Cause
Coeliac disease is caused by an inflammatory reaction to gliadins and glutenins (gluten proteins) found in wheat and to similar proteins found in the crops of the tribe Triticeae (which includes other common grains such as barley and rye) and to the tribe Aveneae (oats). Wheat subspecies (such as spelt, durum, and Kamut) and wheat hybrids (such as triticale) also cause symptoms of coeliac disease.A small number of people with coeliac disease react to oats. Oat toxicity in coeliac people depends on the oat cultivar consumed because the prolamin genes, protein amino acid sequences, and the immunoreactivities of toxic prolamins are different in different oat varieties. Also, oats are frequently cross-contaminated with other grains containing gluten. The term "pure oats" refers to oats uncontaminated with other gluten-containing cereals. The long-term effects of pure oat consumption are still unclear, and further studies identifying the cultivars used are needed before making final recommendations on their inclusion in a gluten-free diet. Coeliac people who choose to consume oats need a more rigorous lifelong follow-up, possibly including periodic intestinal biopsies. Other grains
Other cereals such as corn, millet, sorghum, teff, rice, and wild rice are safe for people with coeliac disease to consume, as well as noncereals such as amaranth, quinoa, and buckwheat. Noncereal carbohydrate-rich foods such as potatoes and bananas do not contain gluten and do not trigger symptoms. Risk modifiers
There are various theories as to what determines whether a genetically susceptible individual will go on to develop coeliac disease.
Signs and symptoms
The classic symptoms of untreated coeliac disease include pale, loose, or greasy stools (steatorrhoea), and weight loss or failure to gain weight. Other common symptoms may be subtle or primarily occur in organs other than the bowel itself. It is also possible to have coeliac disease without any of the classic symptoms at all. This has been shown to comprise at least 43% of presentations in children. Further, many adults with subtle disease may only present with fatigue, anaemia or low bone mass. Many undiagnosed individuals who consider themselves asymptomatic are in fact not, but rather have become accustomed to living in a state of chronically compromised health. Indeed, after starting a gluten-free diet and subsequent improvement becomes evident, such individuals are often able to retrospectively recall and recognise prior symptoms of their untreated disease that they had mistakenly ignored. Gastrointestinal
Diarrhoea that is characteristic of coeliac disease is chronic, sometimes pale, of large volume, and abnormally foul in odor. Abdominal pain, cramping, bloating with abdominal distension (thought to be the result of fermentative production of bowel gas), and mouth ulcers may be present. As the bowel becomes more damaged, a degree of lactose intolerance may develop. Frequently, the symptoms are ascribed to irritable bowel syndrome (IBS), only later to be recognised as coeliac disease. In populations of people with symptoms of IBS, a diagnosis of coeliac disease can be made in about 3.3% of cases, or four times more likely than in general.