Wheat, rye, and barley are universally acknowledged to contain the gluten proteins that trigger inflammation and damage to the small intestine in people with celiac disease. Gluten provokes the secretion of IgA-class autoantibodies which target tissue transglutaminase (tTG). These autoantibodies, called anti-tissue tranglutaminase (anti-tTG), are produced in the small-intestinal mucosa. Following ingestion of gluten, anti-tTG antibodies can be detected in the blood. A strict gluten-free diet is the only currently available therapeutic treatment for patients with celiac disease.
Whether oats cause the same type of reaction has been a controversial topic, with some experts saying yes and others claiming no.
Glutenfreeworks.com regularly receives reports from people with celiac disease who react with symptoms to so-called “gluten-free” oats. These oats are called gluten-free, because such oats are not contaminated with wheat, rye, or barley. However, as we explained in a previous article, the common oat grain contains avenin, which is gluten, albeit a less toxic form than the gluten found in wheat, rye or barley.
Just recently, a visitor related how badly she reacts to “gluten-free” oats.
“I don’t know what day I am into eating GF oats again, after not eating them for a while due to lack of money, and I can just say that right now, I feel like complete and utter crud. Its like eating wheat all over again. I feel nauseated, I get headaches, and not only that but within an hour and a half, I lose control of my bowels. Just. Like. Wheat. I can say now that I will no longer eat them, especially after reading this. Which really isn’t going to be fun since that is what I eat in the morning for breakfast.”
Oats can affect people with autism. A mother describes what happens when her son is exposed to gluten-free oats.
“We started a gluten free, casein free diet about four months ago. We have an eleven year old autistic son. We’ve discovered that in addition to gluten and casein, he’s sensitive to preservatives, additives, food dyes, soy and corn products, and sugars also. We’re in the process of going organic for the entire family. We recently tried Bobs red mill gluten free oats that are certified gf and grow only in oat fields. Omg what a problem the oats have caused for our son! He regressed tremendously as if we had never removed gluten in the first place! We noticed a reaction within 2-3 hours! Prior to being gluten free, et. al. he would exhibit aggressive behaviors such as hitting, scratching, spitting, throwing, yelling/growling, and banging walls. Now he’s calm and doesn’t exhibit those behaviors anymore! After giving him the gf oats, we noticed SOME negative change in behavior but didn’t think much of it, however after the third day of eating the gf oats he was back into full blown meltdown mode /aggressive behaviors. After a day and a half of stopping the gf oats, he is calmer, happier, and back to communicating well rather than impulsively aggressing!”
So, is there hope for oats?
Not all oats are equal in gluten content. In fact, there is wide range of variation of potential immunotoxicity of oat strains. While common oats may trigger inflammation, there seems to exist a least one strain that is truly “gluten-free.”
The quest for safe oats is reported in, “Molecular and Immunological Characterization of Gluten Proteins Isolated from Oat Cultivars That Differ in Toxicity for Celiac Disease.”
In order to elucidate the toxicity of the prolamins from oat varieties with low, medium, and high celiac disease toxicity, the avenin genes of these varieties were cloned and sequenced, and their expression quantified throughout the grain development. At the protein level, we have accomplished an exhaustive characterization and quantification of avenins by RP-HPLC and an analysis of immunogenicity of peptides present in prolamins of different oat cultivars.
Avenin sequences were classified into three different groups, which have homology with S-rich prolamins of Triticeae. Avenin proteins presented a lower proline content than that of wheat gliadin; this may contribute to the low toxicity shown by oat avenins. The expression of avenin genes throughout the development stages has shown a pattern similar to that of prolamins of wheat and barley. RP-HPLC chromatograms showed protein peaks in the alcohol-soluble and reduced-soluble fractions. Therefore, oat grains had both monomeric and polymeric avenins, termed in this paper gliadin- and glutenin-like avenins.
We found a direct correlation between the immunogenicity of the different oat varieties and the presence of the specific peptides with a higher/lower potential immunotoxicity. The specific peptides from the oat variety with the highest toxicity have shown a higher potential immunotoxicity. These results suggest that there is wide range of variation of potential immunotoxicity of oat cultivars that could be due to differences in the degree of immunogenicity in their sequences.
It is well-known that the proline content is positively correlated with the celiac toxicity of the storage proteins of various cereals –. The analysis of amino acids content of avenins reported throughout this article shows that avenins have a proline content that is lower than wheat gliadins and LMW glutenin subunits, and similar to HMW glutenin subunits. Therefore, the lower proline content of avenins could determine the lower celiac toxicity with respect to wheat prolamins.
Comparison of grains. Knowing the expression patterns of different storage proteins, as well as the features of their sequences, is important because they determine the characteristics of mature grain and possibly the potential immunogenicity for CD patients.
We have shown that the expression of avenin genes begins at 8 DPA, and reach the maximum level of expression between 20 DPA and 28 DPA. Thus expression begins at early stages of seed development and continues until late stages, when the peak is reached. Hence, oats follow an expression pattern similar to that in wheat and other cereals.
These results suggest that the differences in the protein sequences of different oat cultivars could explain why certain varieties of oats are toxic for CD patients and other not.
Source: Ana Real,1 Isabel Comino,1 Laura de Lorenzo,1,¤ Francisco Merchán,1 Javier Gil-Humanes,2 María J. Giménez,2 et al. Molecular and Immunological Characterization of Gluten Proteins Isolated from Oat Cultivars That Differ in Toxicity for Celiac Disease PLoS One. 2012; 7(12): e48365. Published online 2012 December 17