Are the right people on the gluten-free diet? A study recently published in the American Journal of Gastroenterology indicates that the answer to that question is no. Based on information gathered by the Centers for Disease Control (CDC), research reveals that while there are probably about 1.8 million Americans who have celiac disease and 1.6 million on the gluten-free diet, they are not the same people. Most people with celiac disease do not know they have it, and most people on the gluten-free diet do not have diagnosed celiac disease.
The study was funded by the National Institutes of Health and the CDC and analysis was led by the Mayo Clinic. How did the investigators find this information, and what does it mean?
Data is continually being collected by the CDC on the state of American health and nutrition in the National Health and Nutrition Examination Survey (NHANES). It is described as “…a program of studies designed to assess the health and nutritional status of adults and children in the United States. The survey is unique in that it combines interviews and physical examinations.”
Because this survey uses interviews, physical examinations and laboratory tests, it has given the best evidence of cases of undiagnosed celiac disease to date. Mobile examination centers go all over the country to gather information. Data for this study was collected between 2009 and 2010. All participants (at least 6 years of age) had blood samples tested for anti-tTG and if this test was positive, anti-endomysial antibodies. Participants were asked about whether or not they had been diagnosed with celiac disease by a doctor. For the purposes of this study, they were considered to have CD if they had a diagnosis from a doctor, or if both the blood tests were positive.
The percent of participants with CD was 0.71% in general and 1.01% for non-Hispanic whites. The majority did not know they had CD. 0.63% of the people were on a gluten-free diet, most of whom did not have CD.
The authors of the study used these numbers to estimate cases of CD in the United States as well as numbers of people on the gluten-free diet. The estimate of 1.8 million Americans with celiac disease is consistent with other estimates, but is based on the largest available amount of information. Only approximately 0.4 million of these people are diagnosed with celiac disease. The authors of the study believe that finding this number of patients is not good enough. In an official press release, co-author Joseph Murray, M.D., a Mayo Clinic gastroenterologist stated, “This provides proof that this disease is common in the United States. If you detect one person for every five or six (who have it), we aren’t doing a very good job detecting celiac disease.”
On the other side of the coin, 80% of the people who are on a gluten-free diet do not have diagnosed celiac disease and may not need to be on the diet. Because of its high cost and the difficulty of getting adequate nutrition without wheat and other gluten-containing grains, it is not generally recommended that people without either celiac disease or a definite wheat allergy eliminate gluten from their diets. People without either of these conditions do not experience any positive health effects from being on the gluten-free diet.
Researchers and clinicians are actively discussing and researching the best way to find people who do not know they have celiac disease. There are no current guidelines used to determine who to screen. Increase awareness of celiac disease and better blood tests are improving the chances that people with celiac disease will be correctly diagnosed.