ist reis glutenfrei? — what are common causes?

Yes, rice is naturally gluten-free. Gluten is a protein found in wheat, rye, barley, and related grains – not in rice. However, processed rice products (e.g., rice flakes, rice cakes, ready meals) may be cross-contaminated with gluten-containing grains if produced in shared facilities. Some seasoned or flavored rice dishes may also contain gluten from additives. Common causes of gluten-related disorders include: celiac disease (an autoimmune condition), non-celiac gluten sensitivity (NCGS), and wheat allergy. In celiac disease, gluten triggers intestinal damage; NCGS causes similar symptoms without antibodies or villous atrophy. Wheat allergy is an IgE-mediated reaction. The evidence that rice is gluten-free is well-established (practice knowledge, dietary guidelines). The provided context does not contain specific studies on rice or gluten; this answer is based on general nutritional knowledge.