Exposure sources, amounts and time course of gluten ingestion and excretion in patients with coeliac disease on a gluten-free diet.

BACKGROUND: A major deficit in understanding and improving treatment in coeliac disease (CD) is the lack of empiric data on real world gluten exposure. AIMS: To estimate gluten exposure on a gluten-free diet (GFD) using immunoassays for gluten immunogenic peptides (GIP) and to examine relationships among GIP detection, symptoms and suspected gluten exposures METHODS: Adults with biopsy-confirmed CD on a GFD for 24 months were recruited from a population-based inception cohort. Participants kept a diary and collected urine samples for 10 days and stools on days 4-10. 'Doggie bags' containing » portions of foods consumed were saved during the first 7 days. Gluten in food, stool and urine was quantified using A1/G12 ELISA. RESULTS: Eighteen participants with CD (12 female; age 21-70 years) and three participants on a gluten-containing diet enrolled and completed the study. Twelve out of 18 CD participants had a median 2.1 mg gluten per exposure (range 0.2 to >80 mg). Most exposures were asymptomatic and unsuspected. There was high intra-individual variability in the interval between gluten ingestion and excretion. Participants were generally unable to identify the food. CONCLUSIONS: Gluten exposure on a GFD is common, intermittent, and usually silent. Excretion kinetics are highly variable among individuals. The amount of gluten varied widely, but was typically in the milligram range, which was 10-100 times less than consumed by those on an unrestricted diet. These findings suggest that a strict GFD is difficult to attain, and specific exposures are difficult to detect due to variable time course of excretion.

Development of the Dietitian Integrated Evaluation Tool for Gluten-free Diets (DIET-GFD).

OBJECTIVES: Celiac disease (CD) treatment involves a gluten-free diet (GFD). There is no standardized tool for dietitians to objectively grade GFD adherence. This study aimed to develop a standardized tool for dietitians to evaluate and communicate GFD adherence. METHODS: Participants were recruited from the Manitoba Celiac Disease Cohort. Using a consensus process, an expert panel of gastroenterologists, dietitians, clinical health psychologists, and persons with CD developed the Dietitian Integrated Evaluation Tool for Gluten-free Diets (DIET-GFD). Two dietitians performed duplicate assessments of 27 newly diagnosed participants who had been advised to follow a GFD. The global adherence scale was further revised after panel discussions of the cases where there was uncertainty or discordance on dietitian ratings. Subsequently, the scoring system was evaluated using duplicate assessments of an additional 37 participants with CD. Interrater agreement was assessed using square-weight Cohen's kappa. RESULTS: The DIET-GFD includes features related to frequency and quantity of gluten ingestion based on self-reporting and food frequency evaluation, shopping and dining habits, how and where food is prepared and consumed, eating behaviors, and label reading skills. The DIET-GFD global assessment is reported using a 10-point ordinal descriptive scale, ranging from 1 (takes few precautions and regularly eats gluten) to 10 (no gluten in kitchen and rarely eats food prepared outside the home). The kappa of DIET-GFD global assessment was 0.845, which indicates excellent agreement. CONCLUSIONS: DIET-GFD is a useful tool for dietitians to evaluate GFD adherence. Further studies are needed to confirm that the score from the DIET-GFD is reliable across various settings.

Can individuals with celiac disease identify gluten-free foods correctly?

BACKGROUND & AIMS: Patients with celiac disease (CD) often report inadvertent gluten exposures and challenges reading labels. The most common cause of non-responsive CD is gluten exposure. We aimed to assess whether recently diagnosed CD patients can determine whether a food is gluten-free based on labeling, and to assess skills over time. A secondary aim was to identify factors associated with label reading proficiency. METHODS: Inception cohort with follow-up at 6, 12, and 24 months after diagnosis. Participants were asked to determine whether 25 food items were gluten-free based on labeling information. Diet adherence was assessed using the Celiac Diet Assessment Tool (CDAT) and the Gluten-Free Eating Assessment Tool (GF-EAT). 144 adults with newly diagnosed celiac disease were enrolled. The initial quiz at 6 months was completed by 83%. Quizzes were completed by 72% at 12 months and 70% at 24 months. RESULTS: Median overall accuracy scores were: 23/25, 24/25 and 21/25 at 6, 12 and 24 months respectively. Gluten-free products with explicit "gluten-free" claims had the fewest errors. Quiz scores were not correlated with tTG IgA levels, or CDAT or GF-EAT scores. Diet adherence was generally good (>85% with CDAT <13 suggesting adequate GFD adherence); however, at 24 months, only 11% reported no gluten exposure. CONCLUSIONS: CD patients may be unable to consistently choose gluten-free foods based on product labeling. Explicit identification of gluten-free products may be helpful. Label reading ability appears stable over time. Further studies are needed to evaluate whether erroneous label reading or misleading labels are associated with persistent villous atrophy.

Is it gluten-free? Relationship between self-reported gluten-free diet adherence and knowledge of gluten content of foods.

OBJECTIVE: To assess the relationship between self-reported adherence to a gluten-free diet (GFD) and the ability to determine correctly the appropriateness of particular foods in a GFD. METHODS: Persons with celiac disease were recruited through clinics and support groups. Participants completed a questionnaire with items related to GFD information sources, gluten content of 17 common foods (food to avoid, food allowed, and food to question), GFD adherence, and demographic characteristics. Diagnosis was self-reported. RESULTS: The 82 respondents (88% female) had a median of 6 y GFD experience. Most (55%) reported strict adherence, 18% reported intentional gluten consumption and 21% acknowledged rare unintentional gluten consumption. Cookbooks, advocacy groups, and print media were the most commonly used GFD information sources (85-92%). No participant identified correctly the gluten content of all 17 foods; only 30% identified at least 14 foods correctly. The median score on the Gluten-Free Diet Knowledge Scale (GFD-KS) was 11.5 (interquartile ratio, 10-13). One in five incorrect responses put the respondent at risk of consuming gluten. GFD-KS scores did not correlate with self-reported adherence or GFD duration. Patient advocacy group members scored significantly higher on the GFD-KS than non-members (12.3 versus 10.6; P < 0.005). CONCLUSIONS: Self-report measures which do not account for the possibility of unintentional gluten ingestion overestimate GFD adherence. Individuals who believe they are following a GFD are not readily able to correctly identify foods that are GF, which suggests ongoing gluten consumption may be occurring, even among patients who believe they are "strictly" adherent. The role of patient advocacy groups and education to improve outcomes through improved adherence to a GFD requires further research.