In recent years, the number of people affected by celiac disease, wheat allergies, or gluten or wheat sensitivity has increased dramatically. Why this should be is not well understood. One theory is that modern wheat varieties contain more immunoreactive protein than those used in the past. Researchers at two German research institutions investigated this issue in detail.
Wheat grains contain about 70% starch. Proteins constitute 10 to 12% of wheat, and nearly 80% of that protein is gluten. Gluten is a compound mixture of two types of protein subgroups: gliadins and glutenins.
The researchers investigated the protein content of 60 preferred wheat varieties in use during the period between 1891 and 2010, making use of an extensive seed archive. They selected 5 leading wheat varieties for each decade over that 120-year period and cultivated the plants under the same geographical and climate conditions.
The results were that the modern wheat varieties actually contain slightly less protein than old ones. Gluten content itself has been essentially constant over the 120 years, although the proportion of gliadins (which are the prime suspect for causing undesired immune responses) was actually 18% lower while the proportion of glutenins was 25% higher.
Overall, they found no evidence that the immunoreactive potential of wheat has changed over the years as a result of the cultivation factors.
The researchers note that some of the other, less significant proteins in wheat have not been investigated with regard to their physiological effects, so there is more work to be done. But so far, the culprit for increasing wheat sensitivity has not been found.
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Photo, posted July 3, 2009, courtesy of Clare Black via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio.