Gluten has a central role in the pathogenesis of several gluten-related disorders, with coeliac disease being one of the most well-known. A rigorous gluten-free diet is recognized as the only safe and efficient coeliac disease therapy. This study intended to use the enzyme-linked immunosorbent assay (ELISA) R5 Méndez method to determine gluten contamination in labelled gluten-free food products marketed in China and to evaluate the performance of two ELISA platforms (the Neogen Veratox^® R5 and the Romer Labs AgraQuant^® G12) for analyzing gluten, using R5 Méndez as the reference. In 2024, 119 prepackaged products labelled as gluten-free were purchased from internet suppliers. The results showed that among the 119 products, 13.4% contained gluten exceeding 20 mg/kg, and 5.0% contained over 100 mg/kg, ranging from 333.1 to 2737.4 mg/kg. When the threshold for gluten-free products was 20 mg/kg, the two ELISA platforms yielded results comparable to R5 Méndez. However, when the threshold was 10 mg/kg and 5 mg/kg, the McNemar x² test showed significant differences between the proportions of positive results of the two ELISA platforms and R5 Méndez (p-value < 0.05); using R5 Méndez as the reference, the two ELISA platforms showed 53.1% to 70.3% positive predictive values, suffering the drawback of high false-positive results. When using stricter gluten limits of ≤10 mg/kg and ≤5 mg/kg, different ELISA platforms may produce different results for the same food product. These findings highlight the need for China to accelerate the development of national standards for gluten-free foods, and for food regulatory agencies to impose requirements of production that lead to the prevention of gluten contamination, confirmed by the possible monitoring of such compliance through routine sampling and testing. Such measures will no doubt contribute to protecting and improving the health of patients with gluten-related disorders.

Gluten plays a central role in the development of several gluten-related disorders, with coeliac disease being one of the most well-known. A strict gluten-free diet is currently recognised as the only safe and effective treatment for coeliac disease. This study aimed to determine the degree of gluten contamination in labelled gluten-free food products available on the Chinese market. In 2024, 119 prepackaged products labelled as gluten-free were purchased from internet suppliers, 33 of which were imported. Each product was analysed in duplicate, using the cocktail solution (patented) to extract gluten and the RIDASCREEN® Gliadin sandwich R5 ELISA to determine the gluten content. The results showed that among the 119 products, 86 (72.3%) contained gluten less than 5 mg/kg, 12 (10.1%) between 5 and 10 mg/kg, 5 (4.2%) between 10 and 20 mg/kg and 16 (13.4%) above 20 mg/kg. None of the products imported contained gluten above 20 mg/kg, while 16 out of 86 (18.6%) Chinese-made products did. There was a significant difference in the prevalence of gluten contamination between imported and domestically made products (p < 0.01). These findings highlight the need for Chinese food regulatory agencies to impose requirements of production that lead to prevent gluten contamination, confirmed by possible monitoring of such compliance through routine sampling and testing.

Background: The prevalence of adverse food reactions (AFRs) in adults appears to be on the rise. Among the various mechanisms underlying AFRs, reduced histamine degradation capacity is one of the crucial pathophysiological bases. Diamine oxidase (DAO) is the key enzyme responsible for degrading exogenous histamine from food, and certain single nucleotide polymorphism (SNP) variants in the amine oxidase copper-containing 1 (AOC1) gene encoding this enzyme are closely associated with reduced DAO activity. Methods: In an epidemiological study of food allergy among adults in Ganzhou, eastern China, we collected oral mucosal samples from 241 cases with self-reported AFRs and 204 healthy controls without a history of AFRs or allergic diseases to analyze three SNP variants associated with DAO deficiency (rs10156191, rs1049793, and rs2052129). Results: The prevalence of genetic DAO deficiency among adults with AFRs was 78.8% (95% CI: 73.1–83.8), with rs1049793 being the most frequent SNP variant. There were no significant differences in the distribution of the three SNP variants and allele variants between AFR cases and controls. Among AFR cases, the proportion of individuals with DAO deficiency who self-reported ≥3 AFR symptoms was significantly higher than that in the normal DAO activity group (24.7% vs. 6.4%; P = 0.006). Furthermore, the number of SNP variants was significantly, albeit weakly, positively correlated with the number of self-reported AFR symptoms (r_s = 0.218, P = 0.001). The proportion of AFR cases presenting with ≥3 symptoms exhibited a stepwise increase with the accumulation of SNP variants. Conclusions: There is a high prevalence of genetic DAO deficiency among adults with AFRs in Ganzhou. AOC1 genotyping is helpful for identifying genetically susceptible individuals who are prone to experiencing multi-system AFR symptoms.