The mystery of coeliac disease has been cracked by scientists, paving the way for treatments for the condition that blights the lives of millions of people.
The intolerance to gluten, the main protein in wheat, rye and barley, causes the immune system to attack the gut.
Now British and Australian scientists have pinpointed why the protein can be so toxic.
Wheat based products such as bread trigger coeliac disease
They gave 200 patients bread, rye muffins or boiled barley to eat and, tested their blood six days later to see how their immune systems responded.
This showed that 90 of the 2,700 protein fragments that make up gluten had been treated as toxic by their bodies.
But three were particularly bad, the journal Science Translational Medicine reported.
Melbourne-based researcher Dr Bob Anderson said: 'These three components account for the majority of the immune response to gluten.'
Adding that it had been 60 years since gluten was shown to cause coeliac disease, he said: 'The holy grail in coeliac disease research has been to identify the toxic peptide components of gluten; and that's what we've done.'
Melbourne biotech company Nexpep has created a jab to desensitise people with coeliac disease to gluten.
Up to one in 100 Britons suffers from the disease. Symptoms include diarrhoea and cramps and it can lead to malnutrition and osteoporosis.