The inclusion of genetically modified (GM) plants in the human diet has raised concerns about the possible transfer of transgenes from GM plants to intestinal microflora and enterocytes. But the persistence in the human gut of DNA from dietary GM plants remained an unexplored land.
Scientists led by Harry Gilbert at the university of Newcastle in the UK set out to study the survival of the transgene epsps from GM soya in the small intestine of human ileostomists - people with a colostomy bag.
They found that DNA can survive to the small intestine, and that low frequency gene transfer to the gut microflora of gene fragments may have occurred.
However, the study showed that whole genes were not present in the microflora, and that it was unlikely that there was DNA transfer to the intestinal epithelial cells, and risk to human health was thought to be "highly unlikely".
Reporting their findings in in the 18 January issue of Nature Biotechnology, the scientists write that while the plant DNA was found in the small intestine of ileostomists there was no survival of the DNA in the large intestine of subjects who had not undergone such surgery.
According to the scientists, it appeared that low frequency gene transfer from ingested DNA to the gut microflora had occurred already in 3 of the 7 ileostomists prior to the trial.
The authors of the paper say "it is highly unlikely that the gene transfer events seen in this study would alter gastrointestinal function or pose a risk to human health. Nevertheless, the observed survival of transgenic DNA from a GM plant during passage through the small intestine should be considered in future safety assessments of GM foods."
The paper, "Assessing the survival of transgenic plant DNA in the human gastrointestinal tract," by Trudy Netherwood, Susana M Martín-Orúe, Anthony G O'Donnell, Sally Gockling, Julia Graham, John C Mathers & Harry J Gilbert appears in Nature Biotechnology, 18 January 2004, doi:10.1038/nbt934.