The recent spotlight on genetically modified foods and public attitudes towards them has revealed some fundamental misunderstandings about what genes are and what they do.

A recent UK public consultation (1) on developments in the bio-sciences found that while most people’s associations with the word “gene” were correct, some people were confused over the function of genes and some did not realize that they are consumed everyday as part of our normal diet.

However, genes are found in almost every cell of all plants and animals. They are the units of inheritance, composed of DNA, which are transmitted from parents to offspring during reproduction. It is the genes, typically several hundreds of thousands for a particular species, which carry the information needed by the cell to create the numerous proteins that the organism needs to develop, grow and multiply.

Consequently, every time we eat part of a plant or animal we ingest millions of genes and thus the DNA they are made of. They have no effect on us however, because they are either broken down as the food is digested or, if they are contained in resistant structures such as seeds, they pass unchanged through the body and are excreted. We have been consuming genes ever since we first evolved and there is no evidence that they can enter human cells from the food we eat. Even if they could, there is nothing to suggest that they would do us any harm.

There is no reason to believe things are any different for any genes in genetically modified (GM) food. Even though certain changes are introduced to the genes, the building blocks of the DNA are exactly the same. It should be clear however that in this context, we are talking about several different things. Firstly there are GM products that are eaten more or less unprocessed- for example a tomato in which a gene helping it to ripen has been inactivated to increase its shelf life. These products will contain intact, modified genes when they are consumed. As with non modified genes, they are broken down as the food is digested.

In processed foods such as tomato puree or soya flour, all genes (including any modified ones) are denatured and inactivated by the processing. Products extracted from plants such as sugars or oils may come from genetically modified plants, but they contain no genes and are identical to the same products extracted from unmodified plants. Finally there are foods whose production involves the use of enzymes derived from GM sources. A familiar example is “vegetarian” cheese, made with an enzyme (chymosin) from a genetically modified micro-organism, which is the same enzyme as the one of animal origin found in calf rennet. Here the modified genes never come into contact with the food.

Given these several different interpretations of GM food, confusion amongst the public is not surprising, especially when linked to mistaken ideas about what genes are and what they do. It also explains why 72% of those surveyed in the public consultation mentioned above said that they received too little information on these developments and how they are regulated.

References

The Public Consultation on Developments in the Biosciences. Commissioned by the Department of Trade and Industry from MORI.

FOOD TODAY 03/2000