Gluten-free is booming – it’s become a multi-billion dollar industry, supermarket aisles are crammed with products, with a number of high-profile celebrities endorsing their health impacts. But this is much more than a fad diet - doctors are seeing a growing number of patients who have serious problems with this protein, most commonly found in wheat products like bread and pasta. And, an increasing number of these patients do not have coeliac disease - for a long time the adverse reaction most commonly associated with wheat. So what’s going on? Graihagh Jackson hears about an emerging condition called non-coeliac gluten sensitivity, which could be affecting hundreds of millions of people worldwide, and meets the doctors fighting over how best to treat it. She asks why this condition is spreading so fast – could it be something to do with our modern lives and diets? And are wheat and gluten entirely to blame, or could there be dangers lurking in a whole range of other foods? (Picture: A woman's hand touching wheat in a field. Credit: Getty Images/BBC)