Propane-1,2-diol
A synthetic solvent and humectant that keeps food moist and carries flavourings. Not an authorised UK or EU food additive E-number; the same substance is permitted as E1520.
What is it?
Propane-1,2-diol, also known as propylene glycol, is a clear, odourless, slightly sweet synthetic liquid made from propylene oxide. It is chemically a diol (two hydroxyl groups on a three-carbon chain). In food use it acts as a solvent, humectant (moisture-retaining agent) and carrier for flavourings and colourings.
What does it do?
Its two hydroxyl groups allow it to bind water molecules, preventing food from drying out (humectant effect). As a solvent it dissolves flavourings, colourings and other additives that would otherwise not disperse evenly in a food matrix. It also lowers water activity slightly, which slows microbial growth.
Where you will see it
It is used in flavouring preparations, soft-drink concentrates, confectionery glazes, baked goods, chewing gum, dessert mixes and some processed sauces. In the UK and EU its permitted food use is covered under the E-number E1520, not E490. On a UK label it appears as 'propylene glycol', 'propane-1,2-diol', or 'E1520'.
What the science says
Established ADI and exposure assessment
EFSA's food additive panel re-evaluated propane-1,2-diol in 2018 and retained an acceptable daily intake (ADI) of 25 mg per kg of body weight per day. At reported use levels in food, mean and high (95th percentile) dietary exposure in all population groups remained within that ADI. The panel found no new toxicological data requiring the ADI to be lowered.
EFSA ANS Panel concluded that dietary exposure to propane-1,2-diol from its use as a food additive (E1520) did not exceed the ADI of 25 mg/kg bw/day in any population group at reported use levels.
Beverage exposure in context
A 2025 tiered intake assessment for propylene glycol in beverages found that in realistic consumption scenarios, dietary intake from beverages alone approached the ADI only for high-consuming children in worst-case scenarios, not at typical adult intakes. The authors noted that flavouring uses (Annex III of EU Regulation 1333/2008) are the dominant route of exposure and that cumulative exposure from all food categories warrants monitoring.
Tiered intake modelling for propylene glycol in beverages found that only high-end child consumers in brand-loyal worst-case scenarios approached the ADI, not typical adult consumers.
E490 vs E1520: the E-number situation
The designation 'E490' for propane-1,2-diol does not appear in the UK FSA approved additives list or in EU Regulation 1333/2008. The authorised food additive E-number for the same substance is E1520. The E490 designation circulates in cosmetics, pharmacy and some food-labelling databases but is not a valid UK or EU food-use E-number. Related substances propane-1,2-diol alginate (E405) and propane-1,2-diol esters of fatty acids (E477) carry their own authorisations and have been separately re-evaluated by EFSA.
The UK FSA regulated-products database lists propane-1,2-diol under E1520 as authorised in England, Scotland and Wales; no entry exists for E490 as a food additive.
Where it stands with the regulators
Who should be careful
People on a strict vegan diet should note that propylene glycol can be derived from petroleum-based propylene oxide (technically vegan) but may also function as a carrier for non-vegan colourings or flavourings. Look for 'propylene glycol', 'propane-1,2-diol', or 'E1520' on the label. There is no allergen declaration requirement for this substance under UK food law.
The honest read
Propane-1,2-diol is a well-characterised industrial chemical with decades of food, pharmaceutical and cosmetic use. The science on its safety at typical food-additive doses is substantially settled at the population level, with EFSA's 2018 review finding no new concern requiring tightening of the ADI. The one genuine monitoring question, noted in recent intake modelling, is cumulative exposure in high-consuming children from all food categories combined, because it is used both as a direct food additive and as a carrier for flavourings, meaning it can appear in a product twice without being obviously visible. At present, no regulator has flagged that as a safety breach, but it is an active area of dietary exposure monitoring rather than a closed file.
Related additives
Common questions
Is E490 banned in the UK?
E490 is not an authorised food additive E-number in the UK or EU, so it has no food-law status to be banned or permitted. The same substance, propane-1,2-diol, is lawfully used in food under the E-number E1520. If you see 'E490' on a UK food label it is technically a labelling inaccuracy; the correct designation is E1520.
Is propylene glycol the same as antifreeze?
Propylene glycol is used in some food-grade and industrial antifreeze products because it lowers the freezing point of water, but propylene glycol itself is a different compound from ethylene glycol, the more toxic antifreeze chemical. The two are not interchangeable.
What foods contain propane-1,2-diol (E1520)?
It is used in flavouring preparations, soft-drink concentrates, chewing gum, confectionery glazes, some baked goods, dessert mixes and processed sauces. Because it also serves as a carrier for flavourings and colourings, it may appear in many products without being immediately obvious. On the label look for 'propylene glycol', 'propane-1,2-diol', or 'E1520'.
Is E490 / propylene glycol vegan?
Propylene glycol itself is synthesised from petroleum-based propylene oxide and contains no animal-derived ingredients. However, it is commonly used as a carrier for flavourings or colourings that may be derived from animal sources, so whether a specific product is vegan depends on what the propylene glycol is carrying, not the propylene glycol alone.
Sources
- EFSA ANS Panel, Re-evaluation of propane-1,2-diol (E 1520) as a food additive, EFSA Journal 2018
- PubMed record: Re-evaluation of propane-1,2-diol (E 1520) as a food additive
- UK FSA regulated-products database: E1520 (propane-1,2-diol)
- UK Food Standards Agency: Approved additives and E numbers
- Taylor and Francis, Food Additives and Contaminants: Tiered intake assessment for propylene glycol in beverages, 2025
- EFSA ANS Panel, Re-evaluation of propane-1,2-diol esters of fatty acids (E 477) as a food additive, EFSA Journal 2018
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