Which E-numbers should you actually avoid?

An E-number is not a warning. It means the additive has been assessed and authorised for use in the EU, and the number is simply its identifier — E330 is citric acid, which is in every lemon. A long ingredient list is a sign of processing, which is worth its own attention, but the presence of an E-number tells you nothing on its own.

What is worth knowing is where a regulator has drawn a line. Those cases are documented, dated and public, and there are far fewer of them than the lists suggest.

Banned: E171 titanium dioxide

This is the one unambiguous case. In 2021 EFSA concluded that titanium dioxide could no longer be considered safe as a food additive, because a concern over genotoxicity could not be ruled out and no acceptable daily intake could be set. The EU withdrew its authorisation for food in 2022. If you find E171 in food inside the EU, it should not be there. It remains permitted in cosmetics and medicines, which are assessed under separate rules.

Mandatory warning: the six Southampton colours

E102 tartrazine, E104 quinoline yellow, E110 sunset yellow FCF, E122 carmoisine, E124 ponceau 4R and E129 allura red AC are still authorised, but foods containing them must carry the words "may have an adverse effect on activity and attention in children". That warning follows the 2007 Southampton study and is written into Regulation 1333/2008. It is the clearest signal EU law gives a shopper about an additive, and it is the reason these six turn up on every avoid-list — with a real basis, for once.

Azo dyes as a class are also associated with pseudo-allergic reactions such as urticaria in a small number of people, particularly those intolerant of aspirin or NSAIDs.

Declarable allergen: E220–E228 sulphites

Sulphites are not restricted for the general population, but above 10 mg/kg they must be declared as one of the EU's 14 allergens — because they genuinely provoke reactions, most often asthma symptoms in sensitive people. If sulphites affect you, this is the one number range worth learning by heart.

Context-dependent: E249–E252 nitrites and nitrates

Nitrites do a real job: they block Clostridium botulinum in cured meat. They can also form nitrosamines, some of which are carcinogenic, and the WHO's cancer agency classifies processed meat itself as carcinogenic to humans. EFSA re-evaluated nitrites in 2017 and kept an acceptable daily intake, concluding that exposure from additive use stays within safe levels for most people. In practice the meat is the larger question, not the additive.

The ones that keep appearing on lists without cause

E330 citric acid is made by fermentation and occurs in the body's own energy cycle; EFSA judged no intake limit necessary. E300 ascorbic acid is vitamin C. E621 MSG has not reproduced its reputed symptoms in controlled double-blind trials. E951 aspartame carries a genuine, specific warning — people with PKU must avoid it — and an acceptable daily intake for everyone else that was re-confirmed by EFSA and unchanged by the 2023 IARC review.

Which is the honest summary: a handful of numbers carry a documented restriction, and for most people the rest of the ingredient list — how processed the food is, how much salt and sugar it carries — matters more than the codes.

The question worth asking instead

"Is this additive bad?" has no general answer, because the answer depends on who is asking. E220 is irrelevant to most people and important if you are asthmatic. E951 is a hard block with PKU and unremarkable without it. Milk-derived additives matter to one reader and not the next.

That is the whole idea behind Ingredo.app: scan a product and the same ingredient list is re-read against your own conditions and diet, so a flag means something for you rather than in the abstract.