trial of GM food on humans. The study was conducted at Newcastle University and involved 19 volunteers; 12 normal healthy subjects and 7 people who had undergone an ileostomy (that is, removal of the lower part of the gut and diversion of digested food into a colostomy bag). The ileostomies were chosen as this allows the easy collection of digested food from the intestine. All subjects were given only ONE meal containing GM Soya food, and then tested to see if GM gene material passed from GM food into the intestines of the volunteers and subsequently into gut bacteria – a process called Horizontal Gene Transfer. (Note: The findings of those studies have since been published in a peer reviewed journal on biotechnology: T. Netherwood, S.M. Martin-Orue, A.G. O'Donnell, S. Gockling, J. Graham, J.C. Mathers and H.J. Gilbert, ‘Assessing the survival of transgenic plant DNA in the human gastrointestinal tract’, í Nature Biotechnology 22 (2004), pp. 204-209.)
Conclusions of the Newcastle Study:
Despite the obvious limitation that only a single GM Soya-containing meal was given to the subjects in this study, the following very pertinent conclusions with respect to environmental and health implications can be drawn from the results obtained.
Contrary to previously held views, the authors were “surprised” to find that up to 3.7% of intact (full-length) GM Soya gene DNA survived food processing, cooking and the acidic environment of the stomach and entered the small intestine in the ileostomy volunteers.
No GM gene material could be found in the stools of the normal subjects, suggesting that all GM material is degraded while passing through the large intestine. Therefore, it might be concluded that human excrement is unlikely to contaminate the environment with GM material provided the digestive process is normal. (Note: These findings may well not hold true if GM food is excreted by people with all or part of their large intestine missing or from people with illnesses associated with diarrhoea.)
Three of seven ileostomy subjects showed evidence of low levels of GM Soya gene transfer to bacteria in the small intestine. Interestingly, this was found to be the case before these volunteers had started the experiment and this did not increase after consumption of the meal containing GM Soya suggesting that that horizontal gene transfer to gut bacteria did not occur during the feeding experiment. (Note: It should be born in mind that only ONE GM Soya-containing meal was administered and therefore potential cumulative effects were not addressed).
“Nevertheless, on balance, the data presented in the paper support the conclusion that gene flow from transgenic plants to the gut microflora (bacteria) does occur. Furthermore, because transfer events seem to have occurred in three of the seven subjects examined, it may be that trans-kingdom gene transfers are not as rare as suggested … ”.
(John Heritage, ´The fate of transgenes in the human gut’, in Nature Biotechnology 22 (2004), pp. 170-172.)
Therefore, this study has clearly demonstrated that Horizontal Gene Transfer can occur and highlights the need for further testing for the safety of GM food in this area. This is particularly urgent since the transfer of antibiotic resistance genes (as well as other genes such as those for the Bacillus thuringiensis toxin pesticide) to gut bacteria can potentially severely compromise human and animal health.
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