Gluten is the major protein of wheat and other cereals (rye and barley); it is responsible for triggering celiac disease (CD) in genetically predisposed individuals. Until a few years ago, CD was the major (if not the only) well-known gluten-related disorder. However, in recent years, it has become clear that gluten proteins may activate different pathological mechanisms, leading to a wide spectrum of human diseases, including non-celiac gluten sensitivity (NCGS), gluten ataxia, neuro-psychiatric disorders, and many others. Conceptually, we have therefore moved from a Ptolemaic to a Copernican system, i.e., CD is no longer the "center of the universe", but is just one of the possible worlds of gluten intolerance. Many other gluten planets do indeed exist and deserve the attention of researchers and clinicians alike.
Although different gluten-related disorders show specific epidemiological, pathophysiological, and clinical aspects, these conditions share a trigger and treatment: the gluten-free diet. For a very long time, awareness of these disorders has been limited and, therefore, the epidemiology of gluten-related disorders is still a "work in progress". Current research strives to clarify the boundaries between these entities, their disease mechanisms, and how a proper diagnosis can be implemented.
