How will you take your medicine? Fried or boiled?

Two American companies have separately devised ways to make hens produce useful pharmaceutical chemicals in their eggs. Once distilled from the genetically modified egg whites, the proteins could be used for straightforward medical treatment.

Two American companies have separately devised ways to make hens produce useful pharmaceutical chemicals in their eggs. Once distilled from the genetically modified egg whites, the proteins could be used for straightforward medical treatment.

GeneWorks, in Ann Arbor, Michigan, already has a flock of between 50 and 60 GM chickens, New Scientist magazine reported yesterday. Some of the fowl have a gene that makes them secrete a human growth factor in the whites of their eggs; others produce a human antibody for fighting infectious diseases.

AviGenics, of Athens, Georgia, says that it has GM cocks siring chicks that produce human interferon, which fights cancer, in their eggs.

The potential for both companies is huge. Each egg contains about 100mg of the human protein, and a normal hen can produce 200 eggs a year. Multiplied across a flock, GM technology could produce huge "pharms" in which chickens are a principal source of drugs.

Sadly, though, the hope of a GM egg breakfast to cure your ills is unfounded: cooking would literally scramble the amino acids that make up the drugs, rendering them useless. And eating the eggs raw would not guarantee the dose received.

Researchers at PPL Therapeutics, the company that has a flock of GM sheep whose milk contains a drug to treat cystic fibrosis, predicted that it could take at least five years for the drugs from the GM chickens to reach patients.

And other scientists expressed disappointment that the technology used to produce the GM eggs had not been published in scientific literature so that other researchers could examine it for flaws.