ngin - Norfolk Genetic Information Network

15 March 2003


Below are comments from Dr Michael Antonio, a senior lecturer in molecular genetics at King's College Medical School, London, on research conducted at the University of Newcastle upon Tyne showing for the first time that genes inserted in GM crops are finding their way into human gut bacteria. GM crops have antibiotic-resistant marker genes inserted in them, and there are fears that if material from these marker genes passes into humans, people's ability to fight infections may be reduced.

The research was commissioned by the UK Government, as part of a project entitled "Evaluating the risks associated with using GMOs in human foods." It was published by the UK's Food Standards Agency (FSA) who  released the research, involving feeding volunteers with a burger and a milkshake containing GM soya, with a press release saying it "showed in real-life conditions with human volunteers, no GM material survived the passage through the entire human digestive tract... the research concluded that the likelihood of functioning DNA being taken up by bacteria in the human or animal gut is extremely low".

But although the scientists at the University of Newcastle did not find DNA from GM food in the faeces of normal volunteers they had found that bacteria in the human gut can take up GM DNA. They found transgenic DNA had survived in the wastes from seven subjects with ileostomy bags and that for one in three of the seven, the gut bacteria had taken up the DNA. In a separate experiment on colonies of intestinal cells, the Newcastle team showed that loops of GM DNA called plasmids can be taken up directly, but only by one gut cell in 3000.

The design of the experiment has been criticised as being biased against finding positive results - for instance, using a probe for GM DNA that detects only 5% of the entire length, and not monitoring the blood of the volunteers. In experiments dating back to the early 1990s, German scientists have found that transgenic DNA fed to mice can pass through the gut and also through the gut wall into the blood stream, ending up in blood cells, liver and spleen cells.


Newcastle Feeding Trial - Comments by Dr Michael Antoniou

The Newcastle study shows that intact gene DNA survives the acidic environment of the stomach and enters the small intestine. Once in the small intestine, there was also evidence found that intact (and functional) GM gene DNA enters bacteria. Yes, they did not find it in the faeces of normal volunteers suggesting that it ultimately gets degraded in the large bowel.

However, the major individual health problem is not what "comes out at the other end" but what goes on inside the gut! So the risk of a health problem arising from the transfer of GM genes such as antibiotic resistance and Bt toxin to gut bacteria still stands.

Also, please note that the paper quoted in the response to Arpad Pusztai is in "human intestinal simulations"; i.e. test tube experiments and NOT real people at all! Interesting but hardly physiological!

We should also not stop reminding people that the Newcastle study entailed only ONE GM soy containing meal, which can hardly be called statistically significant but which yet showed up these very worrying findings all of which were hotly denied as possible in the past.

Finally, the Newcastle study failed to carry out experiments with simulated diarrhoea conditions (e.g. administering a laxative) to assess whether bacteria containing GM genes would then be present in the faeces and released into the environment to pose a yet further problem for us all by for example spreading antibiotic resistant pathogenic bacteria into the environment!

Follow-up work to this initial investigation clearly needs to be initiated involving the monitoring of a proper large cohort of people over a prolonged period of time (at least 6 months) where GM foods form a dominant component (>50%)  of their diet, including foods containing antibiotic resistance marker genes (which the GM soya used in the Newcastle study did not contain). Simulated diarrhoea trials (e.g. administering a laxative) must also be carried out.

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