Titanium dioxide in food and its safety gaps
What it found
Food-grade titanium dioxide is not completely inert after it is swallowed.
Animal and lab studies show some harmful changes, but the evidence in people is thin and uncertain.
What they found
Studies in people
Children take in the most
Estimates from several countries put children's intake higher than adults, in part because they eat more sweets and pastries relative to their body weight. In Europe, the highest average intake for children aged 3 to 9 was 0.9 to 8.8 mg per kg of body weight per day.
Animal and lab studies
Liver changes in animals
Several studies in mice and rats found liver effects after repeated oral doses of tiny titanium dioxide particles, including higher liver weight and signs of liver cell damage. These effects were seen with particles smaller than 100 nm, not with larger ones.
Young animals may be more at risk
A few studies in young rodents suggested they may be more susceptible to harmful effects than adults. For example, young rats given anatase particles for 30 days showed liver changes that were not seen in adult rats.
Gut and immune effects
In mice, titanium dioxide particles worsened colitis and increased markers of tumor progression in a colon cancer model. In rats, food-grade titanium dioxide accumulated in gut immune tissue and increased numbers of immune cells there.
Studies in people and animals
Little gets into the body
Most swallowed titanium dioxide leaves in the feces. In rats given a single dose, only about 0.6% reached the blood and organs after 1 hour, dropping to about 0.05% after 7 days. Human studies also found low but detectable levels in blood after swallowing.
Other findings
Tiny particles are present
Food-grade titanium dioxide always contains a fraction of tiny particles below 100 nm as a byproduct of manufacturing. Measurements of different samples found this nano-sized fraction ranged from about 10% to 36% of particles by number.
What the authors conclude
“The observation that TiO 2 particles cause at least some adverse reactions in experimental animals is disturbing because this material, including its unavoidable nano-scale byproducts, has been in use as food additive since 1966.”
Also in their conclusions
- They say that food-grade titanium dioxide particles are not totally inert after being swallowed.
- They note that the observation that these particles cause at least some adverse reactions in experimental animals is disturbing.
- They advise that the data gaps and uncertainties should be addressed before declaring food-grade titanium dioxide particles as generally safe.
How it was done
Titanium dioxide has been used in food for more than 50 years, but the authors say the risk assessment for it was never satisfactorily completed. They wanted to look at the data gaps and uncertainties in the studies used to judge its safety.
They reviewed published studies on titanium dioxide particles, including how the particles are made, how much people eat, how much is absorbed, and tests in animals, cells and people. They focused on studies where the particles had been checked for size.
What it can’t tell you
- Many of the animal studies were small, used different designs, or did not analyze statistics well, so their results are uncertain.
- It is not clear whether the titanium found in blood and tissues is in the form of whole particles or dissolved material.
- Animal studies cannot show what happens in people, and the human studies so far are few and short.
Who paid
- Funding
- Funded by Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung; Forschungskredit of the University of Zurich (from the PubMed record).
- Authors work at
- Institute of Food, Switzerland; University of Zurich-Vetsuisse, Switzerland
The paper
- Title
- Critical review of the safety assessment of titanium dioxide additives in food
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Winkler HC, Notter T, Meyer U, Naegeli H (2018). Critical review of the safety assessment of titanium dioxide additives in food. Journal of nanobiotechnology. doi:10.1186/s12951-018-0376-8Free full textPubMed 29859103DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error