Gluten is a protein that is present in wheat and other cereals, such as oats, barley, rye, emmer, kamut, spelt and triticale. In a genetically predisposed subject of any age, the ingestion of even small quantities of foods containing gluten triggers an immune response in the small intestine, causing a chronic inflammation. This in turn causes the eventual disappearance of the intestinal villi. This process is accompanied by a range of symptoms that vary from person to person. In a healthy individual, the intestinal wall is covered with villi and microvilli, the function of which is to increase the surface area of the intestine to aid the absorption of nutrients. In the celiac, however, these villi are greatly reduced and the mucous lining of the intestine is damaged. Because of the decrease in surface area, the absorption of nutrients such as protein, fats, carbohydrates, vitamins and minerals is inhibited, leading to malnutrition and loss of function. Gluten intolerance is one of the most common conditions worldwide. In countries with a population of primarily European origin (in Europe, North and South America and Australia), approximately one out of every 100 people is affected. A similar frequency has been reported in developing regions, such as North Africa, the Middle East and India, where large quantities of wheat are consumed.