Titanium dioxide
A white mineral pigment used to whiten and brighten food. Banned in the EU in 2022 after regulators could not rule out DNA damage; still permitted in Great Britain.
The EU's food safety authority concluded that DNA damage from titanium dioxide particles could not be ruled out, and set no safe daily intake. The additive contains a fraction of nano-sized particles that persist in the gut. Chewing gum and cake decorations carry the highest concentrations.
What is it?
Titanium dioxide is a white mineral pigment (TiO2) mined from natural ores and refined into a fine powder. Food-grade E171 contains both micro-sized and nano-sized particles; studies report that roughly 20 to 30 percent of constituent particles by number fall below 100 nanometres, though these nanoparticles represent less than 1 percent of the material by mass.
What does it do?
It scatters light across the visible spectrum, making foods appear brighter, whiter, and more opaque. It contributes no flavour, no nutritional value, and no preservation effect. It is used purely as a colouring agent.
Where you will see it
Chewing gum and mints carry the highest concentrations. Other common sources include cake icing, sugar-coated sweets and confectionery, white chocolate coatings, cake decorations and fondant, sauces including white sauce and mayonnaise, dairy-free drinks and plant-based dairy alternatives, food supplements in tablet or capsule form, and processed savoury products. On a UK label it appears as E171 or as titanium dioxide.
What the science says
EU safety authority concluded DNA damage could not be ruled out
In May 2021 EFSA's Panel on Food Additives and Flavourings reviewed more than 11,000 publications and concluded that genotoxicity, meaning the ability to damage DNA, could not be excluded. Because EFSA could not determine a dose below which the risk disappeared, it was unable to set a daily intake limit. That conclusion led directly to the EU ban in January 2022. EFSA did not conclude that E171 is definitively genotoxic, but the unresolved uncertainty was enough to remove authorisation.
EFSA concluded that a genotoxicity concern for E171 titanium dioxide could not be ruled out, and no acceptable daily intake could be established.
Based on the EFSA 2021 opinion, the European Commission banned E171 from all food use via Commission Regulation (EU) 2022/63, effective 7 February 2022, with transition ending 7 August 2022.
UK's Committee on Toxicity reached a different conclusion in 2024
The UK's Committee on Toxicity (COT) published its own assessment in October 2024 after reviewing the same body of evidence plus newer studies. It found little evidence that food-grade titanium dioxide causes DNA damage through oral exposure, particularly with micro-sized particles. The COT set a health-based guidance value of 10 mg per kilogram of body weight per day and concluded that risk to health from typical UK dietary exposure was unlikely. The UK and the EU have reached genuinely opposite conclusions from overlapping evidence.
The UK Committee on Mutagenicity found little evidence in the literature to suggest genotoxicity concern from oral exposure to food-grade TiO2, particularly for micro-sized particles.
COT established a health-based guidance value of 10 mg per kilogram body weight per day, derived from an extended one-generation reproductive toxicity study showing no adverse effects at 1,000 mg per kilogram body weight per day.
At 95th percentile exposure, children and adolescents may exceed the COT's guidance value by 1.3 to 2.6 times, though COT noted that actual intakes are likely lower than calculated maxima.
Gut inflammation and pre-cancerous lesions: animal evidence that has not been replicated
A 2017 rat study by Bettini et al. reported that titanium dioxide particles increased intestinal inflammation and triggered early pre-cancerous changes called aberrant crypt foci in the colon. The study used particles dispersed in drinking water at human-relevant doses. However, multiple subsequent feeding studies at substantially higher doses did not reproduce those findings, and the COT concluded there was no evidence that E171 induces aberrant crypt foci. The original signal has not been confirmed.
Bettini et al. reported that food-grade TiO2 in drinking water promoted intestinal inflammation and aberrant crypt foci in rats after 100 days at 10 mg per kilogram body weight per day.
Subsequent feeding studies at doses orders of magnitude higher than Bettini et al. did not replicate the aberrant crypt foci finding; the COT concluded TiO2 did not induce them.
Gut microbiome disruption in animal and laboratory studies
Multiple animal studies have found that regular ingestion of titanium dioxide alters gut bacteria, reducing populations of beneficial species such as Bifidobacterium and Lactobacillus and increasing markers of intestinal inflammation. In vitro studies also show that E171 changes how the gut lining responds to bacterial signals. These are animal and laboratory findings; whether the same effects occur at food-relevant doses in humans has not been established.
In mouse studies, 8 weeks of dietary TiO2 at 0.1 percent by weight caused microbiota dysbiosis characterised by increased Firmicutes, decreased Bacteroidetes, and reduced Bifidobacterium and Lactobacillus.
An in vitro colon model study found that food-grade E171 altered gut microbial metabolic activity and reduced butyrate production, a marker of intestinal health.
IARC classifies titanium dioxide as a possible carcinogen by inhalation, not by ingestion
In 2006 the International Agency for Research on Cancer (IARC) classified titanium dioxide as Group 2B, possibly carcinogenic to humans. This classification was based on animal studies showing lung tumours in rats that inhaled high concentrations of titanium dioxide dust in industrial settings. IARC's 2006 evaluation did not address food ingestion. The Group 2B classification for oral ingestion of food-grade E171 has not been established by IARC.
IARC classified titanium dioxide as Group 2B, possibly carcinogenic to humans, based on sufficient evidence of carcinogenicity by inhalation in rats and inadequate evidence in humans. This classification applies to inhaled dust.
International regulators disagree with the EU ban
Health Canada, Food Standards Australia New Zealand, the US Food and Drug Administration, and the UK Food Standards Agency all reviewed the same body of evidence and did not adopt the EFSA conclusion. A 2024 review in Frontiers in Toxicology, authored by a toxicologist, argued that EFSA's genotoxicity analysis was flawed and that positive findings in studies were driven by cytotoxicity and oxidative stress rather than direct DNA damage. The scientific disagreement between regulators is genuine and remains unresolved.
Health Canada (2022), FSANZ (2022), the US FDA (2024) and the UK FSA did not adopt the EFSA genotoxicity conclusion and continue to permit E171 in food.
An independent expert panel reviewing 192 genotoxicity datasets found only 34 met quality criteria; positive results were attributed to high cytotoxicity and oxidative stress rather than direct DNA damage.
Where it stands with the regulators
Who should be careful
Children are the highest-exposed group because they eat more confectionery, chewing gum, and cake decorations relative to their body weight. The UK COT found that high-end consumers among toddlers and children may exceed the guidance value. Anyone wanting to reduce exposure should check ingredient labels for E171 or titanium dioxide on chewing gum, sugar-coated sweets, iced confectionery, white sauces, and food supplement tablets. People in Northern Ireland: food manufactured there after 7 August 2022 should not contain E171.
The honest read
This is one of the most contested food additive decisions in recent memory. The EU banned E171 in 2022 after its food safety authority concluded that DNA damage from the particles could not be ruled out and no safe intake level could be set. The UK, Canada, Australia, New Zealand, and the US all reviewed the same body of evidence and kept the additive authorised, arguing the genotoxicity concern was not well-founded and that absorption from the gut is negligible. The UK's own expert committee completed a fresh assessment in 2024 and concluded risk from typical UK diets was unlikely, though children eating large amounts of chewing gum and confectionery may approach or exceed its guidance value. Animal studies have raised concerns about gut bacteria disruption and intestinal inflammation; those signals have not been confirmed in humans at dietary doses. A 2017 rat study linking E171 to pre-cancerous colon changes has not been replicated at higher doses. The core disagreement, whether nano-particle fractions in food-grade E171 can damage DNA in the cells lining the gut, has not been resolved. Two major regulatory systems, using the same science, have reached opposite conclusions. That disagreement is the honest read.
Related additives
Common questions
Is E171 banned in the UK?
Not in Great Britain. E171 titanium dioxide is still on the UK FSA's approved-additives list and can be used in food products sold in England, Scotland and Wales. It is banned in Northern Ireland, which follows EU food law under the Windsor Framework. The EU banned E171 from all food use in August 2022 after its food safety authority could not rule out DNA damage.
Why did the EU ban E171 but the UK kept it?
The EU's food safety authority (EFSA) published an opinion in 2021 concluding that a genotoxicity concern, meaning potential for DNA damage, could not be excluded, so no safe daily intake could be set. The UK's Committee on Toxicity reviewed the same evidence and additional studies, concluded the genotoxicity concern was not well supported for oral ingestion, and set a health-based guidance value instead. Health Canada, Australia, New Zealand, and the US FDA also disagreed with EFSA's conclusion. The scientific disagreement is genuine and unresolved.
What foods contain E171?
The highest concentrations appear in chewing gum and mints, cake icing and fondant, sugar-coated confectionery, white chocolate coatings, and cake decorations. It is also used in sauces, dairy-free drinks, plant-based alternatives, food supplement tablets, and some desserts and bakery products. On the label it appears as E171 or titanium dioxide.
Is E171 vegan?
Titanium dioxide itself is a mineral with no animal-derived ingredients. However, the foods that commonly contain E171, such as white chocolate, some confectionery coatings, and certain sweets, may contain milk, gelatine, or other animal products. Check the full ingredient list rather than assuming E171 is the only relevant ingredient.
Sources
- EFSA Panel on Food Additives and Flavourings: Safety assessment of titanium dioxide (E171) as a food additive, EFSA Journal 2021;19(5):e06585
- UK Committee on Toxicity: Statement on the Safety of Titanium Dioxide (E171) as a Food Additive (2024)
- UK Committee on Toxicity: Lay Summary, COT Statement on E171 (2024)
- UK FSA Approved Additives and E Numbers
- Commission Regulation (EU) 2022/63 withdrawing authorisation of titanium dioxide as a food additive
- Food Safety Authority of Ireland: EFSA Opinion on E171 no longer considered safe
- Bettini S et al.: Food-grade TiO2 impairs intestinal and systemic immune homeostasis, initiates preneoplastic lesions and promotes aberrant crypt development in the rat colon, Scientific Reports 2017;7:40373
- Warheit D: Safety of titanium dioxide (E171) as a food additive for humans, Frontiers in Toxicology 2024;5:1333746
- IARC Monographs Volume 93: Carbon Black, Titanium Dioxide, and Talc (2006/2010)
- COT Exposure Assessment: Statement on the Safety of Titanium Dioxide (E171) as a Food Additive
Aaron Keen is the founder of NutraSafe. He researches and writes every additive entry himself, from the primary sources. About the research →
This is a guide, not medical advice. If an additive affects you, speak to your GP or a dietitian.
See this on every food you scan
NutraSafe reads the label and puts every additive into plain English, with the source, right in the app.
Get NutraSafe on the App Store