It took many years for scientists to discover that gluten sensitivity was a real condition. It was commonly written off by gastroenterologists until a few researchers decided to investigate what might be causing bloating, diarrhea and abdominal cramps in these patients.
Competing theories have emerged as the work has proceeded. Some scientists think that some substance in wheat, potentially gluten or possibly something else, is stimulating an immune reaction in gut cells that is leading to inflammation and the observed symptoms. Others, however, think that various kinds of carbohydrates, referred to collectively under the acronym FODMAPS, are to blame. These groups of molecules are fermentable - oligosaccharides, disaccharides, monosaccharides, and polyols, and can lead to bloating and other symptoms in the gut when they ferment there.
Gluten-free foods are generally only recommended for people that have been diagnosed with a wheat-related illness or allergy. There are clear markers that indicate those illnesses.
Some researchers believe that another condition exists, however, called nonceliac gluten sensitivity (NCGS). Self-reported symptoms are often used to diagnose this illness, however, and other scientists are still skeptical. Learn more from the video by Science.