Time Trends in the Prevalence of Celiac Disease and Gluten-Free Diet in the US Population: Results From the National Health and Nutrition Examination Surveys 2009-2014

Previous studies^1,2 have reported that the prevalence of celiac disease in the United States is increasing, although these studies were limited to narrow populations and were not nationally representative. At the same time, there is a current popular trend of people following gluten-free diets,³ beyond what would be expected if it were solely attributable to the increasing prevalence of celiac disease. It may be in part because of a public belief that the diet is healthier. The purpose of this study was to examine the current trends in the prevalence of celiac disease and adherence to a gluten-free diet, including people without celiac disease, using nationally representative data from the National Health and Nutrition Examination Surveys (NHANESs) 2009-2014.

From January 1, 2009, through December 31, 2014, there were 22 278 persons 6 years or older who participated in NHANESs who underwent serologic testing for celiac disease for whom information about prior diagnosis of celiac disease and use of gluten-free diet was obtained by direct interview. Celiac disease was defined as having either double-positive serologic test results on IgA tissue transglutaminase and endomysial antibody or a reported diagnosis by a health care professional coupled with being on a gluten-free diet. People on a gluten-free diet without celiac disease were identified as those adherent to a gluten-free diet without serologic test results positive for celiac disease or a physician-given diagnosis. Trends in the prevalence of celiac disease and in adherence to a gluten-free diet among people without celiac disease were estimated in the total population, as well as by age, sex, and race. Appropriate published weights and a direct standardization method were used to estimate prevalence. All analyses were conducted using R software, version 3.2.2 (R Foundation for Statistical Computing). The NHANES study was approved by the National Center for Health Statistics Research Ethics Review Board, and all participants provided written informed consent. This analysis per se was deemed exempt by the Rutgers New Jersey Medical School Institutional Review Board because the data set used in the analysis was completely deidentified.

Overall, 106 (0.69%; 95% CI, 0.53%-0.84%) and 213 (1.08%; 95% CI, 0.80%-1.35%) participants were identified as having a diagnosis of celiac disease and adhering to a gluten-free diet without celiac disease, respectively, which corresponds to an estimated 1.76 million and 2.7 million people in the US population (Table). From 2009 through 2014, the prevalence of celiac disease remained stable over time (0.70% in 2009-2010, 0.77% in 2011-2012, and 0.58% in 2013-2014) and among population subgroups, with the exception of a decrease among men. In contrast, adherence to a gluten-free diet without celiac disease has increased significantly overall (0.52% in 2009-2010, 0.99% in 2011-2012, and 1.69% in 2013-2014) and among population subgroups, with the exception of stable trends among nonwhite participants.

Our findings suggest that the prevalence of celiac disease has remained stable in the US population from 2009 through 2014, although increasing numbers of people are now following gluten-free diets. The two trends may be related because gluten consumption has been identified as a risk factor of celiac disease,⁴ such that steady or even decreasing gluten consumption⁵ may be contributing to a plateau in celiac disease.

Our study has important limitations to consider, including that small numbers of participants in the nationally representative NHANESs were identified as having a diagnosis of celiac disease and adhering to a gluten-free diet without celiac disease. Individuals who met our definition of celiac disease were not confirmed by intestinal biopsy. However, the serologic tests may be more appropriate for large epidemiologic surveys because of their simplicity and operator independence.⁶

There are many reasons, beyond celiac disease, that may account for the increasing popularity of gluten-free diets. First, the public perception is that gluten-free diets are healthier and may provide benefits to nonspecific gastrointestinal symptoms.³ Second, gluten-free products were difficult to obtain in the past but now are more widely available at most large supermarkets and online. Third, there is also an increasing number of individuals with self-diagnosed gluten sensitivity but not the typical enteropathic or serologic features of celiac disease who have improved gastrointestinal health after avoidance of gluten-containing products.

Corresponding Author: Hyun-seok Kim, MD, MPH, Department of Medicine, Rutgers New Jersey Medical School, 150 Bergen St, University Hospital I 248, Newark, NJ 07101 (hk612@njms.rutgers.edu).

Published Online: September 6, 2016. doi:10.1001/jamainternmed.2016.5254

Author Contributions: Dr Kim had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study and design: Kim, Patel, Ahlawat.

Acquisition, analysis, or interpretation of data: Kim, Patel, Orosz, Kothari, Demyen, Pyrsopoulos.

Drafting of the manuscript: Kim, Patel, Orosz.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Kim, Orosz.

Administrative, technical, or material support: Kim, Patel, Orosz, Kothari, Pyrsopoulos.

Study supervision: Kim, Patel, Kothari, Ahlawat.

Conflict of Interest Disclosures: None reported.

Previous Presentation: This study was presented at the Digestive Disease Week Meeting; May 24, 2016; San Diego, California.