Chewing gum and bread could be bad for your health, a new study reveals.
Long-term exposure to a popular food additive leaves the body more prone to infections, scientists claim.
Titanium dioxide, found in a variety of foods as E171, damages cell structures inside the intestines, research suggests.
And not only does this allow for more harmful bacteria to enter the digestive system, but it prevents some nutrients from being absorbed, reports DailyMail.
Researchers exposed a small intestinal cell model to the equivalent of a meal's worth of titanium oxide nanoparticles over four hours.
They also tested the same model with three meal's worth over five days - deemed chronic exposure.
But only those who had been repeatedly given the additive had any negative effects, according to the study by Binghamton University.
Chronic exposure was found to have an effect on the ability of intestinal cells called microvilli - designed to help absorb nutrients.
This was found to weaken their intestines, and made zinc, iron and fatty acids more difficult to absorb.
The ability to break food down was also negatively affected, the study published in the journal NanoImpact discovered.
Study co-author Professor Gretchen Mahler said: "Titanium oxide is a common food additive and people have been eating a lot of it for a long time.
"We were interested in some of the subtle effects and we think people should know about them."
Despite the findings, health experts are adamant that titanium dioxide is safe and claim ingestion is nearly unavoidable.
The compound is commonly used for white pigmentation in paints, paper and plastics.
It can enter the digestive system through toothpastes, as titanium dioxide is used to create abrasion needed for cleaning.
And it is also used in some chocolate to give it a smooth texture, in donuts to provide color, and in skimmed milks to make them look more appealing.
Professor Mahler added: "To avoid foods rich in titanium oxide nanoparticles you should avoid processed foods, and especially candy. That is where you see a lot of nanoparticles."