July 1, 2009 -- Celiac disease -- the digestive disorder treated by banning wheat and other grains containing gluten from the diet -- is four times more common in the U.S. today than it was 50 years ago, a study shows.
The study by Mayo Clinic researchers also linked undiagnosed and untreated celiac disease with an increased risk for earlier death.
Even with increased awareness about gluten-free diets and celiac, the disease remains underdiagnosed, experts say.
"We believe that only about 5% of people with celiac disease know they have it," University of Chicago Celiac Disease Center Director Stefano Guandalini, MD, tells WebMD. "Many of these people have no symptoms, but many do have symptoms that are not recognized for what they are."
Joseph A. Murray, MD, lead author of the study, says in a news release that celiac disease now affects about one in 100 people in the U.S.
Celiac Disease: Past and Present
Celiac disease is a digestive disorder in both children and adults. When people with celiac disease eat foods that contain gluten, an inflammatory reaction occurs that can damage the small intestine and inhibit the absorption of nutrients.
Gluten is present in all types of wheat, rye, and barley. Completely eliminating these foods from the diet for life is the only known treatment.
In the Mayo Clinic study, stored blood samples collected from healthy male army recruits between 1948 and 1954 were tested for the presence of a celiac-specific antibody.
The Mayo researchers also tested blood samples collected just a few years ago from men whose ages were either similar to the recruits at the time the samples were taken or at the time of the study.
They found that:
- The samples from the contemporary group of young people were 4.5 times more likely to have the celiac antibody than the samples drawn in the 1950s.
- The contemporary samples taken from older men whose ages matched the current ages of the recruits were four times as likely to have the antibody.
- During 45 years of follow-up, undiagnosed celiac disease was associated with a fourfold increased risk of death.
In a 2003 study, Murray and colleagues found that celiac disease was being diagnosed at a rate that was nine times higher than just a decade before.
One aim of the new study was to find out if this represented a real increase in incidence or simply better awareness of the disease and better ways of diagnosing it.
"Celiac disease is unusual, but it's no longer rare," Murray says. "Something has changed in our environment to make it much more common."
Celiac Disease and the Hygiene Hypothesis
One theory is that celiac disease is on the rise because we are exposed to fewer germs than in the past, says Murray.
The so-called "hygiene hypothesis" suggests that this diminished exposure has increased our susceptibility to certain diseases.
Murray tells WebMD that changes in the way wheat is grown and processed may also play a role.
"These are just theories," he says. "We really can't say what the environmental influences are."
"The good news about celiac, which makes it unique among autoimmune disorders, is that it is completely reversible once you begin the gluten-free diet," Guandalini says. "The majority of patients have very rapid responses, especially children."