Biodegradable plates, cups and straws are often chosen for environmental reasons, but new research suggests some products may pose an unexpected concern for people who need to avoid gluten.
In a laboratory study published in the Journal of Agricultural and Food Chemistry, researchers tested commercially available biodegradable tableware made from wheat byproducts and other plant-based materials to see whether gluten could transfer into foods and drinks under realistic conditions. Out of eight products tested, only one item, a wheat-containing plate, contained detectable gluten and transferred it into food at levels that exceeded gluten-free standards.
The researchers focused on accidental gluten exposure, which can be a serious issue for people with celiac disease or gluten sensitivity. As the authors noted, “biodegradable tableware made from wheat by-products may represent an underestimated source of gluten exposure.” To assess this risk, gluten-free foods were placed on the dishes for 30 minutes at room temperature and then tested for gluten content.
The amount of gluten transferred depended heavily on the type of food. Solid foods showed relatively low levels of transfer. Rice samples reached up to 17 parts per million, which is below the gluten-free threshold of less than 20 ppm. Omelet samples reached up to 30 ppm, which is above the strict gluten-free cutoff but still below the “low-gluten” threshold. Liquids absorbed much higher amounts. Milk reached up to 240 ppm, and vegetable cream reached as high as 2,100 ppm, well above levels considered safe for people who must avoid gluten.
The team also examined whether heating affected gluten transfer. In some cases, microwaving foods on the gluten-containing plate reduced contamination compared with room-temperature samples. The researchers suggested this may be because heat denatures gluten proteins and limits their movement into food.
Importantly, the findings do not suggest that biodegradable tableware broadly poses a gluten risk. Seven of the eight products tested did not contain detectable gluten, highlighting that the issue appears limited to specific wheat-based items rather than compostable products as a whole. Still, the study points to a regulatory gap. Food-contact materials are not required to carry allergen labels, even when they are made from ingredients known to contain allergens.
For people managing celiac disease or gluten sensitivity, the results suggest it may be worth checking the materials used in biodegradable plates or cups, particularly when serving liquids or hot foods. For other consumers, the study serves as a reminder that sustainability features do not always align neatly with allergen safety and that food-contact materials can influence what ends up in a meal.
The authors reported funding from the Regional Government of Andalusia, a predoctoral fellowship and the Margarita Salas postdoctoral fellowship.