Toxic effects of the food additives titanium dioxide and silica on the murine intestinal tract: Mechanisms related to intestinal barrier dysfunction involved by gut microbiota.

•Food grade TiO2 micro-/nanoparticles and SiO2 nanoparticles can cause toxic effects to the murine intestine.•All three particles caused inflammatory damage to the intestine.•The particles altered the gut microbiota, especially mucus-associated bacteria.•Disruption of the intestinal mucus barrier and increased LPS production are key mechanisms.•Nano-TiO2 activated the intestinal PKC/TLR4/NF-κB signalling pathway.