Cross-section of chicken intestine with cells that may be affected by food nanoparticles. (Credit: Cornell University)

Metal oxide nanoparticles—easily ingested due to their broad use in the food industry as an anticaking agent and food coloring—can damage and disrupt the human gut, according to a recent study. 

Scientists at Cornell University and Binghamton University found that certain nanoparticles popularly used as food additives, particularly titanium dioxide and silicon dioxide, can have a negative impact on gut functionality. They were also found to be detrimental to key digestive and absorptive proteins.

Their previous work performed in vitro on the cells lining the gut analyzed certain nanoparticles like titanium dioxide, silicon dioxide, zinc oxide, and iron oxide—all commonly used in the food and pharmaceutical industries. Now, the team narrowed their focus to specific metal oxide nanoparticles, using doses that are appropriate for human consumption.  

In this study published in the journal Antioxidants, the research team analyzed food-grade titanium dioxide and silicon dioxide taken at normal doses in the Tako laboratory’s in vivo system. This system is somewhat similar to that of the human body’s physiology.

The team injected the nanoparticles into over 60 chicken eggs. Then, they were allowed to hatch.

Upon examination, the scientists observed alterations in the functional, structural, and microbial biomarkers in the blood, as well as in the duodenum (the first part of the small intestine just below the stomach) and the cecum (a pouch connected to the intestines).

They found that the nanoparticles affected the animal’s gut development and transport of minerals. The gut bacterial population was also affected, as was the brush border membrane (the intestine’s digestive and absorptive surface). 

Since we are exposed daily to nanoparticles—either through food, drinking water, or our surroundings—the scientists were prompted to understand the effects these nanoparticles may have on gastrointestinal health and development.

“We don’t really know how much we consume; we don’t really know the long-term effects of this consumption,” says Prof. Dr. Elad Tako, the lead author of the study. “Here, we were able to demonstrate some of these effects, which is a key to understanding gastrointestinal health and development.”

Moving forward, the team also assessed the metabolism of zinc oxide and iron oxide in the blood, cecum, and duodenum of the animals. Zinc oxide is used as a micronutrient supplement. Iron oxide is an iron fortification supplement. Both are employed for the mineral fortification of foods. 

Researchers found that exposure to zinc oxide nanoparticles increased the amount of healthy gut bacteria, increased gut development, and acted as compensatory mechanisms following any damage to the intestines. 

On the other hand, iron oxide nanoparticles were found to be a better choice for iron fortification, though they altered gut functionality and development.

In conclusion, this study shows the potential ability of nanoparticles to disrupt microbiota composition and intestinal health and development upon consumption.

Exposure to nanoparticles is no doubt unavoidable. While the researchers are not suggesting the use of these nanoparticles be terminated, they do believe that people should be aware.

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