Letter: Antibiotic fears

IT WAS tendentious of Marie Woolf to raise the hoary old question of antibiotic resistance genes in corn ("Modified corn on sale in the UK 'kills' life-saving antibiotics", 6 June).

Your stomach is highly acid. The source of antibiotic resistance genes in GM plants is from bacteria and the enzymes only survive in neutral, ie non-acid, conditions. Any bacterial enzyme that reaches your stomach in food is immediately inactivated and no longer functional. Furthermore, to acquire any of the enzyme from corn you would have to eat raw sweetcorn. All corn is processed in the UK. It is boiled, fried, heated, rolled, milled and extracted. No enzyme for any antibiotic resistance would survive more than a few seconds with these treatments. So to have any of the damaging effect on ingested antibiotic implied by Ms Woolf, you would have to munch raw sweetcorn at the same time as you are suffering the illnesses (carefully listed in the article to increase anxiety), and swallow your antibiotic (ampicillin) in the same mouthful. Because a mouthful of food takes about two seconds to reach your stomach, you could lose about 1 per cent of your dose of antibiotic. Given the variation in spoon size used for administering medicine, this loss would never be detectable.

ANTHONY TREWAVAS

Institute of Cell and Molecular Biology, Edinburgh