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Investigating the Role of Environmental Irritants in Food Allergy Development
Recent research suggests that environmental “irritants” like detergents, microplastics, and even pollens might be playing a role in the development of food allergies. At the French-speaking Allergy Congress, Virginie Doyen, MD, a pneumologist at University Hospital Namur in Belgium, reviewed the current state of knowledge on this topic. According to Dr. Doyen, the relationship between these irritants and food allergies is complex and multifactorial, involving genetic, epigenetic, internal, and external environmental factors.
Dietary Habits and Food Allergies
Research indicates that poor dietary habits may contribute to the development of food allergies. Diets high in additives, preservatives, sugars, and fats, but low in short-chain fatty acids, are linked to an increased risk of food allergies. Conversely, a Mediterranean diet during pregnancy and breastfeeding, as well as a diet rich in fruits and vegetables during childhood, appears to reduce this risk.
One proposed mechanism is that a lack of dietary fiber could lead to the degradation of intestinal mucus via the microbiome. This mucus plays a crucial role in the gut by limiting exposure to antigens and maintaining immune tolerance. It is rich in glycoproteins, carbohydrates, antimicrobial peptides, and immunoglobulin A (IgA). The microbiome, which has immunomodulatory effects, can degrade this mucus if it is altered by poor diet, potentially compromising the intestinal barrier.
Impact of Ultrapressed Foods
Studies using cellular and animal models have shown that consuming large amounts of advanced glycation end products, commonly found in ultraprocessed foods, can alter the intestinal barrier. These foods seem to disrupt the tight junctions between epithelial cells, which are essential for maintaining the integrity of the intestinal barrier. Exposure to these foods reduces the levels of key proteins like occludin and ZOT1, allowing allergens and other irritants to pass through the barrier.
Furthermore, such exposure increases the production of Th2-type proinflammatory cytokines and alarm signals like interleukin (IL)-25 and IL-33, which direct the Th2-type immune response. Dysbiosis, or an imbalance in the gut microbiome, and a less diverse microbiome are often observed in individuals with food allergies, suggesting that microbiome alterations might precede the fragility of the intestinal barrier.
Role of Chemical Agents
Chemical agents such as detergents, emulsifiers, and microplastics might also indirectly contribute to food allergy symptoms in sensitized individuals. Studies have shown that emulsifiers like lecithin, carboxymethylcellulose, and polysorbate 80 can affect the intestinal mucus, leading to modifications in the microbiota and triggering inflammatory processes.
Detergents, such as those found in dishwasher residues, can alter the epithelial barrier when tissues are exposed to them, causing overexpression of genes involved in immune response and inflammation. Sodium dodecyl sulfate, a common detergent in toothpaste, has been shown to decrease the integrity of the epithelial barrier, promoting inflammation and remodeling of the intestinal epithelium.
Microplastics and Pollens
Microplastics, which are increasingly present in our environment, have been shown to penetrate tissues and induce dysbiosis in mice, reducing mucus production and altering the intestinal barrier function. Pollution and climate change have increased protease activity in pollens, which are linked to respiratory allergies and might also affect the intestinal barrier. Studies have shown that kiwi allergen actinidin can increase intestinal permeability.
Future Directions
The evidence suggests that food allergies are associated with an altered digestive epithelial barrier and that environmental irritants might contribute to this phenomenon. Dr. Doyen proposes several potential therapeutic approaches, including antialarmin treatments, which block inflammatory cascades at the epithelial level, and modifying the microbiota to enhance mucus production. Reducing exposure to toxic products, without completely eliminating them, might also help mitigate the risk.
As our understanding of the links between environmental irritants and food allergies evolves, it could lead to more effective prevention and treatment strategies, potentially reducing the incidence of food allergies in the population.
