Foodborne nanoparticles may predispose infants to food allergy

Foodborne inorganic nanoparticles may impede the development of the immune system and the induction of oral tolerance, leaving infants vulnerable to developing food allergy, according to a review published in Frontiers in Allergy.

Metal oxides and silicate nanoparticles used in or with foods may cross the placental barrier and be excreted in breast milk, Karine Adel-Patient, PhD, senior researcher with the French National Institute for Agriculture, Food, and Environment, and colleagues wrote in the review.

“The widespread use of nanoparticle-based products in the human food chain raises concerns about the risks for human health and highlights the critical need for a thorough risk assessment, which prompted this review,” Adel-Patient told Healio.

“Notably, numerous studies pointed out the deleterious effects of foodborne nanoparticles exposure on immune system, microbiota and intestinal epithelial barrier, which are crucial for the balance of such functions in the gut, and body protection against potential stressors, including potential allergens,” she continued.

Through this review, Adel-Patient said, the researchers aimed to assess the possible consequences of such exposure during pregnancy and early life, which is a window of high susceptibility.

Also, she continued, the researchers explored the association between this exposure and the development of diseases related to immune dysregulation such as food allergy, which she called a disease of still increasing prevalence and a major health concern.

Nanoparticles in food production

When used in phytosanitary applications as nanopesticides and nanofertilizers to protect cultivated plants and treat the environment, these materials raise concerns including how they may contaminate groundwater and the food chain, the researchers wrote.

Inorganic nanoparticles also may be used in food production as anti-foaming and fining substances or as biocidal and anti-caking agents, the researchers continued. For example, silicon dioxide (SiO₂) keeps powdered preparations dry and prevents hardening during storage.

Food contact materials used in ingredient storage, food manufacturing and packaging provide antibacterial and biocidal properties. They also may be used to inform consumers about the state of preservation of the foodstuffs with which they are used. Additionally, they can be used as alternatives to petrochemical packaging materials.

As food additives, inorganic nanoparticles may guarantee food safety as preservatives or antioxidants, improve palatability or appearance via colorants, sweeteners or flavor enhancers, provide texture as thickeners or gelling agents or ensure product stability as emulsifiers or stabilizers.

Effects on the body

Investigations into whether foodborne nanoparticles can cross the placental barrier and present risks for the fetus are ongoing, the researchers wrote, although they noted previous studies have indicated that size plays a role in particles entering the fetal compartment.

Titanium dioxide (TiO₂) nanoparticles have been found in the placenta and meconium, and SiO₂ and silver (Ag) nanoparticles have been found to cross the placental barrier as well.

Gold, iron oxide, zinc oxide and aluminum oxide nanoparticles additionally may be able to penetrate the placenta, with nanoparticle exposure continuing during breastfeeding. Rat and mouse studies have indicated that Ag nanoparticles may be transferred during breastfeeding too.

Nanoparticles that have biocidal properties such as metals and metal oxides, however, may interfere with the development of the gut microbiota in fetuses and infants, the researchers wrote.

Specifically, previous research has indicated that Ag, TiO₂ and SiO₂ nanoparticles have an impact on microbiota composition and global function. Dysbiosis with changes in the Firmicutes/Bacteroidetes (F/B) ratio, decreases in Lactobacillus and increases in Proteobacteria follow.

In addition to an association between shifts in F/B ratio and dysbiosis associated with food allergy, these nanoparticles can disrupt homeostasis in the intestinal microenvironment. This impairs the establishment of the microbiota and the maturation of the epithelial barrier and immune function among infants.

Noting that the body does not absorb 99% of these food additives, which then accumulate in the gut lumen, the researchers said that translocation and accumulation in the gut mucosa may alter intestinal permeability and help disrupt intestinal homeostasis.

In turn, this can circumvent the control passage of food antigen that infants need to induce food tolerance, the researchers wrote, adding that studies already have found evidence for this process involving TiO₂.

Additionally, treatment with TiO₂, SiO₂ or Ag nanoparticles increased the delivery of allergens across the epithelial layer by remodeling tight junctions in a previous study while triggering allergic responses in pre-sensitized mast cells when exposed to milk allergens, according to the researchers.

Further, nanoparticles can directly interact with immune cells in the gut-associated lymphoid tissue, which researchers called essential in establishing tolerance to food allergens.

Previous research has found foodborne titanium and silicate and aluminum particulate matter accumulating in the small intestine, with SiO₂ and TiO₂ absorbed in the distal colon, which also is crucial for tolerance and host defenses.

Conclusions, next steps

Overall, the researchers said these findings indicate that foodborne nanoparticles may change immune homeostasis in addition to the mechanisms of tolerance induction, favoring sensitization to food proteins at mucosal sites while affecting the elicitation phase of allergy.

“All these findings supported our hypothesis that perinatal exposure to foodborne inorganic nanoparticles such as TiO₂ may cause an early disruption of intestinal homeostasis (due to the complex interactions between the microbiota, the intestinal epithelium and the host immune system), thus predisposing to the development of diseases associated with immunological disorders, such as food allergies, later in life,” Adel-Patient said.

Physicians and nutritionists can inform patients about the presence of these nanoparticles in foodstuffs and other everyday products, such as pharmaceutical tablets, toothpastes and cosmetics, as well as about their potential implications, Adel-Patient continued.

“This attempt could improve the treatment they provide by lowering the intake of ultra-processed foods often enriched in inorganic additives, especially for pregnant women, which may lessen the possible risk that these particles can create,” she said.

However, further studies are still needed to uncover how exposure to nanoparticles during pregnancy and infancy could predispose children to food allergy and other immune-related disorders.

“Our next step will be to examine the impact of perinatal exposure to TiO₂ nanoparticles through food on the development of intestinal and systemic homeostasis, as well as the susceptibility of offspring to develop food allergies, using a mother-child mouse model developed in our lab,” Adel-Patient said.

“We also aim to investigate the impact of other types of inorganic nanoparticles routinely used in the agri-food chain, which can lead to chronic exposure of consumers,” she continued. “We will be publishing interesting data on this topic soon.”

For more information:

Karine Adel-Patient, PhD, can be reached at karine.patient@cea.fr.