Genome-edited wheat to reduce cancer risk from bread

Scientists at Rothamsted Research in the south of England have used genome editing to reduce a cancer-causing compound commonly found in bread.

Acrylamide forms during bread baking and its presence is further increased when bread is toasted, and the darker the toast, the more of this carcinogenic compound it contains.

Now a team led by Rothamsted Research with colleagues from the University of Bristol have used the new technique of genome editing to develop a type of wheat that is less likely to produce acrylamide when baked.

According to project leader, Prof. Nigel Halford, the researchers are preparing an application to the UK government to run a field trial of this new wheat, starting in the autumn – the first such trial of genome-edited wheat to be carried out anywhere in Europe.

Prof. Halford said:

Acrylamide has been a very serious problem for food manufactures since being discovered in food in 2002. It causes cancer in rodents and is considered ‘probably carcinogenic’ for humans.

“It doesn’t just occur in toast and other wheat products, but many other foods that are fried, baked, roasted or toasted, including crisps and other snacks, chips, roast potatoes and coffee.”

The amount of acrylamide in bread is relatively low, but it increases many-times over when the bread is toasted.

The compounds that impart colour, flavour and aroma form by similar chemical pathways, so the darker and tastier the toast, the more acrylamide it is likely to contain. The same applies to other foods that are affected.

Low-asparagine

Sarah Raffan has just completed a PhD project to make and analyse the low-asparagine wheat and will be the lead researcher on the field trial.

“We’ve used genome editing to reduce the amount of the amino acid, asparagine, in the grain. It’s the asparagine that is converted to acrylamide during baking and toasting,” she said.

So a low-asparagine wheat should lead to lower levels of acrylamide, which is good news for anyone who likes their toast well done.

What is acrylamide?

Acrylamide is classed as a probable carcinogen by the International Agency for Research on Cancer.

In 2006, a UN Food and Agriculture Organisation (FAO)/World Health Organisation (WHO) Joint Expert Committee on Food Additives report stated that the potential cancer-causing effects of acrylamide in the diet were a concern.

A similar conclusion was arrived at by the EU’s Panel on Contaminants in the Food Chain (CONTAM) in 2015.

This led to the adoption of a European Commission regulation which states that “acrylamide in food potentially increases the risk of developing cancer for consumers in all age groups”.

These serious concerns have led Raffan, Halford and colleagues to attempt to produce low-asparagine wheat using genome editing.

Genome editing technology

The CRISPR/Cas9 genome editing technique leads to small changes in the DNA, such as the deletion or insertion of short sections of DNA, or changes to the DNA sequence, in this instance halting the function of a gene involved in the production of asparagine.

The sorts of changes to the wheat DNA are similar to those that occur naturally; the power of CRISPR/Cas9 is that the changes can be directed to a specific target gene.

Despite the differences between genome editing with CRISPR/Cas9 and genetic modification (GM), genome-edited plants are currently treated in the same way as GM under EU regulations, essentially blocking the use of a technology that is gaining official approval in many other parts of the world.

The expectation is that the current UK government consultation on this issue will lead to new legislation in the UK, allowing genome-edited food products, carefully regulated, to be available to consumers.