The Tako Lab/Cornell University

The Tako Lab injected doses of titanium dioxide into the intestines of the embryonic chicken model in order to view its cells.

March 8, 2023

Study Finds that Nanoparticles in Food May Affect Intestine Function and Microbiome

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Through a collaboration between Cornell and the State University of Binghamton in February, scientists found that food grade nanoparticles may potentially have detrimental effects on the function and shape of the intestine. This collaboration was funded by the National Institutes of Health.

Food grade nanoparticles are small metals used as coloring or anti-caking agents in food products. Anti-caking agents prevent the clumping of foods, such as powders. 

The study focused on the nanoparticles titanium dioxide, silicon dioxide, zinc oxide and iron oxide. Titanium dioxide and silicon dioxide are two of the most commonly used nanoparticles in the food industry, whereas zinc and iron oxide are often used in supplements. 

Despite the ubiquity of titanium dioxide and silicon dioxide in the food industry, there is a lack of transparency surrounding the amount people consume. Because the Food and Drug Administration does not require companies to report the presence of nanoparticles on food labels, there is no accurate measurement for the amount people consume. 

According to Prof. Elad Tako, food science and technology, this lack of regulation poses a potential problem. 

“We consume them without knowing how much we consume nor the long term effects of consuming them,” Tako said.

However, Tako refrains from labeling all nanoparticles as detrimental to long term health, although he stated in his study there has been evidence that long-term consumption of titanium dioxide can pose health issues in the future. 

The questions regarding how nanoparticles may affect digestion motivated their study that focused on exploring the effects of these nanoparticles on intestine tissue behavior, development, shape of the intestine and the microbiome of the intestine. The microbiome refers to the microbes, such as bacteria, that live in the intestine. 

The Tako Lab observed a shift in bacterial populations in the intestine following the consumption of nanoparticles, as well as noted that titanium dioxide harmed the function of the intestine. 

Researchers saw that titanium dioxide led to a smaller surface area of the villi of the duodenum, which is important for digestion. The duodenum is a part of the small intestine that is responsible for absorbing nutrients from food. As such, the small intestine villi, resembling hairlike projections, is especially important in maximizing surface area for greater absorption. 

The researchers used Tako’s embryonic chicken model, injecting doses typical for a human into the prenatal chicken and collecting samples from the chicken’s intestines. The results revealed that even after a short period of exposure, the microbiome was affected, with increases in the populations of E.coli and other harmful bacteria following exposure to silicon dioxide, zinc and iron oxide.  

The study observed the effects in vivo, or within a living organism, building on their previous study that focused on an in vitro, or cellular, system. 

The scientists used chickens because they are genealogically similar to humans, as well as easier to manipulate due to the separate system of the embryo when in egg form, compared to other common model organisms such as rats.

“It is very naive, so it’s very easy to test the effect of a specific ingredient. In this case, it was the specific food grade nanoparticles, but not in the context of a diet because you just introduce them [to the embryo], and any results you collect are directly associated with the substance you introduced,” Tako said. “This makes the results or potential conclusions extremely accurate.”

However, the chickens were only exposed to nanoparticles for a short period of four days because the team didn’t know what results to expect. The nanoparticles were injected into the amniotic fluid at day 17 of their development, which was then ingested by the embryo as part of a natural process to prepare to hatch. When the chicken hatched on day 21, the samples were collected the same day. 

Tako noted this limitation of the study and explained the scientists’ plans for further research using a long term feeding trial to investigate what effects are seen over a longer period of time, funded through an NIH grant. 

In light of these findings, Tako said it is important to refrain from concluding that nanoparticles are detrimental for people’s health. Although evidence from the study shows food grade nanoparticles can negatively impact gut function, researchers found that despite changes to the function and structure of the intestine, iron oxide had the potential to positively increase iron content. However, there are still many lingering questions on what these nanoparticles mean for long-term health. 

“Again, we’re not trying to say that this is bad for you or that you should stop using it or consuming it. It’s just that we really need to know more, Tako said. “We need to further investigate.”