A Reduced-Gliadin Wheat Bread Suitable for Celiacs?

If you have celiac disease, you almost certainly miss bread and other specific foods that have been hard to replace with ingredients that don’t contain wheat gluten. Scientists do know that the parts of wheat gluten called gliadins trigger reactions in people with celiac disease. There are specific pieces of the gliadins that cause trouble, and the amino acid sequence of these pieces in also known. If it were possible to grow wheat without these pieces, it would theoretically be safe for people with celiac disease.

The problem with gluten-free food is that gluten and its gliadins are actually responsible for many of the properties of wheat (as well as a number of other grains) that make it behave in the way it does. Wheat flour has specific attributes that make the texture and taste of bread people are used to, and this has been difficult to replace. In a recently published article, agricultural scientists from Italy explained that wheat’s ability to make bread and other food items “…is a consequence of the unique viscoelastic properties of wheat dough, which allow the entrapment of CO2 during fermentation, enabling the preparation of leavened breads and other baked products.”

Both rice and corn flour can be used to make gluten-free bread and other items, but they are disappointing in terms of texture and flavor. Flour from ground nuts has also been made. Cooks and nutritionists have tried mixing various groups of ingredients in order to make pasta, bread, and other staples traditionally made with wheat. These do not replace the real thing, although there are now so many people and companies working on this that gluten-free foods are much improved over what was available in the past.

For these reasons, food scientists are trying to find a way to make gliadin-free or reduced-gliadin wheat that can still make bread. People with celiac disease are only able to eat completely gluten-free foods, but reducing the gliadin content is a step in the right direction. Since there are also drugs being researched that help more completely break down glutens and gliadins in the intestine or keep them out of the circulation, it could be possible in the future for those with CD to eat reduced-gliadin wheat along with one of the drugs to eliminate whatever gliadins remain. For those with non-celiac gluten sensitivity (NCGS), reducing the gliadin content might be enough to eliminate symptoms.

The agricultural scientists recently published a study detailing their success in making good bread from specific kinds of reduced-gliadin wheat. The wheat produced was baked into bread that was very similar in quality to regular wheat bread. Their research included analysis of the taste, texture and properties of bread made from their wheat, compared to normal wheat and rice flour. Replicating the important properties of wheat as closely as possible was their goal.

The scientists used grains with low gliadin content that have already been developed. They originated from strains of wheat that exist naturally, so-called wild wheat. One is a line from Triticum strains of wheat that has a natural variability in its gluten/gliadin content. Continuing to grow and breed strains derived from this wheat has led to a strain with even lower gliadin content. Additionally, scientists used a specific method to delete certain gene sequences which code for gliadins in other wheat strains. This entailed using RNA (which sends messages to genes) to “down-regulate” genes that make gliadins in wheat, yielding another low-gliadin strain. It has taken many years to develop these wheat strains, but at this point the researchers believe that they have two kinds of low-gliadin wheat that has not lost all of its viscoelastic properties and can still be baked into satisfying bread.

They used the two described strains of wheat in their original forms (wild type) and their reduced-gliadin forms plus standard rice flour to bake loaves of bread. They analyzed the properties of the flour from these wheat strains with both scientific tests as well as taste tests. Taste tests are important, because the goal is to find an acceptable substitute for normal wheat that people with CD will enjoy, and this cannot be proven by strictly scientific methods. Trained “assessors” were used to sample the breads.

Analysis included:

• Physical characteristics of baked bread, including appearance, volume, and shape.
• Taste of the bread by 11 trained bread assessors, who evaluated the breads’ appearance,aroma, flavor, and overall acceptability.
• Nutritional content, specifically amino acid content.
• Microstructure of the bread and bread crumbs viewed by electron microscopes.
• Total gluten and gliadin content.

Both of the reduced-gliadin wheats produced breads that were acceptable to the assessors and similar in many ways to the breads from the wild strains. Both were considered much better than bread from the rice flour. Measurable physical characteristics corresponded well with the assessors’ results.

The researchers also discovered that the lysine content of the reduced-gliadin flour was higher than that of the wild flour. Lysine is an essential amino acid which the human body cannot make. Its presence in the modified wheat indicates good nutritional content.

The amount of gliadin or gluten that can be consumed safely by people with celiac disease has been estimated by other researchers. It is believed that 50 mg a day is the most gluten that people with celiac disease can safely eat over a prolonged period of time. This would correspond to 43.6 grams to 66.9 grams a day of the two reduced-gliadin breads, some 30 times more than the original wheat bread. The investigators also produced data indicating that the gliadin still present in the bread causes less reaction than what is in wild wheat, so that even more might be safe to eat. However, all of this is speculative.

It is very good to know that there is a way to develop bread lower in gluten that still tastes like bread. How safe it is still needs to be studied. It seems possible that reduced-gliadin wheat along with one of the drugs in development might be a safe combination for people with celiac disease that would allow them to eat food that is more satisfying than some of the currently available choices.

[hr]Reference
Gil-Humanes J, Pisto´n F, Altamirano-Fortoul R, Real A, Comino I, et al. (2014) Reduced-Gliadin Wheat Bread: An Alternative to the Gluten-Free Diet for Consumers Suffering Gluten-Related Pathologies. PLoS ONE 9(3): e90898. doi:10.1371/journal.pone.0090898.