Titanium dioxide is the most widely used whitening pigment in the world and has been linked to adverse health effects, particularly genotoxicity and intestinal inflammation. It is applied as food coloring and a whitening agent to a wide variety of foods, including chewing gum, cakes, candies, breads and ice cream. As a pigment, it is called Pigment White 6 (PW6), titanium white, or CI 77891. When used as a food coloring, it is known as E171.
Because of health risks, France banned titanium dioxide as a food additive in 2020. Two years later the European Union also banned titanium dioxide as a food additive.
But in the U.S., titanium dioxide is found all over the grocery shelves. (See Recent Policy Changes at the end of this article.) Candy like Skittles, Starbursts, and Jell-O, gum like Trident White peppermint gum and Mentos Freshmint Gum, cake products like Duncan Hines Creamy Vanilla Frosting, and Nabisco Chips Ahoy! cookies are just a few of the myriad food items that contain the additive.
A significant body of research, mostly from rodent models and in vitro studies, has linked titanium dioxide with health risks related to the gut, including intestinal inflammation, alterations to the gut microbiota, neurotoxicity and more. It is classified by the International Agency for Research on Cancer (IARC) in Group 2B, as possibly carcinogenic to humans. As a food additive, titanium dioxide and its nanoparticles in particular have been associated with DNA damage and cell mutations, which in turn, have potential to cause cancer.
Nanoparticles
Nanoparticles are ultrafine particles between 1 to 100 nanometers in diameter. (To put this in perspective, the average human hair is around 80,000 nanometers thick.) Because of their size, which can be engineered and manipulated at the atomic or molecular level, nanoparticles exhibit unique physical, chemical, and biological properties.
Titanium dioxide is one of the most commonly produced nanoparticles in the world. Its nanoparticles are commonly found in a wide-range of consumer goods, including cosmetics, sunscreens, paints and colorings, ceramics, glass, textiles, construction materials, medicine, food, food packaging, and more. In Europe, cosmetic companies are required to label products that contain nanoparticles. In the U.S., companies are not.
Over the last several years, nanoparticles have come under scrutiny for adverse health effects. With the rise of nanotechnology, research in recent years has shown the dangers of titanium dioxide (TiO2) nanoparticles, and their genotoxicity, which refers to a chemical agent’s ability to harm or damage DNA in cells, thus potentially causing cancer.
In general, nanoparticles have been shown to accumulate in the body, particularly in organs in the gastrointestinal tract, along with the liver, spleen, and capillaries of the lungs. Research published in Scientific Reports found a link between immune system disorders and the absorption of titanium dioxide nanoparticles.
26 Studies of Titanium Dioxide as a Food Additive Suggest Health Dangers
Genotoxicity and Cytotoxicity: Numerous studies have linked titanium dioxide to genotoxicity and cytotoxicity. Genotoxicity refers to a chemical’s potential to cause DNA damage, which can, in turn, lead to cancer. Cytotoxicity is a general term that refers to a characteristic of being harmful to cells.
Nanotoxicology (2023) — French researchers studied how and where E171 nanoparticles enter the bloodstream. The research showed that the E171 nanoparticles absorbed quickly through the mouth and then into the bloodstream, before damaging DNA and hindering cell regeneration.
Scientifica (Cairo) (2016) — Egyptian researchers examined the effects of titanium dioxide nanoparticles on the organs of mice, and wrote: “The present study concluded that TiO2NPs [titanium dioxide] is genotoxic and mutagenic to brain tissue which in turn might lead to Alzheimer’s disease incidence.”
Food and Chemical Toxicology (2022) — Scientists tested the genotoxicity and the intracellular reactive oxygen species induction of three different TiO2 nanomaterials, and found an indicator of cancer risk for all the tested TiO2 nanomaterials. They concluded the results showcase “evidence of concern” regarding titanium dioxide used as a food additive.
Toxicology (2022) — Researchers examined the effects of exposing human colon cancer cell line (HTC116) to titanium dioxide food additives in vitro. They found “E171 was accumulated in the cells after 24 hours of exposure, increasing granularity and reactive oxygen species, inducing alterations in the molecular pattern of nucleic acids and lipids, and causing nuclei enlargement, DNA damage and tubulin depolymerization.”
5. NanoImpact(2022) — Researchers evaluated the latest research related to genotoxic effects of titanium dioxide through in vivostudies and in vitro cell tests. They summarized the results by stating TiO2 nanoparticles “could induce genotoxicity prior to cytotoxicity,” and “are likely to be genotoxic to humans.”
Inflammation of the Intestines: Animal studies have shown that, when consumed as a food additive, titanium dioxide can induce intestinal inflammation.
Nanotoxicology (2019) — Researchers wrote: “Significant accumulation of titanium was observed in the liver and intestine of E171-fed mice. Overall, [this] indicates that the risk for human health associated with dietary exposure to E171 needs to be carefully considered.”
Animal studies have shown that, when consumed as a food additive, titanium dioxide can induce intestinal inflammation.
Journal of Agricultural and Food Chemistry(2019) — Researchers wrote: “Dietary TiO2 nanoparticles could interfere with the balance of the immune system and dynamic of gut microbiome, which may result in low-grade intestinal inflammation and aggravated immunological response to external stimulus, thus introducing potential health risk.”
Particle and Fibre Technology(2021) — Scientists evaluated whether Ti02 particles contributed to the development and/or exacerbation of irritable bowel disease. “Data indicate that TiO2 is able to alter the four compartments of IBF [irritable bowel function] and to induce a low-grade intestinal inflammation associated or not with pre-neoplastic lesions.”
Neurotoxicity
Alzheimer’s and Dementia (2025) — This study provides prime evidence that nanoparticles of titanium dioxide (used in food and cosmetics) and Carbon Black (found in rubber and pigments) bind to a specific receptor in neurons, corrupting its signaling and causing oxidative stress, inflammation, and overproduction of toxic amyloid-beta peptides, which are key markers of Alzheimer’s disease.
Nanoscale Research Letters (2015) — After reviewing dozens of studies on how titanium dioxide nanoparticles interact with the brain, the scientists concluded: “Long-term or chronic exposure to TiO2 nanoparticles could potentially lead to the gradually increased Ti contents in the brain, which may eventually induce impairments on the neurons and glial cells and lead to CNS dysfunction as a consequence.”
Archives of Toxicology (2020) — Scientists found “the richness and evenness of gut microbiota were remarkably decreased and the gut microbial community compositions were significantly changed” in the titanium dioxide group when compared with the control group in two groups of test mice over a one month testing period.
Journal of Trace Elements in Medicine and Biology (2020) — Researchers conducted an in vitro experiment to analyze the effects of TiO2 nanoparticles on a human neuroblastoma (SH-SY5Y) cell line. The results showed that exposure to the nanoparticles “induced ROS generation in a dose dependent manner, with values reaching up to 10 fold those of controls.”
Promotion of Obesity-related Metabolic Disorders
Environmental Pollution (2023) — Researchers examined E171 as a possible factor promoting obesity-related metabolic disorders. The study authors discovered recurrent changes in the gut microbiota composition when exposed to titanium dioxide nanoparticles, and concluded “foodborne TiO2 nanoparticles are an endocrine disruptor-like chemical promoting obesity-related disorders.”
Colorectal Tumors and Preneoplastic Lesions
Food and Chemical Toxicology (2016) — Researchers investigated whether titanium dioxide exposure led to an increase in colorectal tumor creation in mice. By measuring tumor progression markers, the researchers found that mice given titanium dioxide experienced enhanced tumor formation in the distal colon. There was also a decrease of cells that act as a protective barrier in the colon. The researchers wrote: “These results suggest that E171 could worsen pre-existent intestinal diseases.”
Scientific Reports (2017) —Researchers exposed rats to human-relevant levels of E171 to examine the effects of intestinal inflammation and carcinogenesis. They saw that “a 100-day E171 treatment promoted colon microinflammation and initiated preneoplastic lesions while also fostering the growth of aberrant crypt foci in a chemically induced carcinogenesis model.”
Alterations in Gut Microbiota: Research has shown that, when ingested as a food additive, titanium dioxide and its nanoparticles can impact, alter, and/or damage important protective bacteria in the gut, along with the metabolic pathways of gut bacteria.
Food and Chemical Toxicology (2025) — Titanium dioxide nanoparticles appear to interfere with how the gut senses nutrients from food in the body, and how it produces and releases key hormones involved in digestion and blood sugar level control. When the body can’t control blood sugar properly, it can lead to type 2 diabetes and obesity by making it harder to use insulin and easier to store fat.
Titanium dioxide nanoparticles appear to interfere with how the gut senses nutrients from food in the body, and how it produces and releases key hormones involved in digestion and blood sugar level control.
Environmental Research (2023) — Scientists examined the effect of titanium dioxide nanoparticles on important gut bacteria in mice. The researchers concluded: “Increasing evidence implies that the gut microbiome plays a profound role in regulating host metabolism. Our results illustrated that TiO2 NPs hindered the growth of four beneficial gut bacterial strains.”
Frontiers in Nutrition (2019) — Australian researchers examined how titanium dioxide as a food additive affected gut microbiota in mice by orally administering it in drinking water. The study found that titanium dioxide significantly “impairs gut homeostasis which may in turn prime the host for disease development.”
European Journal of Nutrition (2020) — Researchers examined the effects of several food additives, including titanium dioxide, along with artificial sweeteners and cleaning products by testing the fecal samples of 13 people. The growth of the bacterium species belonging to C. leptum, which has been shown to decreasein patients with inflammatory bowel disease, “significantly decreased in the presence of … titanium dioxide”.
Environmental Toxicology and Pharmacology (2020) — Researchers examined the effects of food additives titanium dioxide and silica on the intestinal tract by grouping and feeding mice three different food-grade particles — micro-TiO2, nano-TiO2, and nano-SiO2. With all three groups, researchers observed changes in the gut microbiota, but the nano-TiO2 displayed the most pronounced changes. These findings will raise awareness of toxicities associated with the use of food-grade TiO2 and SiO2.”
Increased Severity of Ulcerative Colitis
Particle and Fibre Toxicology (2023) — By creating an ulcerative colitis disease model, researchers found that titanium dioxide nanoparticles significantly increased the severity of colitis, prolonging the ulcerative colitis course and inhibiting ulcerative colitis recovery.
Atherosclerosis
Journal of Hazardous Materials (2022) Scientists examined the effects of titanium dioxide as a food additive on atherosclerosis in mice, and found that it not only altered gut microbiota but also led to a significantly increased atherosclerotic lesion area, especially in animals that consumed a high-choline western diet (HCD).
Promotion of Noncancerous Tumors
Food and Chemical Toxicology (2020) – Mexican research showed that E171 promoted anxiety in mice, and induced adenomas, or noncancerous tumors, in the colon. They also noted mucins overexpression in the mice, which can be linked to cancer cell formation.
Breathing Problems in Offspring
Particle and Fibre Technology (2022) — Examining the impact of maternal exposure to titanium dioxide nanoparticles in newborn offspring mice, researchers found that “a chronic exposure to TiO2 NPs during pregnancy alters the respiratory activity of offspring, characterized by an abnormally elevated rate of breathing,” and the ability for neural circuitry to effectively adjust breathing rates was impaired.
Human exposure begins in utero via maternal-fetal transfer and continues after birth by breastfeeding. Children are then chronically re-exposed due to their food preferences.
Decreased Vitamin D Bioaccessibility
Journal of Agricultural and Food Chemistry (2021) — Chinese researchers examined the impact of E171 on lipid digestion and vitamin D3 bioaccessibility in a simulated human gastrointestinal tract model. They found vitamin D’s bioaccessibility — becoming available for absorption — “significantly decreased from 80% to 74%” with the addition of E171.
Exposure To Titanium Dioxide In Utero and in Breastfeeding Children
Archives of Toxicology (2022) — Researchers found that the ingestion of E171 is a “a definite health risk for consumers and their progeny.” After reviewing dozens of in vivo, ex vivo and in vitro studies on the toxicity of E171, the researchers wrote that two facts must be noted: “First, reprotoxicity studies show that animals of both sexes are impacted by the toxicity of these nanoparticles, underlining the importance of conducting in vivo studies using both male and female animals. Second, human exposure begins in utero via maternal-fetal transfer and continues after birth by breastfeeding. Children are then chronically re-exposed due to their food preferences. To be relevant to the human in vivo situation, experimental studies should therefore consider nanoparticle exposure with respect to the age or life period of the studied population.”
Recent Policy Changes In Regard To Titanium Dioxide
EU BAN ON TITANIUM DIOXIDE: The European Commission banned titanium dioxide as a food additive in the EU in 2022 after the European Food Safety Authority (EFSA) conducted an updated safety assessment of E171 and concluded the panel could not eliminate concerns about its genotoxicity.
EFSA SCIENTIFIC CONCLUSION ON E171: Following a request for assessment in 2020 by the EU, the European Food Safety Authority (EFSA) assessed E171, particularly for its genotoxicity. In 2022, the agency deemed the food additive no longer safe for use.
Prof. Maged Younes, Chair of EFSA’s expert Panel on Food Additives and Flavourings (FAF), wrote of the decision: “Taking into account all available scientific studies and data, the Panel concluded that titanium dioxide can no longer be considered safe as a food additive. A critical element in reaching this conclusion is that we could not exclude genotoxicity concerns after consumption of titanium dioxide particles. After oral ingestion, the absorption of titanium dioxide particles is low, however they can accumulate in the body.”
Prof. Matthew Wright, chair of EFSA’s working group on E171, noted: “Although the evidence for general toxic effects was not conclusive, on the basis of the new data and strengthened methods we could not rule out a concern for genotoxicity and consequently we could not establish a safe level for daily intake of the food additive.”
FDA’S RESPONSE: Following the EU’s ban on E171, the Food and Drug Administration (FDA) told the Guardian that, based on current evidence, titanium dioxide as a food additive is safe. “The available safety studies do not demonstrate safety concerns connected to the use of titanium dioxide as a color additive.”
Currently, titanium dioxide as a food additive is classified as GRAS, or “generally recognized as safe.”
The FDA has not updated its general guidance on safety assessments since 2007. Within that time, there has been a significant increase in research on the confluence of toxicology, nanotechnology and human health. The EU updates its guidance regularly with new science available to offer proper safety assessments, with its most recent update published in 2021.
As for titanium dioxide, the FDA approved titanium dioxide for use as a food additive in 1966. The last time the agency reviewed the additive’s safety, according to the Guardian, was in 1973.
STATES LOOKING TO BAN TITANIUM DIOXIDE AS A FOOD ADDITIVE: In 2023, California and New York proposed banning several food additives that are banned in Europe but legal in the United States. Titanium dioxide was among the five proposed to be banned, but in September, the additive was removed from the list of additives from the California ban list.
AUSTRALIA AND NEW ZEALAND REVIEW OF TIO2: In 2022, a year after the EFSA recommended against the use of E171, the Food Standards Australia New Zealand (FSANZ) conducted its own reassessment of titanium dioxide as a food additive. The agency concluded that titanium dioxide was indeed safe to use as a food additive. The United Kingdom and Canada came to similar conclusions.
Journalism
Tiny titanium dioxide particles in food raise blood sugar, disrupt gut hormones in mice, study finds, by Pamela Ferdinand, U.S. Right to Know, May 12, 2025
Why Is a Sunscreen Ingredient in My Frozen Pizza?, by Andrea Petersen, Wall Street Journal, June 10, 2024
Food additive nanoparticles could negatively affect your gut health, by Jillian McCarthy, Binghamton University, May 4, 2023
Food additive or carcinogen? The growing list of chemicals banned in EU but used in US, by Mikaela Conley, Guardian, June 23, 2022
Public health groups urge FDA to cancel titanium dioxide in food, by Center for Science in the Public Interest, May 30, 2023
Oman Bans Food Products Containing Titanium Dioxide, by Gulf News Report, July 23, 2023
Titanium Dioxide: E171 no longer considered safe when used as a food additive byEuropean Food Safety Authority, May 6, 2021
Health advocates urge US regulators to ban common food coloring additive, by Tom Perkins, Guardian, June 2, 2023
A Lawsuit Claims Skittles Are Unfit for Consumption. Experts Weigh in, by Rachel Rabkin Peachman, New York Times, July 26, 2022
The trouble with titanium dioxide, by Siloam Springs Regional Hospital, Herald Leader, October 4, 2023
Reprinted under Creative Commons agreement from U.S. Right To Know.
Mikaela Conley is a science journalist at U.S. Right to Know. She has worked as a senior editor and producer for Yahoo News and previously as a health reporter for ABCNews.com.
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