Aug 3, 2007

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Meat, milk and eggs free from GM feed?

EFSA: Transgenic DNA is digested the same way as other DNA

When animals are given genetically modified feed, are the foreign genes and proteins then found in food products derived from animals, like meat, milk and eggs? At the request of the European Commission, the European Food Safety Authority (EFSA) has published a statement on the current research status. Conclusion: No fragments of genes or proteins from GM plants have been found in edible animal products.

If animals are given genetically modified feed, the foreign genes and proteins cannot be detected in milk, meat or eggs.

In the debate about genetically modified food and feed, there have repeatedly been calls to label animal products like meat, milk and eggs as genetically modified if the animals have been fed on GM feed. Such products have until now been exempted from the labelling requirements. Against this background, the European Commission wanted EFSA to inform it whether, according to the latest research findings, fragments of the newly introduced genes or of the proteins they form are found in animal tissue or in milk and eggs. In its literature survey, EFSA comes to the following conclusions:

To date, no transgenic DNA has been found in organs or products from animals fed on GM plants. The fate of the newly inserted genes and the proteins they form has been investigated from feed production and silage, through digestion in the animals’ gastro-intestinal tract to the products. Researchers have also investigated whether the DNA and protein fragments that the animals take in are biologically active.

Feed production: Mechanical treatments of the feed plants have no influence on the DNA or proteins, but during silage and other processes, e.g. heating, they are broken down into small fragments.

Gastro-intestinal tract: DNA and proteins are also broken down further during the digestive process, including by special enzymes, which are part of natural defence mechanisms to protect against foreign DNA and proteins. EFSA stresses that plant-based food and feed naturally contains DNA and proteins that are subject to this degradation process. DNA introduced by means of genetic engineering does not differ in principle from other DNA.

Animal tissue and products: Because of the degradation of DNA and proteins during feed processing and during digestion, the probability of intact DNA or intact proteins being absorbed into the animals’ tissue or into animal products is very small. In studies with dairy cattle, growing calves, chickens and pigs, no DNA or proteins from GM feed have yet been found in animal tissue. Neither have any DNA fragments from GM feed been found in meat, milk or egg samples. By contrast, milk samples from animals that had been given conventional or organic feed were found to contain very small fragments of DNA that is sometimes introduced into plants using genetic engineering methods, but which originates in bacteria. This DNA was probably absorbed directly from the environment via the bacteria.

Biological functionality of absorbed DNA

The absorption of DNA or protein fragments by the body from the intestinal tract is a normal physiological process, according to EFSA. These fragments are so small and so thoroughly degraded that they are highly unlikely to be functional.

For the foreign DNA to become functional, it must be integrated into the genome. This kind of horizontal gene transfer from plant DNA into the animal genome is, however, extremely unlikely. In addition, the genetic information could not be expressed or activated there because certain control elements are missing.

In tests with mice that were fed with large quantities of genetically engineered DNA, no expression of this DNA was observed.

Currently, therefore, there are no indications that plant proteins could be formed in the tissue of animals fed on plants. No plant genes or parts of plant genes have ever been found in the human or animal genome.