Intended for healthcare professionals

Clinical Review

Genetically modified foods

BMJ 1999; 318 doi: (Published 27 February 1999) Cite this as: BMJ 1999;318:581
  1. Leighton Jones, publications manager. (
  1. Campden and Chorleywood Food Research Association (CCFRA), Chipping Campden GL55 6LD

    Editorial by Dixon and p 611)

    The use of genetic modification in food production is proving contentious and attracting much media coverage. Despite this, it can be difficult for anyone not directly involved to know how to obtain hard facts. Genetically modified foods raise many issues—scientific, technological, environmental, social, ethical, economic, and political—too many to cover here. This article therefore paints a broad picture of genetically modified foods and provides a lead to sources of information by addressing three specific points:

    • What is genetic modification and how does it relate to food production?

    • What are the current and future applications?

    • What concerns do genetically modified foods raise?

    Manipulating DNA

    Genes change every day by natural mutation and recombination, creating new biological variations. Humans have been exploiting this for centuries—shuffling genes in increasingly systematic ways and using extensive crossing and artificial selection—to create many combinations that would never otherwise have occurred. Just about everything we eat is derived from livestock, crops, and micro-organisms bred specifically to provide food. Humans have also redistributed genes geographically: the soybean is native to Asia but is now grown throughout the Americas, and the potato, native to the American continent, is grown throughout the temperate world. DNA has never been “static,” neither naturally nor at the hand of people.

    Genetic modification is an extension of this. However, unlike conventional breeding, in which new assortments of genes are created more or less at random, it allows specific genes to be identified, isolated, copied, and introduced into other organisms in much more direct and controlled ways (see boxes). The most obvious difference from conventional breeding is that genetic modification allows us to transfer genes between species. For example, the gene for bovine chymosin has been transferred to industrial micro-organisms—Kluyveromyces lactis (a yeast), Aspergillus niger var awamori (a fungus), …

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