also: Aluminium colour · metallic aluminium · CI 77000 · pigment metal
Metallic aluminium powder used as a silver decorative coating on sugar confectionery and cake decorations. Its EU food authorisation expired in February 2014 and no food category in the current consolidated Regulation 1333/2008 lists E173 as permitted.
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Gorgonzola Cheese (Milk) (50%) · Full Fat Mascarpone Cheese (Mascarpone Cheese (Milk) · Acidity Regulator: Citric Acid). Aluminium strip not edible. Some flecks of it may be present. Remove it carefully before eating.
Aluminium accumulates in bone and, at sustained high intake, can impair bone mineralisation.
Why it’s worth knowing. Aluminium accumulates in bone and, at sustained high intake, can impair bone mineralisation. Animal studies show neurodevelopmental and reproductive harm. EFSA found the tolerable weekly intake is likely exceeded in a significant proportion of the European population, particularly in children, from food sources overall.
Aluminium (chemical symbol Al) is the most abundant metallic element in the Earth's crust. As a food additive it is used in very fine powder form, giving a metallic silver-grey appearance. Commercially it is produced by electrolysis of aluminium oxide derived from bauxite ore.
Acts as a surface colourant only. Fine aluminium particles adhere to the outer coating of sugar confectionery, creating a bright metallic sheen. It is applied externally and is not incorporated into the food itself. Unlike soluble food dyes it does not migrate into the surrounding food matrix.
Historically found on the surface of silver dragees (the hard ball-cake decorations), sugar-coated confectionery, and decorative elements on celebration cakes and pastries. Its EU authorisation for these uses expired on 1 February 2014. On a UK label it would appear as 'E173' or 'aluminium' in the ingredients list.
The critical endpoint used by EFSA and SCHEER to set the tolerable intake for aluminium is neurodevelopmental toxicity observed in animal studies. A key 12-month rat study by Poirier et al. (2011) found adverse neurodevelopmental effects at doses from 100mg/kg body weight per day, establishing a no-observed-adverse-effect level (NOAEL) at 30mg/kg/day. SCHEER used this NOAEL plus a safety factor of 100 to set a tolerable daily intake. EFSA separately derived a tolerable weekly intake in 2008 using a weight-of-evidence approach across neurotoxicity, developmental toxicity, and other studies.
EFSA established a tolerable weekly intake (TWI) of 1mg aluminium per kg body weight per week in 2008, based primarily on neurotoxicity and developmental neurotoxicity data from animal studies. This was a seven-fold reduction from the previous JECFA provisional TWI of 7mg/kg/week.
SCHEER (EU Scientific Committee on Health, Environmental and Emerging Risks) identified neurodevelopmental effects in a GLP-compliant rat study (Poirier et al. 2011) as the critical endpoint, deriving a tolerable daily intake of 0.3mg/kg body weight per day using that study's NOAEL.
EFSA's 2008 assessment found that the tolerable weekly intake it had just set was likely already being exceeded in a significant part of the European population, particularly children. Average estimated dietary exposure in children ranged from 0.7 to 2.3mg aluminium per kg body weight per week, which can exceed the 1mg/kg TWI at the upper end. Adult exposure was estimated at 0.2 to 1.5mg/kg/week. Main dietary sources are cereals and cereal products, vegetables, and beverages rather than food additives. Some soya-based infant formulae showed aluminium concentrations up to four times higher than average.
Children's estimated dietary aluminium exposure ranged from 0.7 to 2.3mg/kg body weight per week, with high consumers potentially exceeding the 1mg/kg TWI. Adults ranged from 0.2 to 1.5mg/kg/week.
EFSA noted that some highly exposed consumers may exceed the TWI by up to two-fold, and recommended reviewing conditions of use for aluminium-containing food additives to reduce population exposure.
Absorbed aluminium accumulates primarily in bone tissue. In patients with impaired kidney function (who cannot excrete aluminium efficiently), aluminium deposits at the bone-osteoid interface and inhibits normal mineralisation, producing a painful condition called aluminium-induced osteomalacia. This bone toxicity is established at high systemic doses seen in dialysis patients but has not been demonstrated from ordinary dietary exposure in people with normal kidney function. EFSA nonetheless identified bone effects as one of the endpoints informing the TWI.
In people with chronic renal failure and in dialysis patients exposed to high aluminium loads, aluminium accumulates at the bone-osteoid interface and inhibits mineralisation, leading to osteomalacia and adynamic bone disease.
Aluminium's primary accumulation site in the body is bone; absorbed dietary aluminium is sequestered there for long periods, and EFSA included bone effects in the weight-of-evidence basis for the TWI.
Multiple animal studies show that high doses of aluminium compounds can disrupt reproductive function in male rodents, including reduced sperm counts, lower testicular weights, and altered hormone levels. Two-generation studies have shown decreased pregnancy rates when males were exposed at 100mg/kg/day or above. These effects were found at doses far higher than typical dietary exposure, and EFSA did not establish a specific reproductive toxicity endpoint for its TWI, but considered the data as part of its overall weight of evidence.
High-dose aluminium exposure in male mice produced significantly decreased testicular and epididymal weights, reduced sperm and spermatid counts, and decreased pregnancy rates in mated females.
A review of aluminium reproductive toxicity found consistent evidence across animal studies of adverse effects on spermatogenesis and steroidogenesis at high doses, including through oxidative stress and disruption of the blood-testis barrier, but concluded human evidence at dietary levels is insufficient to determine risk.
Laboratory studies show aluminium damages neural tissue through oxidative stress, mitochondrial dysfunction, and neuroinflammation. The link to Alzheimer's disease has been debated for decades. EFSA's 2008 opinion and subsequent reviews by JECFA and the European SCCS concluded that dietary aluminium exposure has not been shown to cause Alzheimer's disease in humans, though the question has not been fully closed. A 2025 systematic review and meta-analysis found associations between environmental aluminium exposure and Alzheimer's risk in some studies, but the overall evidence remains inconclusive.
EFSA concluded in 2008 that it did not consider exposure to aluminium via food to constitute a risk for developing Alzheimer's disease, based on the available evidence at that time.
Laboratory and animal research identifies aluminium-induced oxidative stress, mitochondrial dysfunction, and neuroinflammation as mechanisms capable of damaging neural tissue, though whether these translate to harm at dietary exposure levels in healthy humans remains debated.
A 2025 systematic review and meta-analysis found observational associations between environmental aluminium exposure and Alzheimer's disease risk but noted significant heterogeneity and methodological limitations across included studies.
Commission Regulation (EU) No 380/2012 amended Annex II to Regulation (EC) No 1333/2008 specifically to reduce aluminium intake from food additives in response to EFSA's 2008 finding that the TWI was being exceeded. For E173, the regulation permitted it only as external coating of sugar confectionery for cake decoration, and only until 1 February 2014. After that date, no food category in the consolidated EU regulation lists E173 as a permitted colour. The UK FSA's own guidance on its register explicitly acknowledges that 'the period of application for some food additives have expired but they have not been removed from the domestic list' -- citing aluminium silicate (E559) and calcium aluminium silicate (E556), which had the same 31 January 2014 sunset, as named examples. The 'Authorised' label in the UK data register therefore reflects the additive's presence in the colours list, not any currently active food use permission.
Commission Regulation (EU) No 380/2012 set a sunset date of 1 February 2014 for E173 aluminium as an external coating for sugar confectionery. The stated reason was to reduce population aluminium exposure in light of EFSA's 2008 finding that the TWI was being exceeded.
The UK FSA's register guidance states: 'The period of application for some food additives have expired but they have not been removed from the domestic list e.g. the authorisations for calcium aluminium silicate (E 556) and aluminium silicate (Kaolin) (E 559) ended on 31 January 2014.' This confirms the register's 'Authorised' status for E173 does not indicate active food use permission.
The UK FSA approved additives list includes E173 in its colours section and the UK data.food.gov.uk register records it as 'Authorised' as of 31 December 2020; however, the detailed conditions of use in Annex II of assimilated Regulation 1333/2008 contain no current food category permitting E173.
People with kidney disease or impaired renal function are at heightened risk from aluminium accumulation, as the kidneys are the main excretion route. Infants and children are a higher-risk group because their exposure relative to body weight is greater and their developing nervous systems may be more vulnerable. On a label, look for 'E173' or 'aluminium' in the ingredients list; in practice, given the expired EU food authorisation, encountering it in food is now rare.
E173 sits in an unusual regulatory position: the UK FSA still lists it as a colour in its approved additives table, but the only food use that was ever authorised for it in UK and EU law expired in February 2014. The FSA's own register guidance confirms this is a known pattern: additives with expired permissions remain listed but are no longer actively permitted. Since 2014, no food manufacturer in the UK or EU should legitimately be using it. The broader aluminium story is active: EFSA found in 2008 that a significant part of the population, especially children, was already exceeding the tolerable weekly intake from all food sources, mainly cereals and vegetables rather than food additives. Whether aluminium at dietary levels causes long-term harm to the nervous system in healthy adults remains genuinely unsettled. The bone and reproductive effects established in animal studies appear at doses far above typical dietary exposure. The Alzheimer's question has not been resolved, despite EFSA's 2008 conclusion that food exposure is not a demonstrated risk for the disease.
The UK FSA lists E173 in its approved food colours table and its register shows it as 'Authorised'. However, the FSA's own guidance on the register explicitly states that additives whose periods of application have expired are not removed from the domestic list. The only food use ever authorised for E173 (as an external coating on sugar confectionery for cake decoration) expired on 1 February 2014 under EU Regulation 380/2012, and no new authorisation has been issued. No food category in current UK food law actively permits its use.
In 2008, EFSA reviewed the safety of dietary aluminium and found that a significant proportion of the European population, particularly children, was likely already exceeding the tolerable weekly intake of 1mg/kg body weight per week from food overall, primarily from cereals, vegetables and beverages rather than food additives. The European Commission responded in 2012 by restricting or removing the authorisation for several aluminium-containing food additives, including setting a sunset date of 1 February 2014 for E173.
Before the 2014 sunset, E173 was used as a metallic silver coating on dragees (the hard sugar-coated ball decorations used on cakes), sugar-coated confectionery, and decorative cake and pastry elements. Given the expired EU food authorisation, food products sold in the UK or EU should not contain E173. It may still appear on products manufactured in countries where it remains permitted.
Yes. E173 is metallic aluminium, a mineral derived from bauxite ore through an industrial electrolysis process. It contains no animal-derived ingredients.
Last reviewed: 20 June 2026
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