Coeliac disease is an immune condition in which gluten damages the small intestine and affects nutrient absorption. NHS guidance identifies wheat, barley and rye as sources; symptoms may include bloating, diarrhoea and fatigue. After diagnosis, avoiding gluten is not simply a preference for reducing bloating: it helps prevent complications even when symptoms are mild. A balanced varied diet still matters beyond buying products labelled gluten-free. Fatigue or abdominal discomfort alone cannot establish coeliac disease. Discuss testing, especially with a family history, rather than diagnosing yourself from temporary improvement after changing foods.