A  2023 study published in the journal Environmental Research, scientists examined the effect of titanium dioxide nanoparticles on important gut bacteria in mice. Their results showed “the growth inhibitory effects could be associated with cell membrane damage caused by titanium dioxide nanoparticles to the bacterial strains. Metabolomics analysis showed that TiO2 NPs caused alterations in multiple metabolic pathways of gut bacteria, such as tryptophan and arginine metabolism, which were demonstrated to play crucial roles in regulating gut and host health.” The researchers also found that four different neuroprotective metabolites “were significantly reduced” in urine and in vitro bacteria and vivo urine samples. The researchers concluded: “Increasing evidence implies that the gut microbiome plays a profound role in regulating host metabolism. Our results illustrated that TiO2 NPs hindered the growth of four beneficial gut bacterial strains.”

Wegman’s puts titanium dioxide in its Original Macaroni and Cheese. Campbell’s Healthy Request Chunky Chicken Corn Chowder has it, as does Food Club’s Chunky New England Clam Chowder. Marzetti uses the color agent to brighten its Cream Cheese Fruit Dip. Dairy products usually don’t need titanium dioxide to look white, but Kroger has decided to add titanium dioxide to its Fat Free Half-and-Half. And titanium dioxide isn’t only in especially white or brightly colored foods: Little Debbie adds it to Fudge Rounds and many other products. According to the Food Scores database maintained by Environmental Working Group, more than 1,800 brand-name food products have titanium dioxide on their ingredients list. That said, it can still lurk as an unspecified “artificial color,” or labels might simply say “color added.”

Titanium dioxide (TiO₂) is commonly applied to enhance the white colour and brightness of food products. TiO₂ is also used as white pigment in other products such as toothpaste. A small fraction of the pigment is known to be present as nanoparticles (NPs). Recent studies with TiO₂ NPs indicate that these particles can have toxic effects. In this paper, we aimed to estimate the oral intake of TiO₂ and its NPs from food, food supplements and toothpaste in the Dutch population aged 2 to over 70 years by combining data on food consumption and supplement intake with concentrations of Ti and TiO₂ NPs in food products and supplements. For children aged 2-6 years, additional intake via ingestion of toothpaste was estimated. The mean long-term intake to TiO₂ ranges from 0.06 mg/kg bw/day in elderly (70+), 0.17 mg/kg bw/day for 7-69-year-old people, to 0.67 mg/kg bw/day in children (2-6 year old). The estimated mean intake of TiO₂ NPs ranges from 0.19 μg/kg bw/day in elderly, 0.55 μg/kg bw/day for 7-69-year-old people, to 2.16 μg/kg bw/day in young children. Ninety-fifth percentile (P95) values are 0.74, 1.61 and 4.16 μg/kg bw/day, respectively. The products contributing most to the TiO₂ intake are toothpaste (in young children only), candy, coffee creamer, fine bakery wares and sauces. In a separate publication, the results are used to evaluate whether the presence of TiO₂ NPs in these products can pose a human health risk.

Toxic effects of TiO₂ NPs on aquatic organisms