Science - August 11, 2010

More toxic gluten in today's bread

The increase in the number of Coeliac patients in the last fifty years is partly caused by an increase in certain gluten proteins in modern wheat varieties. This is the contention of Hetty van den Broeck, who compared the presence of toxic gluten proteins in modern and in traditional wheat varieties.

The number of Coeliac patients within the Dutch population has increased. Coeliac is an auto-immune disease where particular glutens in grain products cause infections in the small intestine. Symptoms include head and stomach aches, diarrhoea, malnutrition and - in the case of children - growth disorders. 'About one percent of Dutch people are affected and 95 percent of them have not been diagnosed. Once you get it, it will not go away', says Van den Broeck. The only cure is to avoid consuming additional toxic glutens.
Controlled breeding
She compared the presence of two well-known gluten proteins which affect patients: Glia-a9 and Glia-a20, found in 36 modern wheat varieties of breeder Limagrain and fifty old country varieties of the Netherlands Centre for Genetic Resources (CGN). Among the modern varieties, only one was found to have a low concentration of these toxic gluten proteins, while the rest had high gluten concentrations. Among the traditional species, less pathogenic glutens were present. Her results were published at the end of July in the journal Theoretical and Applied Genetics.
Wheat breeding is not the only reason for the rise of Coeliac disease, suspects Van den Broeck. Wheat consumption increase and better disease identification methods also contribute to this rise. She advocates controlled breeding to cut down on the amount of toxic gluten in bread wheat. 'Nobody has ever paid any attention to gluten intolerance during wheat breeding; people are only concerned with yields and baking qualities.'
Persistent
Reducing the amount of gluten in bread wheat is far from simple. There are more than fifty different Glia-a proteins in an average wheat variety. Moreover, gluten proteins have an important role to play: they make wheat dough airy and are needed for it to rise. 'You can't just leave all of them out.' However, one protein is more toxic than another. 'Glia-a9 is a very persistent gluten protein, which more than fifty percent of Coeliac patients are sensitive to', adds Van den Broeck.
Medicines
Together with Limagrain, Wageningen researchers are trying to develop a new bread wheat by combining wheat varieties which have less toxic gluten proteins with older varieties. This breeding company participates in the Coeliac Disease Consortium where plant scientists work together with several university hospitals and companies. 'The university hospital Leiden and DSM search for medicines against gluten intolerance; we try to prevent gluten intolerance by developing safe wheat species', says the PhD student. She hopes to graduate in November in developing Coeliac-safe wheat. 'We know where to start, and the big question is: what will the breeding companies do about this?

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