Some science behind the scenes
Coeliac disease is a disorder of the small intestine that occurs in genetically predisposed people of all ages from middle infancy onward.
Symptoms include pain and discomfort in the digestive tract, chronic constipation and diarrhoea, failure to thrive (in children), anaemia, headaches, bloating, vitamin deficiency and fatigue.
The condition is thought to affect between 1 in 100 people in the UK. Coeliac disease is superficially caused by a reaction to gliadin, a prolamin (gluten protein) found in wheat and other common grains such as barley and rye. Upon exposure to gliadin, the immune system cross-reacts with the small-bowel tissue, causing an inflammatory reaction. That leads to a truncating of the villi lining the small intestine (called villous atrophy). This interferes with the absorption of nutrients. There are various theories as to what determines whether a susceptible individual will go on to develop coeliac disease.
What appears to have actually happened however, is that intestinal flora and enzymes which are there to handle gliadin have been destroyed at some stage and as such the Intestine can no longer process the protein.
There are a number of pathogens implicated in the destruction. Major theories so far include infection by rotavirus or human intestinal adenovirus, but there are also links with pesticides and other toxins. Pharmaceuticals, particularly antibiotics are also implicated. A growing list of pharmaceuticals appear to damage the Intestine enough to cause the disease see this ehealthme LINK.
Treatments for acne, anti-depressants, anti-psychotics, osteoporosis treatments, pain killers and NSAIDs including aspirin, asthma and COPD medication, the benzodiazepines, insomnia treatments, calcium channel blockers, anti-inflammatory drugs, beta blockers, ACE inhibitors, Statins and MS treatments are all implicated.
The section on Intestine disease provides a more complete list of all the possible causes of food allergies in general when related to the intestine.
Schematic of the Marsh classification of upper jejunal pathology in coeliac disease