Molecular and clinical approaches to evaluate the suitability of oat varieties for gluten-free diet

Celiac disease (CD) is an immune-mediate disorder, triggered in genetically susceptible individuals by a class of cereal proteins, called prolamins. Among them, the most toxic protein is wheat gliadin (part of gluten), but also rye secalin and barley ordeine show similar toxicity in celiac subjects. The current treatment for patients with CD is the exclusion of any food products containing toxic prolamins, but a long-term gluten-free diet (GFD) could cause some nutritional deficiencies. Among cereals, oat has been recently allowed in EU as a gluten-free ingredient, even though its inclusion in CD diet is still a matter of debate. Oat is rich in fibers, vitamins and minerals and its use could improve the nutritional value and increase the palatability of the GFD. Due to the concerns described above, a research on oat was promoted in order to evaluate the tolerance of different varieties by celiac patients. The study included more then 20 oat varieties, which were screened for their immunoreactivity using biochemical and immunochemical approaches. The first part of research allowed the selection of two "new" suitable oat varieties: Irina and Potenza. Oat extracts were assayed, as such and after gastrointestinal digestion, in some in vitro tests mimicking the cellular toxicity in celiac subjects. At molecular and cellular level, Irina and Potenza showed no toxic activity, but this could not be generalized to all oat varieties. The selected varieties were included in a double-blind, placebo-controlled multicenter study, performed in a group of Italian children, for evaluating the safety of gluten-free oat-based products. During the study different clinical parameters have been evaluated, including serological and cytological CD markers (IgA antibodies). An ELISA method was set up and optimized in our laboratory to measure the level of anti-gliadin and anti-avenin (the oat prolamin) IgA antibody in children sera, since there was a doubt about a possible role of oat in inducing a new auto-immune antigenic response. Although the study is still blinded the preliminary results suggest the safety of gluten-free oat-based products in the diet of CD patients, when oat is previously checked for its immunoreactivity in suitable in vitro models and in clinical trials.