Titanium Dioxide in Food: What the Science Shows About E171

Titanium dioxide is the whitest white material known. It scatters light more efficiently than almost anything else. A tiny amount makes coatings, paints, sunscreen, and food brilliantly, opaquely white.

That optical performance is why it’s in a lot of food. And it’s why regulators on two sides of the Atlantic have reached very different conclusions about what to do with it.

What It Does in Food

Titanium dioxide (TiO2) is a naturally occurring mineral. In food, it’s used as a white colorant (E171 in Europe, listed as “titanium dioxide” in the US).

Its effect is straightforward: it makes things white. Very white. Uniformly white.

Think of the hard candy shell on an M&M. That bright white base layer, onto which the colored dye is applied, is partly titanium dioxide. The pigment creates an opaque barrier that makes the color on top pop.

You find it in:

• Candy coatings and shells
• Chewing gum coatings
• White and pastel-colored frostings
• Powdered sugar coatings on baked goods
• Some white sauces and dressings
• Certain vitamins and supplement capsule coatings

FDA permits titanium dioxide at up to 1% by weight of the food. That’s higher than most other color additives and reflects how efficiently even small amounts achieve the desired visual effect.

Without TiO2 or an equivalent, achieving the same level of whiteness requires much larger amounts of alternatives with worse optical performance. This is why the food industry has used it widely for decades.

The Nanoparticle Problem

Standard toxicology works with bulk materials. You test a compound, find what dose causes effects in animals, build in a safety margin, and set an acceptable intake.

Nanoparticles break this framework.

A material at nanoscale (particles under 100 nanometers) behaves differently from the same material in bulk form. The surface area to volume ratio is vastly higher. Nanoparticles can interact with biological systems differently. They can cross cell membranes that bulk particles can’t. They can reach tissues and organs that bulk particles don’t.

Food-grade titanium dioxide contains a mixture of particle sizes. A significant fraction of those particles are in the nano range (under 100 nm). The proportion varies by manufacturer and processing method. Typically, 30-50% of food-grade TiO2 particles are nano-sized by count, though they represent a smaller fraction by weight.

This is the problem EFSA confronted in its 2021 re-evaluation. The existing safety data was gathered using conventional bulk-material toxicology methods, which weren’t designed to assess nano-specific risks.

EFSA’s 2021 Conclusion

EFSA’s 2021 opinion on E171 was straightforward in its language: “titanium dioxide can no longer be considered safe as a food additive.”

The primary concern was genotoxicity. In vitro studies (cells in lab culture) showed TiO2 nanoparticles could cause DNA strand breaks and chromosomal damage. Some animal studies showed intestinal inflammation and pre-cancerous changes in colon tissue.

The critical issue was uncertainty, not proven harm. EFSA concluded it could not rule out genotoxicity based on the available evidence. Once a genotoxic concern exists, EFSA’s methodology doesn’t permit establishing a safe daily intake. Without an ADI, authorization can’t be maintained.

France had already acted unilaterally, banning food containing E171 by decree in January 2020 based on earlier research raising similar concerns. The EU-wide ban followed in August 2022.

FDA’s Current Position

FDA still permits titanium dioxide in the US.

The agency’s position is that the available evidence, while showing some in vitro genotoxic signals, hasn’t established that these effects occur at the doses encountered through normal food consumption. FDA points to the generally low gut absorption of TiO2 particles. Most TiO2 passes through the digestive tract without being absorbed. The fraction that’s absorbed is small.

FDA acknowledges the nano-specific concerns but hasn’t concluded they’re sufficient to restrict the additive at current use levels. An ongoing review is watching the literature.

This isn’t the same as saying TiO2 is safe. It’s saying the evidence isn’t yet strong enough for FDA to act.

What Industry Has Done

Several major food companies reformulated their products after the EU ban, especially those selling in both US and European markets. When a reformulation is needed for Europe, many companies apply it globally rather than maintain two versions.

Mars reformulated its European candy products. Some chewing gum companies changed their coatings. Supplement manufacturers found alternatives for capsule coatings.

The alternatives, primarily calcium carbonate, modified starch, and certain plant-derived pigments, are less optically efficient. They don’t produce the same perfect whiteness that TiO2 achieves. But they work well enough for most applications, which is why reformulation has been achievable.

The Gap in Nanotoxicology

EFSA’s concern is as much about what we don’t know as about what we do.

Conventional food safety testing wasn’t built for nanomaterials. The tests don’t distinguish between nano and bulk particle effects. They don’t characterize particle size distribution. They measure overall toxicity endpoints but miss nano-specific mechanisms.

This is a gap in the science, not just in regulatory methodology. The research community has been working to develop better nanoparticle-specific safety testing frameworks, but that work isn’t complete.

In the meantime, regulators face a choice: wait for better methods and keep the substance in use, or apply the precautionary principle and restrict it while better methods develop. EFSA chose the latter. FDA has not.

The Verdict

Caution reflects a genuine regulatory disagreement based on real scientific uncertainty about nanotoxicology.

The EU ban isn’t based on proven harm. It’s based on the inability to rule out harm using current testing methods. That’s a meaningful distinction, and reasonable people can disagree about how to act on that level of uncertainty.

What’s clear: titanium dioxide in food serves a purely cosmetic function (whiteness). The concern involves a serious potential endpoint (DNA damage). Several major markets have moved to ban it. And the alternatives work.

That combination makes reducing exposure a reasonable preference. Choosing products without titanium dioxide costs nothing and avoids an open question.