TiO2 comes in many different forms. However, only a few of these forms are considered food-grade (acceptable to be added to food). Many studies that raised concern about the safety of TiO2, including the concern for genotoxicity, used forms of TiO2 that are not considered acceptable for use in food and have different properties than food-grade TiO2. Other studies did use food-grade TiO2, but took steps to break the material down into smaller particles than what would normally be found in food.
In a 2022 study published in the Journal of Hazardous Materials, scientists wanted to examine the effects of titanium dioxide as a food additive on atherosclerosis in mice. (Atherosclerosis refers to a hardening of the arteries.) Researchers fed mice 40 mg/kg of the food additive every day for 4 months, and found that it not only altered gut microbiota but also led to a significantly increased atherosclerotic lesion area, especially in animals that consumed a high-choline western diet (HCD).