The CeliKef project will examine whether the consumption of kefir affects celiac disease symptoms in individuals following a strict gluten-free diet. A randomized, controlled clinical trial with a crossover design will be conducted, in which participants will alternately consume kefir or continue their usual diet, with a washout period between the phases. Using validated questionnaires, we will monitor gastrointestinal symptoms, quality of life, and adherence to the gluten-free diet. Approximately 30 participants will be included in the study.