When used in food specifically, titanium dioxide is known as an additive called E171 and can be found in products like candy, chocolate, coffee creamer, cake decorations, chewing gum and even vitamin supplements. E171 is often used as coloring additive in foods, to lend the processed item a natural whiteness and opacity — such as in Skittles candy, where it's used as a white base to help give the candies their signature bright, colorful hue.

Mexican researchers sought to evaluate the effects of E171 across a span of conditions in mice, including its influence on behavior, along with the effects on the colon and liver. The research, published in 2020 in the journal Food and Chemical Toxicology, showed that E171 promoted anxiety and induced adenomas, or noncancerous tumors, in the colon. They also found that E171 heightened goblet cells hypertrophy and hyperplasia, which is typically seen in asthma patients and triggered by smoking or external pollutants and toxins. They also noted mucins overexpression in the mice, which can be linked to cancer cell formation.