Researchers from Binghamton University, State University of New York, have determined that food packaging may have a negative impact on the operation of the digestive tract according to a new study.
"We found that zinc oxide (ZnO) nanoparticles at doses that are relevant to what you might normally eat in a meal or a day can change the way that your intestine absorbs nutrients or your intestinal cell gene and protein expression," said Gretchen Mahler, associate professor of biomedical engineering.
Thanks to their antimicrobial properties, these ZnO nanoparticles are found in the lining of various canned foods. Likewise, they are also used to help prevent the staining of sulfur-producing foods.
Using mass spectrometry, researchers looked at foods such as canned corn, asparagus, tuna and chicken and estimated that 100 times the daily dietary allowance of zinc had transferred to the canned food. Mahler then investigated how the particles might impact the digestive tract.
“People have looked at the effects of nanoparticles on intestinal cells before, but they tend to work with really high doses and look for obvious toxicity, like cell death," said Mahler. "We are looking at cell function, which is a much more subtle effect, and looking at nanoparticle doses that are closer to what you might really be exposed to."
"They tend to settle onto the cells representing the gastrointestinal tract and cause remodeling or loss of the microvilli, which are tiny projections on the surface of the intestinal absorptive cells that help to increase the surface area available for absorption," said Mahler. "This loss of surface area tends to result in a decrease in nutrient absorption. Some of the nanoparticles also cause pro-inflammatory signaling at high doses, and this can increase the permeability of the intestinal model. An increase in intestinal permeability is not a good thing—it means that compounds that are not supposed to pass through into the bloodstream might be able to."
Despite having looked at the effects in the lab, Mahler said the long-term health implications are still unknown.
"It is difficult to say what the long-term effects of nanoparticle ingestion are on human health, especially based on results from a cell culture model," said Mahler. "What I can say is that our model shows that the nanoparticles do have effects on our in vitro model, and that understanding how they affect gut function is an important area of study for consumer safety."
For now, the researchers are looking at how chickens (as an animal model) respond to nanoparticle ingestion.
"We have seen that our cell culture results are similar to results found in animals and that the gut microbial populations are affected. Future work will focus on these food additive-gut microbiome interactions," said Mahler.
The study, called "ZnO nanoparticles affect intestinal function in an in vitro model," was published in the journal Food & Function.