Australian researchers examined how titanium dioxide as a food additive affected gut microbiota in mice by orally administering it in drinking water. The study, published in the journal Frontiers in Nutrition in 2019, found the treatment could “alter the release of bacterial metabolites in vivo and affect the spatial distribution of commensal bacteria in vitro by promoting biofilm formation. We also found reduced expression of the colonic mucin 2 gene, a key component of the intestinal mucus layer, and increased expression of the beta defensin gene, indicating that titanium dioxide significantly impacts gut homeostasis.” The changes were then linked to colonic inflammation, along with a higher expression of inflammatory cytokines, which are signal proteins that help with regulation. The researchers concluded that titanium dioxide “impairs gut homeostasis which may in turn prime the host for disease development.”

What's the Verdict?

In a 2017 study published in Scientific Reports, researchers exposed rats to human-relevant levels of E171 to examine the effects of intestinal inflammation and carcinogenesis. They saw that “a 100-day E171 treatment promoted colon microinflammation and initiated preneoplastic lesions while also fostering the growth of aberrant crypt foci in a chemically induced carcinogenesis model.” They continued: “Stimulation of immune cells isolated from Peyer’s Patches [which are clusters of lymphoid follicles found in the intestine] showed a decrease in Thelper (Th)-1 IFN-γ secretion, while splenic Th1/Th17 inflammatory responses sharply increased,” researchers wrote. “A 100-day titanium dioxide treatment promoted colon microinflammation and initiated preneoplastic lesions.” The scientists concluded: “These data should be considered for risk assessments of the susceptibility to Th17-driven autoimmune diseases and to colorectal cancer in humans exposed to TiO2 from dietary sources.”