Researchers have found that chronic exposure to a common food additive may affect how cells in the small intestine absorb nutrients and protect against pathogens.
In a study published in the journal NanoImpact, Gretchen Mahler and colleagues showed that titanium dioxide can significantly decrease small intestinal cell ability related to absorbing nutrients and acting as a pathogen barrier when nanoparticles of the food additive are consumed frequently.
According to Mahler, titanium dioxide has been used as a common food additive for a long time and it's not dangerous. However, the researchers were interested in some of its more subtle effects and believed that consumers should be informed about these effects.
Earlier works have delved on how the titanium dioxide nanoparticles affect microvilli, the absorptive projections found on intestinal cell surfaces, but Mahler pointed out that their research is focused on analyzing exposures at lower concentrations.
"We also extended previous work to show that these nanoparticles alter intestinal function," she said.
Supported by the CONACYT Fellowship, the National Institutes of Health, and the Binghamton University Research Foundation, the study also involved contributions from Elad Tako, Fabiola Moreno-Olivas, Nicole Martucci, and Zhongyuan Guo.
Titanium Dioxide Effects
For the study, the researchers exposed a culture model of small intestinal cells to the physiological equivalent of one meal's worth of the food additive for four hours to represent acute exposure and three meals' worth across five days to simulate chronic exposure.
Based on their observations, the researchers saw that titanium dioxide did not affect function in the cells of the small intestine in acute exposures. However, in the culture simulated to show chronic exposure, there was a drop in the number of microvilli.
With fewer of these absorptive projections, certain nutrients - particularly fatty acids, zinc, and iron - became harder to absorb, metabolism slowed, and the intestinal barrier weakened. Enzymatic functions were also negatively affected while inflammatory signals spiked.
In January, the French government ordered an inquiry into titanium dioxide after a study found that it has cancer links. Based on that study's results, chronic oral exposure to the food additive caused non-malignant carcinogenesis, which occurs as normal cells turn cancerous. This effect was observed in 40 percent of the rat subjects the researchers exposed to the food additive for 100 days.
Titanium dioxide is also known as E171.
Titanium Dioxide In Common Food Items
Generally considered safe by the U.S. Food and Drug Administration, titanium dioxide is difficult to avoid because it is in a lot of food items, such as bread, chocolate, donuts, skimmed milk, and candy. However, it is also used for white pigments in plastics, paper, and paints; it functions as the active ingredient for mineral-based sunscreens to block UV light; and it can be ingested in other commonly used products such as toothpaste.
A 2012 study examined 89 common food products and found that chewing gum, mayonnaise, and Twinkies all contain titanium dioxide. About 5 percent of the samples featured the food additive in nanoparticle form.
To avoid food items high in titanium dioxide, the researchers suggested avoiding processed food, especially candy.