Common food additive may cause adverse health effects in mice

A common food additive, recently banned in France but allowed in the United States and many other countries, was found to significantly alter gut microbiota in mice, causing inflammation in the colon and changes in protein expression in the liver, according to research published in Small, a weekly, peer-reviewed journal that covers nanotechnology.

“I think our results have a lot of implications in the food industry and on human health and nutrition,” said lead author Hang Xiao, a professor at the University of Massachusetts Amherst, in a university press release. “The study confirmed a strong linkage between foodborne titanium dioxide nanoparticles (TiO₂ NPs) and adverse health effects.”

Human exposure to foodborne TiO₂ NPs comes primarily from a food additive known as E171, which is made up of different-size particles of TiO₂, including one-third or more that are nanoscale. E171, which makes products look whiter and more opaque, is found in such food as desserts, candy, beverages, and gum. E171 exposure is two to four times higher in U.S. children than in adults, one study has found.

The researchers fed either E171 or TiO₂ NPs to two populations of mice as part of their daily diet. One population was fed a high-fat diet similar to that of many Americans, and the other group of mice was fed a low-fat diet. The mice fed a high-fat diet eventually became obese, while the mice on the low-fat diet did not.

“In both the non-obese mice and obese mice, the gut microbiota was disturbed by both E171 and TiO₂ NPs,” said Xiao. “The nanosized particles caused more negative changes in both groups of mice.” Moreover, the obese mice were more susceptible to the adverse effects of TiO₂ NPs, causing more damage in obese mice than in non-obese ones.

The researchers found TiO₂ NPs decreased cecal levels of short-chain fatty acids, which are essential for colon health, and increased pro-inflammatory immune cells and cytokines in the colon, indicating an inflammatory state.

To evaluate the direct health impact of gut microbiota disrupted by TiO₂ NP, the researchers conducted a fecal transplant study. They gave mice antibiotics to clear out their original gut microbiota and then transplanted fecal bacteria from the TiO₂ NP-treated mice to the antibiotic-treated mice. “The results support our hypothesis that including TiO₂ NPs in the diet disrupts the homeostasis of the gut microbiota, which in turn leads to colonic inflammation in the mice,” concluded Xiao.