Gluten is a protein found in wheat, barley, rye and products made from these grains. Many foods that contain gluten provide fibre from whole grains and can be an excellent source of vitamins and minerals. But, for some people, gluten can cause severe digestive problems leading to nutrient malabsorption, anemia and many serious health problems. Celiac disease represents the most severe form of gluten intolerance and affects about 1% of the population. Another 5% of the population may have non-celiac gluten sensitivity (NCGS), which results in various gastrointestinal problems and other health issues.
Research has shown that the human leukocyte antigen (HLA) gene is the most important genetic predictor of gluten intolerance. Approximately 99% of people with celiac disease and 60% of those with NCGS have the DQ2 or DQ8 risk version of the HLA gene, compared to only 30% of the general population.