Biodegradable tableware has become a symbol of environmentally conscious consumption in recent years. In European cafes, fast-food restaurants, and at festivals, plates, cups, and straws made from bamboo fibers, sugar cane, algae, or cereal by-products are increasingly being used. Such products are intended to reduce the amount of single-use plastic, but a new study published in December 2025 in the Journal of Agricultural and Food Chemistry warns of an unexpected danger: some of this "green" tableware can release gluten into food and thus endanger people with celiac disease or non-celiac gluten sensitivity.

A scientific team led by Ángelica Ruiz-Carnicer and Isabel Comino examined several commercially available biodegradable products to determine if they contain gluten residues and whether this allergen can be transferred to gluten-free food under real-use conditions. The results showed that one plate made from wheat by-products contained high concentrations of gluten and, when in contact with certain foods, released it at levels exceeding the currently valid limits for "gluten-free" or "low-gluten" products in the European Union and the United States.

Why is gluten in biodegradable tableware a problem?

For most people, small traces of gluten in tableware are unlikely to cause visible consequences. However, for people with celiac disease, an autoimmune disease in which gluten triggers an immune reaction and damages the lining of the small intestine, even very small amounts of this protein can cause serious long-term damage. The same applies to some people with non-celiac gluten sensitivity, for whom gluten intake can cause digestive issues, fatigue, headaches, and a range of other discomforts, although the mechanism is not the same as in celiac disease.

European regulations stipulate that a product can be labeled as "gluten-free" only if it contains less than 20 parts per million (ppm) of gluten, while the label "very low gluten" can be used for food with less than 100 ppm, under special ingredient processing conditions. Similarly, the US Food and Drug Administration (FDA) requires food labeled as "gluten-free" to contain less than 20 ppm of gluten. Although these are low values, for people who must strictly avoid gluten, such limits are crucial to prevent long-term intestinal damage and complications such as malabsorption, anemia, osteoporosis, or an increased risk of certain malignancies.

However, there is an important regulatory loophole: while the labeling of allergens is strictly prescribed for food and beverages, the same requirements do not apply to materials that come into contact with food, such as plates, cups, straws, or packaging, even when they are made from wheat or other gluten-containing cereals. A consumer can thus receive a meal carefully prepared from certified gluten-free ingredients, but served on a plate that releases gluten – and no one has to provide any information about it.

How the research on biodegradable tableware was conducted

In the latest study, scientists analyzed eight different food-serving products available on the European market. The sample included plates, cups, and straws declared as biodegradable, and according to the manufacturers' information, they were made from wheat by-products or other materials potentially containing gluten. The authors first measured whether the tableware itself contained gluten, independent of contact with food.

Of all the products analyzed, gluten was detected only in one wheat-based plate. Although it could be concluded that the risk is therefore limited, the next phase of the experiment showed that this single contaminated product could be enough to significantly change the composition of the food served on it. To simulate common conditions in households, restaurants, or catering establishments, researchers chose four typical gluten-free foods: omelet, cooked rice, milk, and thick vegetable cream soup.

The food was in contact with individual pieces of tableware for 30 minutes under room conditions. After that, experts measured the gluten content in food samples using standardized analytical methods and compared it with the limits for gluten-free and low-gluten products. Special attention was paid to the difference between solid and liquid foods, as it was assumed that gluten, as a protein, would migrate more easily into a medium in which it dissolves or binds better.

How much gluten ended up in the food?

The results were clear: only the plate that already contained gluten transferred that protein to the food. With plates, cups, and straws made from other materials, such as bamboo or gluten-free plant fibers, researchers found no measurable traces of gluten in either the products themselves or the food that stood on them.

In the case of the contaminated wheat plate, however, gluten migrated into all four tested dishes, but not with equal intensity. In solid food, relatively lower values were recorded. Rice contained up to about 17 ppm of gluten, which is below the limit for a "gluten-free" declaration. The omelet reached about 30 ppm, which exceeds the 20 ppm threshold, but still remains below the 100 ppm limit for the "very low gluten" category. Seemingly, one could conclude that the risk is limited, but for people with severe celiac disease, even such levels can be concerning, especially if such contact is repeated several times a day.

The real problem emerged with liquid and semi-liquid foods. In milk, up to approximately 240 ppm of gluten was measured, which significantly exceeds even the highest permitted limit for "very low gluten." Even more alarming were the results for the vegetable cream soup, in which up to about 2100 ppm of gluten was recorded. Such concentrations manifoldly exceed all currently valid regulatory thresholds and clearly show that a person with celiac disease consuming a seemingly gluten-free cream soup from such a plate could ingest an amount of gluten comparable to consuming a classic wheat-based dish.

Researchers explain that migration was higher specifically in liquid and emulsified foods because such matrices more easily dissolve protein fractions and allow gluten to spread throughout the entire volume. In solid dishes, contact is limited to the surface, so the amount of transferred gluten is smaller, although not necessarily negligible.

Impact of heating: can a microwave oven reduce the risk?

An interesting part of the research was testing the effect of heating food in a microwave oven on the same plate. In some cases, the authors observed that reheating or short cooking in the microwave led to lower levels of gluten compared to samples that stood at room temperature. It is assumed that heat partially denatures the gluten – changing its structure – so the protein's ability to migrate from the plate's surface into the food is reduced.

Despite this, experts emphasize that such an effect should not be relied upon as a "protective mechanism." Denaturation does not necessarily mean complete harmlessness, especially in autoimmune reactions like celiac disease, where even fragmented proteins can retain immunogenicity. Additionally, real-life conditions are very variable: different microwave ovens, heating duration, type of dish, and amount of food can easily lead to results that deviate from those in the laboratory.

Regulatory loophole: tableware without allergen declaration

The study further highlights the problem of the current legislative framework. While food manufacturers are obliged to clearly label the presence of gluten and other common allergens – whether it be wheat, milk, eggs, soy, nuts, or other ingredients – materials that come into contact with food are largely exempt from such obligations. This means that a plate, cup, or straw can be made from wheat straw, bran, or flour without the consumer seeing that information anywhere.

The authors of the paper therefore call on regulatory bodies to consider introducing mandatory gluten labeling, at least for biodegradable materials that come into direct contact with food. Such a change would be in line with the fundamental principle of consumer rights: a person who must avoid a certain ingredient for health reasons should be able to identify it not only in the food but also in everything that comes into contact with that food.

At the same time, the authors emphasize that this is initial research on a limited number of samples and that additional testing is needed. Future studies should cover a wider range of products, different manufacturers and markets, as well as different combinations of foods and usage conditions – from cold drinks to hot dishes served on various types of biodegradable tableware.

What about other allergens in "green" tableware?

Gluten was the focus of this research, but the same concept applies to other allergens that can be found in biodegradable materials. Products made from milk, egg, or soy proteins already exist on the market, as well as tableware enriched with nuts or their shells. In people allergic to these ingredients, even microscopic amounts can trigger strong reactions, from skin rashes to anaphylactic shock.

Scientists warn that so far there is very little data on the extent to which such materials can release allergens into food under real conditions, especially with prolonged contact, repeated use, or exposure to heat. This is exactly why the study's authors point out the necessity of expanding research to other allergens to prevent unexpected reactions in the most sensitive consumer groups.

Growth of "green" alternatives after the ban on single-use plastics

The rapid expansion of biodegradable tableware is not happening in a vacuum. After the European Union banned a range of single-use plastic products in 2021, such as classic straws, plastic cutlery, and certain types of packaging, the market reacted quickly by developing new materials. Bamboo fibers, sugar cane, corn starch, but also residues of cereals like wheat, rye, or oats have become attractive raw materials for "green" plates, cups, and other utensils.

For manufacturers, using agricultural by-products is a logical step: it is a cheap material that would otherwise end up as waste or low-value animal feed, while also fitting into the narrative of the circular economy and plastic reduction. However, when it comes to allergens, "natural" does not necessarily mean "safe." Wheat bran or straw still contains protein fractions of gluten which, as the new study shows, can be transferred to food even if the food itself was produced gluten-free.

What can consumers and restaurateurs do today?

Until regulations adapt to new scientific findings, the responsibility largely remains with consumers and restaurateurs. Experts advise that people with celiac disease or severe gluten sensitivity, wherever possible, request information about the composition of the biodegradable tableware used to serve their meals.

If information is not available or the manufacturer does not state the raw materials from which the tableware is made, the safest approach is to avoid products for which there is even the slightest suspicion that they contain gluten-containing cereals. In practice, this may mean using classic ceramic or glass tableware in establishments that offer gluten-free dishes, as well as clear communication between chefs, waiters, and guests about what the food will be served on.

For restaurateurs targeting an audience with special dietary needs, experts recommend creating internal guidelines: clearly separate tableware for gluten-free dishes, avoid biodegradable plates made from wheat or other gluten materials, educate staff about gluten-related diseases and cross-contamination risks – not only from the kitchen but also from tableware and packaging.

Balancing sustainability and food safety

The concluding message of the researchers is not that biodegradable tableware should be abandoned, but that sustainability must not be built at the expense of the safety of the most sensitive consumers. Developing materials that decompose more easily in the environment is extremely important for reducing plastic waste, but it is necessary to take into account allergens and other potential health risks.

Manufacturers are encouraged to prioritize gluten-free materials when choosing raw materials – for example, sugar cane fibers, bamboo, wood, or certain types of starch that do not originate from wheat, rye, barley, or oats. For products where the use of gluten-containing cereals is inevitable, scientists suggest a clear declaration of the presence of gluten, even if such labeling is not currently legally mandatory. This would allow people with celiac disease and other gluten-related disorders to make an informed decision about which products to use and in which situations.

The new research, published in mid-December 2025, can therefore be seen as an important step toward understanding potential risks associated with biodegradable tableware. At the same time, it opens space for a broader discussion among scientists, regulators, patient associations, and industry on how to harmonize climate goals, economic needs, and, above all, food safety for all consumers – including those for whom even a small trace of gluten can represent a major problem.