Sir: Joanna Blythman is wrong to suggest GM technology is being used in food and that there is no issue with supply with non-GM soya from Brazil (‘Retailers talk tosh on GM feed,’ 18 May).

Poultry fed on feed containing GM ingredients does not produce GM meat or eggs. In 2007, EFSA established that recombinant DNA from GM plants used in feed does not end up in the final milk, meat or eggs.

It is a fact that the amount of commercial non-GM soya being grown in Brazil is declining, while the amount of GM soya has increased from 58% in 2008/09 to 89% in 2012/13 as more Brazilian farmers move to more sustainable GM varieties.

The worldwide growth in demand for soya has stimulated production. But the Brazilian infrastructure has not expanded at the same rate. This has caused problems keeping supply chains for GM and non-GM soya separate. Two suppliers of non-GM into the UK stopped earlier this year as they could not guarantee the integrity of these loads.

Those more informed than Ms Blythman on soya knew it would be difficult to guarantee the delivery of non-GM soya for this reason and because of loading difficulties at Brazilian ports. Earlier this year, shippers were struggling to get any soya out of Brazil, let alone more ‘niche’ non-GM varieties.

This is not about the retailers ignoring consumers, it’s about being honest and transparent about the realities. The NFU maintains that politics and emotion should not be driving this debate, science should.

Kelly Watson, NFU chief poultry adviser