Less Hidden Celiac Disease but Increased Gluten Avoidance without Diagnosis in the United States: Findings from the National Health and Nutrition Examination Surveys from 2009 to 2014
Mayo Clin Proc January 2017; 92(1); 30-38
This article provides evidence based data about the use of the gluten free diet (GFD) in the U.S. There have been many market based reports indicating the growing number of people who turn to the GFD, from both the food industry and market research groups. To date these reports have indicated increased use of the GFD based on retail market sales and growth of the gluten free segment in the food industry, but have not provided any insight on the end user.
This article provides evidence based data about the use of the gluten free diet (GFD) in the U.S. There have been many market based reports indicating the growing number of people who turn to the GFD, from both the food industry and market research groups. To date these reports have indicated increased use of the GFD based on retail market sales and growth of the gluten free segment in the food industry, but have not provided any insight on the end user.
Dr. Murray and his team from the Mayo Clinic have used the comprehensive data from the National Health and Nutrition Examination Surveys (NHANES) to differentiate between different users of the GFD.
The NHANES surveys are conducted every two years to evaluate the U.S. population’s health, nutritional status, and monitor changes in food intake patterns. The NHANES surveys approximately 5,000 non-institutionalized individuals from across the country. The survey design is a complex, stratified, multistage, and probability-based sample.
The NHANES data was gathered by standardized household interviews, physical examinations, and biological samples. The researchers used positive serology results (both tTG IgA and EMA IgA) to confirm a diagnosis of celiac disease. People without celiac disease avoiding gluten (PWAG) were identified if the respondent had negative serology but responded to two celiac disease-related questions indicating adherence to a GFD without a health professional’s diagnosis of celiac disease.
The results of the study indicated the prevalence of celiac disease remained stable at 0.7% over the time period surveyed from 2009–2014. Of note was the significant decrease (P = 0.01) in the prevalence of undiagnosed celiac disease. The rate of undiagnosed celiac disease decreased from 0.6% in the 2009–2010 survey to 0.3% in 2013–2014 survey.
In contrast to the stable rate of the prevalence of celiac disease, the number of participants who reported using a GFD increased over each survey time period. In the 2009–2010 survey, the use of the GFD by PWAG was 0.6%, increasing to 1.2% in the 2011–2012 survey, and 2.1% in the 2013–2014 survey. This represents a threefold increase in the use of the GFD in PWAG.
This study provides an in-depth insight into the landscape of celiac disease and the GFD in the U.S. The popular press reports about the GFD and weight loss are of special concern. In the review of GF products, Kulai and Rashid (2014) found that many processed GF foods were not only significantly higher (p=0.003) in fat and carbohydrates, but were also lower in protein, as well as iron and folate, compared to their wheat-based counterparts (p < 0.001). However, the 2012 study by Shepherd and Gibson found that deficiency of fiber and folate among individuals with celiac disease on the GFD may be associated with poor food choices rather than with GF products and foods.
Murray and colleagues conclude that in light of the increased use of the GFD by PWAG as well as the increased number of individuals diagnosed with celiac disease further research is needed. The scope of this research should include not only the evaluation of the nutritional content of gluten free food products but also overall nutritional adequacy of dietary patterns of people on the GFD compering to the general population.
References
The NHANES surveys are conducted every two years to evaluate the U.S. population’s health, nutritional status, and monitor changes in food intake patterns. The NHANES surveys approximately 5,000 non-institutionalized individuals from across the country. The survey design is a complex, stratified, multistage, and probability-based sample.
The NHANES data was gathered by standardized household interviews, physical examinations, and biological samples. The researchers used positive serology results (both tTG IgA and EMA IgA) to confirm a diagnosis of celiac disease. People without celiac disease avoiding gluten (PWAG) were identified if the respondent had negative serology but responded to two celiac disease-related questions indicating adherence to a GFD without a health professional’s diagnosis of celiac disease.
The results of the study indicated the prevalence of celiac disease remained stable at 0.7% over the time period surveyed from 2009–2014. Of note was the significant decrease (P = 0.01) in the prevalence of undiagnosed celiac disease. The rate of undiagnosed celiac disease decreased from 0.6% in the 2009–2010 survey to 0.3% in 2013–2014 survey.
In contrast to the stable rate of the prevalence of celiac disease, the number of participants who reported using a GFD increased over each survey time period. In the 2009–2010 survey, the use of the GFD by PWAG was 0.6%, increasing to 1.2% in the 2011–2012 survey, and 2.1% in the 2013–2014 survey. This represents a threefold increase in the use of the GFD in PWAG.
This study provides an in-depth insight into the landscape of celiac disease and the GFD in the U.S. The popular press reports about the GFD and weight loss are of special concern. In the review of GF products, Kulai and Rashid (2014) found that many processed GF foods were not only significantly higher (p=0.003) in fat and carbohydrates, but were also lower in protein, as well as iron and folate, compared to their wheat-based counterparts (p < 0.001). However, the 2012 study by Shepherd and Gibson found that deficiency of fiber and folate among individuals with celiac disease on the GFD may be associated with poor food choices rather than with GF products and foods.
Murray and colleagues conclude that in light of the increased use of the GFD by PWAG as well as the increased number of individuals diagnosed with celiac disease further research is needed. The scope of this research should include not only the evaluation of the nutritional content of gluten free food products but also overall nutritional adequacy of dietary patterns of people on the GFD compering to the general population.
References
- Murray, J A , et al. Less Hidden Celiac Disease but Increased Gluten Avoidance without Diagnosis in the United States: Findings from the National Health and Nutrition Examination Surveys from 2009 to 2014. Mayo Clin Proc January 2017; 92(1); 30-38;
- Kulai, T and Rashid, M. Assessment of Nutritional Adequacy of Package Gluten Free Food Products. (2014) Can J Diet Pract Res 75(4):186-90;
- Shepherd, S J and Gibson, PR. Nutritional Inadequacies of the Gluten Free Diet in Both Recently-Diagnosed and Long-Term Patients with Coeliac Disease. (2012) J of Hum Nut & Diet.
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