Most Controversial Food Additives

Food additive controversies typically arise from one or more of the following situations: (1) animal studies showing adverse effects at high doses, even if human dietary exposure is far lower; (2) epidemiological associations that may or may not be causal; (3) mechanistic concerns (e.g., genotoxicity potential) even without direct evidence of harm in humans; (4) divergent decisions by different regulatory bodies based on the same or similar evidence; or (5) public perception shaped by media coverage that may not accurately represent scientific consensus.

This guide examines the most frequently debated additives, presenting what major regulatory agencies — EFSA (European Food Safety Authority), FDA (U.S. Food and Drug Administration), and JECFA (Joint FAO/WHO Expert Committee on Food Additives) — have actually concluded based on the scientific evidence. This guide does not offer personal safety advice or health recommendations.

Titanium dioxide (E171) was used as a white colorant in candies, chewing gum, and some sauces. In May 2021, EFSA concluded that titanium dioxide can no longer be considered safe as a food additive, primarily because it could not rule out genotoxicity — the ability to damage DNA. The concern was not based on direct evidence of harm in humans, but on the precautionary principle: because genotoxicity could not be excluded, a safe ADI could not be established. The EU banned E171 in food from August 2022.

In contrast, the FDA continues to list titanium dioxide as a permitted color additive (21 CFR 73.575), noting that existing evidence has not demonstrated harm at levels used in food. Australia/NZ and Japan also maintain approval. The divergence highlights the different risk thresholds applied by different regulatory systems.

Full E171 regulatory profile with country-by-country status →

Sodium nitrite (E250), potassium nitrite (E249), sodium nitrate (E251), and potassium nitrate (E252) are used as preservatives and color fixatives in cured meats such as bacon, ham, and sausages. They prevent the growth of Clostridium botulinum (botulism), and are responsible for the characteristic pink color of cured meats.

The controversy centers on the formation of nitrosamines — compounds that can form when nitrites react with amines in protein-rich foods during high-temperature cooking (e.g., frying bacon). Some nitrosamines are classified as probable human carcinogens (IARC Group 2A). EFSA conducted a comprehensive evaluation in 2017 and 2023, acknowledging that dietary exposure to nitrites and the resulting nitrosamines is of concern, and recommending reduced intake of processed meats.

Regulatory agencies have not banned these additives but have progressively reduced maximum permitted levels. Their continued approval reflects a risk-benefit assessment: the benefit of preventing botulism and other foodborne diseases is weighed against the risk from nitrosamine formation. Naturally occurring nitrates from vegetables like spinach, lettuce, and beets are typically consumed in higher quantities than nitrates from food additives.

See individual profiles: E249, E250, E251, E252

Aspartame is the most studied artificial sweetener in history, with thousands of peer-reviewed studies in the scientific literature. In July 2023, IARC classified aspartame as "possibly carcinogenic to humans" (Group 2B), triggering significant media coverage. On the same day, JECFA concluded that the existing ADI of 0–40 mg/kg bw/day remains appropriate and does not need revision. EFSA stated it had no reason to revise its 2013 safety assessment.

The IARC Group 2B classification reflects "limited evidence" of carcinogenicity, primarily from observational studies showing associations between sweetened beverage consumption and hepatocellular carcinoma. Such observational data cannot establish causation and are subject to confounding variables. The JECFA and EFSA positions represent the risk assessment perspective — whether the actual levels consumed in food present a meaningful health risk.

Full aspartame regulatory profile → | Sweeteners comparison guide →

Butylated hydroxyanisole (BHA, E320) and butylated hydroxytoluene (BHT, E321) are synthetic antioxidants used to prevent oils and fats from going rancid. They are found in cereals, chewing gum, snack foods, and packaging materials.

BHA is listed by IARC as Group 2B (possibly carcinogenic) based on evidence in animal studies of carcinogenicity in the forestomach of rats and hamsters — an organ that humans do not have. This has led some consumer groups to raise concerns, while regulatory agencies maintain that the animal data are not directly applicable to human risk assessment. EFSA re-evaluated both BHA and BHT and established ADI values, concluding they are safe at permitted use levels. The FDA considers both substances GRAS. Japan has restricted certain uses of BHA.

E320 BHA profile → · E321 BHT profile →

MSG (monosodium glutamate, E621) is one of the most misunderstood food additives. Glutamate — the primary component — is one of the most abundant amino acids in nature and is naturally present in high quantities in tomatoes, parmesan cheese, soy sauce, mushrooms, and many other foods. MSG simply adds the sodium salt form to food to enhance umami flavor.

EFSA evaluated MSG in 2017 and established an ADI of 30 mg/kg bw/day for added glutamates (all forms combined), noting that habitual consumers could exceed this in the EU population. However, EFSA did not ban or restrict MSG — it simply recommended monitoring of exposure levels and potential review of maximum use levels in some food categories.

The "Chinese restaurant syndrome" concept has not been validated by controlled scientific studies. JECFA considers MSG acceptable for use without a specified ADI at typical food use levels (meaning it is safe to use at the level needed for technological effect).

Full MSG regulatory profile →

Potassium bromate (E924) is a flour treatment agent used to strengthen bread dough and improve baking performance. IARC classifies it as Group 2B (possibly carcinogenic). It has been banned as a food additive in the EU, Japan, Canada, Australia/NZ, and many other countries. However, it remains permitted for use as a flour treatment agent in some countries, including certain states in the USA, where it is listed as an approved indirect food additive under specific conditions.

The concern is that if used improperly (wrong amount, insufficient baking time/temperature), residual bromate may remain in the final baked product. When used correctly, bromate is converted to bromide during baking and residual levels are minimal. The FDA recommends that bakers not use potassium bromate, though it has not formally banned it. As of 2024, California passed legislation banning several additives including potassium bromate in food products sold in the state.

Full E924 regulatory profile →

Azodicarbonamide (ADA, E927a) is a flour bleaching and improving agent that attracted significant public attention in the USA when it was identified as an ingredient in certain fast food breads. It is banned as a food additive in the EU, Japan, Australia/NZ, and many other countries. The EU and other jurisdictions prohibited it based on concerns about semicarbazide — a decomposition product of ADA during baking — which showed carcinogenic effects in mouse studies.

The FDA approves azodicarbonamide as a dough conditioner at a maximum level of 45 ppm under 21 CFR 137.105. The FDA has noted that the semicarbazide levels found in bread are substantially below levels that caused tumors in mice, and that the relevance of the mouse data to human health is uncertain. The World Health Organization has recommended that its use as a flour treatment agent should be discontinued.

Full E927a regulatory profile →

Six artificial food colors — tartrazine (E102), quinoline yellow (E104), sunset yellow (E110), carmoisine (E122), ponceau 4R (E124), and allura red (E129) — became known as the "Southampton Six" after a 2007 study published in The Lancet found a statistically significant association between mixtures of these colors (combined with sodium benzoate) and increased hyperactivity in children.

EFSA evaluated the Southampton study in 2008 and concluded that the evidence was not sufficient to change the safety assessment of these colors individually, partly because the study tested a mixture (not individual colors) and partly due to methodological limitations. However, EFSA acknowledged the statistical association and recommended further research. As a precautionary measure, the EU introduced mandatory warning labels for products containing these colors: "may have an adverse effect on activity and attention in children."

The UK's Food Standards Agency recommended voluntary phase-out by manufacturers, which several companies adopted. In the USA, the FDA reviewed the same evidence and concluded it did not support a causal link between these colors and hyperactivity at typical intake levels, and did not require warning labels or phase-outs.

Individual profiles: E102 · E110 · E122 · E124 · E129

Parent's guide to additives and children →