An inorganic chemical, titanium dioxide is used as a dye to help products achieve a certain appearance, including whitening a product. Some experts and publications have described it as being akin to a paint primer that's used before the color is added to food in order to give products a uniform shine. Its presence is common in many items beyond Skittles including coffee creamers, cake mixes, and chewing gum. It's also used for pigment and in cosmetics manufacturing.

In some studies, E171 was given to animals in drinking water without the stabilizers that keep E171 suspended in the liquid. Without stabilizers, E171 can settle and prevent the ingredient from combining with surrounding ingredients.