Food additive in desserts alters gut microbiota in mice

A food scientist at the University of Massachusetts Amherst has found that a common food additive, recently banned in France but allowed in many other countries, can significantly alter gut microbiota in mice, causing inflammation in the colon and changes in protein expression in the liver. The findings could have implications in the food industry and on human health and nutrition according to Hang Xiao, Professor and Clydesdale Scholar of Food Science.

“The study confirmed a strong linkage between foodborne titanium dioxide nanoparticles (TiO₂ NPs) and adverse health effects,” said Professor Xiao. The research findings were published in Small, a peer-reviewed interdisciplinary journal that covers nanotechnology.

Gut microbiota, which refers to the diverse and complex community of microorganisms in the gut, plays a vital role in human health. An imbalance of gut microbiota has been associated with a range of health issues, including inflammatory bowel disease, obesity and cardiovascular disease.

Human exposure to foodborne TiO₂ NPs primarily comes from a food additive known as E171, which comprises different-sized particles of TiO₂ — including one-third or more that are nanoscale. E171, which makes products look whiter and more opaque, is found in desserts, lollies, beverages and gum, with E171 exposure much higher in US children than adults, one study found. Smaller than 100 nm, foodborne nanoscale particles may have unique physiological properties that cause concern.

“The bigger particles won’t be absorbed easily, but the smaller ones could get into the tissues and accumulate somewhere,” said Professor Xiao.

In the study, Professor Xiao and his team 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, two-thirds of whom are obese or overweight; the other group of mice was fed a low-fat diet. The mice on the 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. The nanosized particles caused more negative changes in both groups of mice,” said Professor Xiao.

The obese mice were also more susceptible to the adverse health effects of TiO₂ NPs, causing more damage in obese mice than in their non-obese counterparts. 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 determine the health impact of gut microbiota disrupted by TiO₂ NP, researchers conducted a faecal transplant study. Researchers gave mice antibiotics to clear out their original gut microbiota, then transplanted faecal 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,” said Professor Xiao.

The study also measured levels of TiO₂ in human stool samples, finding a wide range, with further research needed to determine the long-term (such as lifelong and multigenerational) exposure to TiO₂ NPs.

Image credit: ©stock.adobe.com/au/peshkova