Gluten contamination in labelled gluten-free, naturally gluten-free and meals in food services in low-, middle- and high-income countries: a systematic review and meta-analysis

Abstract

The gluten-free diet is based on the consumption of foods without gluten, which aims to manage celiac disease. The concern of celiac patients is that these foods should be safe. However, gluten contamination can affect these foods. The objectives of this review and meta-analysis were first, to identify articles that detected gluten contamination in gluten-free foods using validated methods. Second, to quantify the overall prevalence of gluten contamination of naturally gluten-free foods, labelled gluten-free products, and meals prepared in food services. Third, to highlight the influence of the country’s income and the period of study on this prevalence. The studies were identified in Scopus, Science Direct, Web of Science, PubMed, and Google Scholar. Forty articles were included according to PRISMA guidelines. The statistical meta-analysis was performed using MedCalc 19 software. The results show that in the gluten-free foods analysed, the overall prevalence of gluten contamination was estimated at 15.12% (95% CI: 9.56%–21.70%), with more than 20 mg/kg of gluten. Naturally gluten-free foods were significantly more contaminated than labelled gluten-free products and than meals in food services (28.32%; 9.52%; 4.66% respectively; p < 0.001). Moreover, it was noticed that oats were the most contaminated food. In addition, the prevalence of gluten contamination has significantly decreased over time. The majority of the studies were carried out in upper-middle-income and high-income countries, while only one study was conducted in lower-middle income countries. Therefore, it is necessary to implement preventive actions to reduce gluten contamination, ensuring safe gluten-free foods for celiac patients, including low-income countries.

Gluten‐free diet for pediatric patients with coeliac disease: A position paper from the ESPGHAN gastroenterology committee, special interest group in coeliac disease

“…In Italy, gluten‐free pizzas bought at certified restaurants 70 and regular restaurants 71 were both below 20 mg/kg. Naturally, gluten‐free meals were more likely to cross‐contact with gluten than meals labeled gluten‐free 68 . In US restaurants, 1% 65 and 25% 72 of gluten‐free foods fried in the same fryer as gluten‐containing foods had a gluten content >20 mg/kg.…”

“…The prevalence of hazardous gluten content in products sold as gluten‐free varies between studies in different countries: 6% in Australia, 66 10% in Ireland 67 (the majority >100 mg/kg), 0% in Italy 60 . Since 2009, the prevalence of gluten cross‐contact in food services reported in the scientific literature has decreased, to overall 2.93% (95% confidence interval 1.60%, 4.91%) 68 . In countries where a rigorous legislation is not in place, or that do not have the obligation to inform customers on allergens in foods, 65–68 the prevalence of hazardous gluten cross‐contact seems to be more prevalent than in the EU.…”

Commercial oats in gluten-free diet: A persistent risk for celiac patients

“…The successful application of the “Purity Protocol” has shown that is indeed possible to produce safe oats in compliance with the legislation and suitable for celiac patients on gluten-free diet ( 23 ). Thus, although there is robust evidence indicating that oats are indeed frequently contaminated ( 15 , 22 , 24 ), at the same time improving the practice of using special gluten-free oats cultivars and supervision of oat production and manufacturing appears as a potent line of action to obtain good, safe products.…”

Risk of consuming products with or without precautionary wheat or gluten labelling for persons with coeliac disease

“…This is reflected in the results from Bustamante et al (2017) showing that the level of gluten contamination in cereal based CGF and PWG has decreased in the period from 1998 to 2016. In addition, Guennouni et al (2021) found that the prevalence of gluten contamination in all types of gluten free foods decreased between the time periods 2000-2008 and 2015-2020. In food allergy risk assessment, it is assumed that if an allergic person includes a product in the diet, the amount consumed is the same as in the general population. We made the same assumption in this study and used data from the Danish national food survey grouped to be suitable for food allergy risk assessment (Birot et al, 2017).…”