When E171 isn’t combined with other ingredients and administered in water, some studies suggest that under these artificial conditions, E171 may be processed differently in the body resulting in some biological changes in experimental animals that are poorly understood.

Titanium dioxide particles help light scatter and reflect, Kelly Johnson-Arbor, MD, a medical toxicology physician at the National Capital Poison Center, told Health. Because of that, we often use it as a whitening agent.