Researchers from the Mayo Clinic examined blood tests from a nationally representative sample of nearly 8,000 individuals and found markers for celiac disease in 35 participants, or 0.71% of the total sample. They then combined these results with interviews from the National Health and Nutrition Examination Survey (NHANES). Twenty-nine of the 35 subjects suspected to have celiac disease previously had not been diagnosed with the disorder.
"Virtually all the individuals we found were non-Hispanic Caucasians," said co-author of the study Alberto Rubio-Tapia, a Mayo Clinic gastroenterologist. He added that previous research in Mexico has suggested celiac disease there could be just as common as it is in the United States.
"So that is something we don't fully understand," he said.
Celiac disease is an autoimmune disorder with symptoms triggered by consumption of gluten, the protein in wheat, barley, rye and spelt. Currently the only available treatment is complete dietary avoidance of gluten.
The prevalence of those on a gluten-free diet was highest among female adults, but not among non-Hispanic whites – although non-Hispanic whites accounted for 29 of the 35 cases of suspected celiac disease.
About 80% of those on gluten-free diets had not been diagnosed with the disorder.
"There are a lot of people on a gluten-free diet, and it's not clear what the medical need for that is," said study co-author Joseph Murray, also a Mayo Clinic gastroenterologist. "It is important if someone thinks they might have celiac disease that they be tested first before they go on the diet."
The market for gluten-free products has grown faster than expected in recent years, driven by increased diagnosis of celiac disease, a growing market of individuals with abdominal or intestinal symptoms that they manage with a gluten-free diet, and those who choose gluten-free products because they believe them to be healthier. Market research organization Packaged Facts valued the market at $2.64bn in 2010 – a compound annual growth rate (CAGR) of 30% from 2006 to 2010.
Extrapolating their data to the US population as a whole, the researchers suggested that celiac disease could affect about 1 in every 141 people in the United States, but about 1 in 100 non-Hispanic whites. Overall, their results suggest a similar prevalence of celiac disease in the US as in Europe.
The researchers acknowledged that their study was limited by their use of blood tests, rather than intestinal biopsy, the accepted method for diagnosing celiac disease. They said that performing an invasive procedure such as intestinal biopsy has historically led to high non-participation rates, making it unfeasible for gathering data from large groups of individuals.
Dietitians previously have suggested that many celiac diets are low in nutrients, particularly fiber and iron, as manufacturers have often relied on combinations of rice flour, corn starch, potato starch and tapioca starch for gluten-free formulations. However, manufacturers have increasingly moved beyond these relatively nutrient-poor ingredients toward other, more nutrient-rich ingredients, such as mesquite flour, millet, nut flours, pulse flours, sorghum, soy, and teff.
Meanwhile, Packaged Facts predicts that the market for gluten free foods will continue to grow over the next several years, albeit at a slower rate, and now projects the US market for gluten-free foods to approach $5.5bn by 2015.
Source: The American Journal of Gastroenterology
“The Prevalence of Celiac Disease in the United States”
Authors: Alberto Rubio-Tapia, Jonas F. Ludvigsson, Tricia L. Brantner, Joseph A. Murray, and James E. Everhart