By Clare Stanfield
For the last decade or so, wheat has been the target of many health claims. Several theories have come forward, declaring that modern wheat is fundamentally different from its ancient counterparts and that this has led to a huge rise in celiac disease, among other things.
That got Dr. Ravi Chibbar thinking. “The way it started was about seven or so years ago, all of a sudden there was this idea in the popular press that wheat was bad and this was somehow due to genetic improvements,” he says.
Chibbar, a professor in the Department of Plant Sciences at the University of Saskatchewan, is a biochemist and molecular biologist who studies the genetic determinants of grain quality. He was struck by how many of the people making claims about modern wheat had no experience in, or knowledge of, genetic improvement in general, and wheat improvement in particular.
So he developed an idea for a research project that would take a comprehensive look at wheat gluten proteins to see if and how they have changed over time and what impact that has had on the growing incidence of celiac. With funding from a number of organizations, including Sask Wheat, Chibbar and his colleagues set to work.
“We had access to a set of 37 historical CWRS wheat varieties going back to Red Fife,” he says, adding that this cultivar was introduced in Western Canada in the 1860s.The newest cultivar in the set is from 2007, and Chibbar says that the entire set includes representative cultivars from all decades in between, representing major wheat improvements made over this time span.
One of the first things the team discovered was that the grain protein concentration is similar in newer cultivars of wheat when compared to older varieties, rising only one per cent over the last 100 years. “So if there are no changes in the quantity, what about the quality of proteins?” asks Chibbar. The next step, therefore, was to study if there was a definitive link between wheat gluten quality and celiac disease.
Gluten is composed of two major groups of polypeptides: gliadins and glutenins. Celiac disease is an autoimmune reaction to gluten, specifically gliadin, and affects roughly one percent of people worldwide. Working with a gastroenterologist from the University of Alberta, Chibbar was able to obtain blood serum from 13 known celiac patients with varying levels of disease severity, as well as serum from one patient with no celiac disease to use as a control.
Then, using a process called gel electrophoresis, researchers separated glutenin and gliadin proteins from all 37 study cultivars. “The separated polypeptides were transferred to nitrocellulose membranes that were treated with patient serum to identify the antibodies that reacted with wheat grain polypeptides,” says Chibbar. Essentially, the process allowed him to identify wheat proteins that reacted to antibodies from celiac patients.
Researchers wanted to see if this reaction differed depending on the cultivar. Specifically, they wanted to know if the peptides in older wheats were less reactive than those in newer ones. They found that there was no significant difference. Chibbar says that glutenin and gliadin composition does differ between cultivars, but that this diversity is not time-specific. In other words, someone with celiac can have a response to ancient as well as modern wheat cultivars.
“Indications so far are that wheat improvement has not been responsible for the increase in celiac reactive polypeptides,” says Chibbar. But there is still much work to be done to figure out exactly what is happening. “We want to find how wheat proteins changed over time, and if that change has any bearing on the severity of celiac or the expansion of celiac.”
Health issues like celiac are complex and solutions not easy or straightforward. Chibbar hopes that, as he and his team analyze the data they’ve amassed, this research will provide some much needed scientific evidence around the actual role wheat proteins have played in the increased prevalence of celiac disease and how wheat improvement can even be a part of the solution to reduce it. “Wheat is a part of the staple diet around the world and everyone should be able to enjoy it without reservations,” says Chibbar.
“Doing the work is the easy part,” he laughs. “Coming to conclusions is much more challenging. That’s the stage we’re at now.”Source : saskwheat.ca