Top E Numbers to Avoid

If you've ever turned a packet over and spotted something like "E621" or "E133" in the ingredients, you've probably wondered what these codes mean, whether they're all harmful, and which ones are genuinely worth steering clear of. The short answer is that most are fine, some are useful, and a handful are worth a closer look.

Understanding E numbers

An E number is a code given to a food additive that has been assessed for safety and approved for use. The "E" originally stood for Europe. After Brexit, the UK generally aligns with EU standards on E numbers, with enforcement and any local variations overseen by the Food Standards Agency in England and Wales, Food Standards Scotland north of the border, and EU rules still applying in Northern Ireland under the Windsor Framework. In practice, the same numbering system is used across the UK and the EU, which keeps things simple for shoppers.

The numbers cover a wide range of ingredients, including colours, preservatives, antioxidants, sweeteners, emulsifiers, gelling agents and flavour enhancers. The code only tells you that an additive has been tested and given an identifier, not that it's harmful. Plenty of ordinary substances have E numbers attached to them. Vitamin C is E300, paprika extract is E160c, and even oxygen has one (E948). Many preservatives have done a great deal of good by reducing the risk of serious food poisoning, including botulism.

That said, some additives have been associated with side effects in certain people, often because of sensitivity, allergy, or an existing condition that the ingredient can make worse. It's reasonable to take an interest in what's in your food, particularly if you're shopping for children or anyone with a known intolerance.

The "Southampton Six" colours

Six artificial colours have been associated with hyperactivity and reduced attention in some children, based on research originally carried out at the University of Southampton. They are:

• E102 tartrazine
• E104 quinoline yellow
• E110 sunset yellow FCF
• E122 carmoisine
• E124 ponceau 4R
• E129 allura red

These colours are still legally permitted, but the FSA encouraged UK manufacturers to phase them out voluntarily, and most major brands have done so. Where they are used, the label must carry a warning along the lines of: "may have an adverse effect on activity and attention in children." This wording comes from EU regulations that the UK still follows in practice. If you spot a product, especially one aimed at children, that contains these colours without the warning, you can report it to the FSA or to your local authority's trading standards team.

Other E numbers some people prefer to avoid

The list below isn't a blanket warning. These are additives that have attracted concern or that some people choose to cut out, often because of sensitivities.

E621 monosodium glutamate (flavour enhancer)

Better known as MSG, this is a flavour enhancer used to boost the savoury taste of all sorts of products, from crisps and stock cubes to ready meals. Most people tolerate it without issue, but a minority report headaches, nausea, flushing or palpitations after eating it. If you've noticed a pattern after certain meals, it's worth checking labels.

E951 aspartame (artificial sweetener)

Aspartame is used widely in low sugar drinks, diet foods, desserts and chewing gum. In 2023, the World Health Organization's cancer research agency classified it as "possibly carcinogenic to humans", though the joint expert committee on food additives kept the existing acceptable daily intake. UK regulators continue to consider it safe at normal levels of consumption. Anyone with phenylketonuria (PKU) must avoid it, which is why products containing it carry a warning about phenylalanine.

E211 sodium benzoate (preservative)

Used as a preservative in soft drinks, salad dressings, pickles, sauces and some margarines. It has been associated with hyperactivity in children when combined with certain artificial colours, and it can trigger reactions in people with asthma or existing allergies. There's also some concern about the way it reacts with vitamin C (E300) to form small amounts of benzene, although manufacturers have largely reformulated drinks to prevent this.

E213 calcium benzoate (preservative)

A close relative of sodium benzoate, used for the same job of extending shelf life. It crops up in low sugar products and can provoke reactions in people prone to allergies or asthma.

E151 brilliant black BN (colour)

A synthetic black dye used in a small number of products such as sauces, blackcurrant drinks and certain desserts. Some people report allergic reactions to it, and it is banned or restricted in several countries, including Canada and the United States.

E133 brilliant blue FCF (colour)

Another synthetic colouring, used to produce vivid blue or green shades. Some people report allergic reactions, particularly those who already have asthma or aspirin sensitivity. It's permitted in the UK and across most of Europe, but some countries have restricted it.

Your situation may be slightly different. ask a question below ↓ and our editorial team will reply with our advice.

How to keep an eye on additives

UK food labelling rules require additives to be listed by either their full name or their E number, along with their function (for example, "preservative" or "colour"). If you want to limit certain ingredients, the ingredients list is the place to look. Products labelled as organic tend to use far fewer additives, because organic certification restricts which ones are allowed.

If you suspect a particular additive is affecting you or a family member, keep a simple food diary and speak to your GP or a registered dietitian. Reactions can sometimes be down to other ingredients entirely, so professional advice is more reliable than guesswork.

Want the full list?

For a full breakdown of what each code means and what it does, see our complete overview of E numbers. Each entry links through to more detail if you want to read further.

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