E-numbers / Other additives / E918
also: Nitrogen oxide · Oxides of nitrogen · NOx
A group of reactive nitrogen gases (mainly nitric oxide and nitrogen dioxide) used historically as flour treatment agents. Not currently a permitted food additive in the UK.
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E918 is not authorised for use in UK or EU food.
Why it’s worth knowing. E918 is not authorised for use in UK or EU food. Nitrogen dioxide is a recognised respiratory irritant and lung toxicant at elevated concentrations. If it appears on a label, the product may not comply with UK food additive law.
E918 refers to nitrogen oxides, a collective term for reactive nitrogen-oxygen gas mixtures, principally nitric oxide (NO) and nitrogen dioxide (NO2). These are distinct from nitrous oxide (E942, N2O) and from inert nitrogen gas (E941, N2). Nitrogen dioxide is a reddish-brown gas with a sharp, pungent odour and is a well-known component of atmospheric air pollution. Nitric oxide is a colourless gas with important biological roles at trace levels in the body.
Historically, nitrogen oxide gases were investigated and used as flour treatment agents: the oxidising action of NO2 on gluten proteins can mature and bleach wheat flour, improving dough handling and bread volume. The gas reacts with thiol groups on gluten proteins, stiffening the gluten network. It also has some bleaching effect on flour carotenoids, producing a whiter crumb.
E918 has no currently authorised food use in the UK or EU. Historically, nitrogen dioxide gas was applied during the milling process as a flour improver in some countries. It is not a consumer-level ingredient found in packaged retail foods. If listed on a UK product label as E918 or 'nitrogen oxides', that product falls outside current permitted additive law.
Nitrogen dioxide is classified as a respiratory irritant and lung toxicant by health and occupational safety authorities worldwide. At ambient air-pollution concentrations it is associated with aggravated asthma and reduced lung function, particularly in children and people with pre-existing respiratory conditions. At occupational or high-concentration exposures it can cause pulmonary oedema. The relevance to food additive use at permitted levels would be low, but the absence of authorisation in the UK and EU means those permitted levels do not currently exist.
Nitrogen dioxide at air-pollution concentrations is associated with increased respiratory symptoms, reduced lung function, and aggravated asthma, especially in children.
NO2 is classified as a respiratory irritant; high-concentration occupational exposure causes pulmonary oedema and can be fatal.
E918 does not appear in the UK Food Standards Agency's current list of approved food additives, which implements the retained EU Regulation 1333/2008 (Annex II) in Great Britain. Any former use as a flour treatment agent has not been carried into the post-Brexit GB approved list. The European Food Safety Authority has not published a current re-evaluation opinion approving E918 under the 1333/2008 framework.
E918 is not listed among the permitted food additives in the UK FSA's approved additives and E numbers register.
E918 has no authorised food use in the UK, so no UK consumer should encounter it in a lawfully produced product. Anyone with asthma or respiratory conditions would be particularly vulnerable to nitrogen oxide gases. Look for 'E918' or 'nitrogen oxides' on ingredient lists as a signal of a non-compliant product.
E918 sits at an unusual intersection: it carries an E-number designation within the international numbering system, but it is not authorised for food use in the UK or EU. The underlying chemistry, nitrogen oxides including NO2, is the same chemistry involved in air pollution. The science on nitrogen oxide respiratory hazard is well-established from environmental and occupational research, but direct evidence of harm from historical low-level food additive use is limited, largely because authorisation was not pursued. The absence from the approved list is itself the key fact here: this is not a question of disputed safety at permitted levels, but of a substance that has no permitted level in UK or EU food law.
E918 is not listed as an approved food additive in the UK. It does not appear on the UK FSA's approved additives and E numbers register, meaning it has no authorised food use in Great Britain. Whether it was formally banned or simply never authorised under the current regulatory framework, the practical effect is the same: it cannot lawfully be added to food sold in the UK.
E-numbers are an international numbering system for food additives, administered by the Codex Alimentarius Commission and the EU. Having an E-number means a substance was evaluated and assigned a reference number, not that it is currently approved for use. Some substances were evaluated and either not authorised or had former authorisation that was not carried forward when the EU consolidated its food additive list under Regulation 1333/2008.
No UK or EU food products should lawfully contain E918, as it is not a permitted food additive. Historically, nitrogen dioxide gas was used in flour treatment in some countries, but this use is not authorised in the UK or EU under current law.
Nitrogen oxides are inorganic gases, not derived from animals or animal by-products. The vegan status of E918 as a substance is not in question, but since it is not an authorised food additive in the UK or EU, the question of its presence in vegan food products does not arise under current law.
Last reviewed: 20 June 2026
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