UK coeliac disease diagnoses 'up fourfold' over 20 years
The number of people diagnosed in the UK with coeliac disease has increased fourfold between 1990 and 2011, a study suggests.
The autoimmune disease, triggered by a reaction to gluten - found in wheat, barley and rye - can cause severe symptoms.
It is treated by following a lifelong gluten-free diet.
Experts say they believe the increase is due to better diagnosis, rather than more people developing the condition.
Left untreated, coeliac disease can lead to infertility, osteoporosis and bowel cancer.
The University of Nottingham research, published in the American Journal of Gastroenterology and funded by the patient groups Coeliac UK and CORE, looked at the GP data from 1990 to 2011 to see how many cases had been diagnosed.
It found the rate increased from 5.2 per 100,000 in 1990 to 19.1 per 100,000 in 2011.
Previous studies have suggested around 1% of the population would test positive for the condition - but the data from this study suggests only 0.25% are diagnosed.
Coeliac UK say this means many are unaware they have the condition.
Sarah Sleet, the charity's chief executive, said: "Of course, increasing numbers with a diagnosis is good news and will inevitably mean there will be an increased demand for gluten-free products in supermarkets.
"But the three-quarters undiagnosed is around 500,000 people - a shocking statistic that needs urgent action."
Diagnosis rates vary by area, with a higher incidence in more affluent places.
The researchers suggest this is probably down to differences in diagnostic rates and not down to more people actually having the condition in particular areas.
Joe West at the University of Nottingham led the study. He said: "The study shows something has obviously changed in the last two decades and what I think is more likely is that we've got better at diagnosing coeliac disease.
"We now have better, and more available, tests."
Dr Anthon Emmanuel, consultant gastroenterologist at UCL, said: "This [increase] is a diagnostic phenomenon, not an incidence phenomenon. It is exactly what we had anticipated."
He said testing for the disease had got much easier in recent years, and was now a simple blood test rather than the "palaver" of the more intrusive test used previously.
Sarah Sleet added: "We were hoping diagnosis rates had gone up, as they were appallingly low.
"There has been increased public awareness in the past 20 years, and we have been working with professionals to develop frontline testing which is easier to use and cheap."