Impact of Food Additive Titanium Dioxide on Gut Microbiota Composition, Microbiota-Associated Functions, and Gut Barrier: A Systematic Review of In Vivo Animal Studies

Abstract

Background: Titanium dioxide (TiO2) is used as a food additive in pastries, sweets, and sauces. It is recognized as safe by food safety authorities, but in recent years, governments and scientists have raised concerns about its genotoxicity. This systematic review aims to assess the potential associations between food TiO2 exposure and microbiota composition and functions. Methods: A systematic literature search was performed up to December 2020 in PubMed, Web of Science, and Scopus databases. The PRISMA guidelines followed. The risk of bias was assessed from ARRIVE and SYRCLE tools. Results: A total of 18 animal studies were included (n = 10 mice, n = 5 rats, n = 2 fruit flies, n = 1 silkworm). Studies varied significantly in protocols and outcomes assessment. TiO2 exposure might cause variations in abundance in specific bacterial species and lead to gut dysfunctions such as a reduction in SCFAs levels, goblet cells and crypts, mucus production, and increased biomarkers of intestinal inflammation. Conclusions: Although the extrapolation of these results from animals to humans remains difficult, this review highlights the key role of gut microbiota in gut nanotoxicology and stimulates discussions on the safe TiO2 use in food and dietary supplements. This systematic review was registered at PROSPERO as CRD42020223968.

Effect of Two Soybean Varieties Treated with Different Heat Intensities on Ileal and Caecal Microbiota in Broiler Chickens

“…One explanation for the high percentage of Firmicutes seen in this study might be the presence of titanium dioxide (TiO 2 ), used as an inert digestibility marker in all finisher diets. This assumption agrees with other studies also indicating an increased abundance of Firmicutes in rodents in the presence of TiO 2 [49]. Although the effects of TiO 2 nanoparticles on gut microbiota and its metabolism have been discussed extensively, the precise mechanisms of these effects are still not elucidated [50].…”

Analysis of Research Status and Development Trend of Nanotoxicology of Liliaceae Medicinal Plants

“…There are very few valuable research results, and there are still many uncertain ecological security issues to be further investigated. Based on the summary of relevant research at home and abroad, the source of nanomaterials, the way of entering the environment, environmental behavior, ecotoxicological research status, and the contents to be further investigated were briefly reviewed [ 3 ]. The development process of nanotechnology is shown in Figure 3 .…”

Food-Grade Titanium Dioxide Induces Toxicity in the Nematode Caenorhabditis elegans and Acute Hepatic and Pulmonary Responses in Mice

“…Recent studies have found evidence of downstream events outside the gastrointestinal tract, sharing the same mechanism of absorption through capillaries and vessels, entering the circulatory system with subsequent systemic diffusion [ 32 , 49 , 50 , 51 ]. Therefore, in the present study, we investigated the potential effects of single systemic over-exposure to E171 in immunocompetent healthy mice.…”