Titanium dioxide nanoparticles are commonly used in dietary supplements and cosmetic products.  A new study confirms that ingestion of titanium dioxide may cause chronic damage.  The study shows that titanium dioxide nanoparticles can cross both the regular ileum epithelium and follicle-associated epithelium in vivo and ex vivo, and change their paracellular permeability. Authors claim that titanium dioxide "would induce epithelium impairment, and would persist in gut cells where they would possibly induce chronic damage." Some dietary supplements companies have discontinue using titanium dioxide in their products.   At this time, silica is still very commonly used in dietary supplements, cosmetic products, and processed foods.  Studies show even crystalline silica is not as safe as expected.

Brun E, Barreau F, Veronesi G, Fayard B, Sorieul S, Chanéac C, Carapito C, Rabilloud T, Mabondzo A, Herlin-Boime N, Carrière M.  Titanium dioxide nanoparticle impact and translocation through ex vivo, in vivo and in vitro gut epithelia.   Part Fibre Toxicol. 2014 Mar 25; 11:13.