What is E173?

Complete guide to understanding E173 (Aluminium Powder) – the metallic food colorant with health controversy

The Quick Answer

E173 is aluminium powder—a metallic food colorant that imparts a silver-grey appearance to foods. It’s a natural metal that is mined and processed into fine powder form for use in food decoration. E173 is used exclusively for surface coating of foods—providing a metallic, shimmering appearance to confectionery, cakes, dragées, and other decorative food items.

E173 is the only form of metallic aluminium approved for food use in the EU. It is approved for “quantum satis” (as much as needed) use limited to surface coating applications only. However, E173 is highly controversial due to accumulating evidence of potential health risks associated with aluminium exposure, including possible neurotoxicity, effects on bone health, and potential links to neurodegenerative diseases like Alzheimer’s disease.

E173 is EU-approved but with significant health controversy. The FDA does not approve aluminium as a direct food additive in the United States. Actual dietary exposure from E173 surface coating is minimal compared to total aluminium intake from other sources (water, soil, packaging, cookware), but the cumulative effect of multiple aluminium exposure sources is increasingly recognized as a health concern.

What Exactly Is It?

E173 is aluminium metal (Al) in powdered form—the 13th element on the periodic table, mined from bauxite ore and processed into fine particles for use as a food colorant. Aluminium is the most abundant metal in Earth’s crust, making up about 8% of the crust by weight. It naturally occurs in rocks, soils, water, and air.

Think of E173 as finely ground metallic silver. When applied to food surfaces, the metallic particles reflect light, creating a shimmering, metallic appearance. The powder itself is insoluble in water—it doesn’t dissolve into the food but rather sits on the surface, providing visual appeal without changing flavor.

Key characteristic: E173 is a pure element—not a compound. This distinguishes it from most other food colorants which are chemical compounds. However, this elemental nature also underlies health concerns: the body has limited ability to eliminate accumulated metals, leading to potential bioaccumulation.

Chemical identity:

• Element: Aluminium (Al); atomic number 13
• Atomic weight: 26.98 g/mol
• Crystal structure: Face-centered cubic (FCC) metallic structure
• Naturally occurring: Element; third most abundant element in Earth’s crust
• Reactivity: Rapidly oxidizes when exposed to air forming aluminum oxide (Al₂O₃) surface layer protecting underlying metal
• Density: 2.70 g/cm³ (lightweight metal)

How it’s sourced/made:

E173 is produced from natural ore:

• Primary source: Bauxite ore; mined from deposits worldwide
• Extraction process: Bauxite processed through Bayer process to obtain aluminum oxide (alumina)
• Smelting: Alumina reduced through electrolysis (Hall-Héroult process) to obtain pure aluminum metal
• Powder production: Aluminum metal atomized or ground into fine powder for food-grade specifications
• Purity: Processed to remove impurities; food-grade specification typically >99% aluminum
• Natural metal: E173 is a naturally occurring element; not synthetically manufactured but extracted and processed

Where You’ll Find It

E173 appears in foods exclusively for surface decoration/coating:

Primary Food Applications:

• Confectionery and dragées (PRIMARY USE) – sugar-coated almonds, chocolates, decorative candies; silver/metallic coating
• Cake decorations (PRIMARY USE) – icing decorations, cake toppings, edible metallic elements
• Specialty baked goods – decorative elements on premium cakes, pastries, artisanal baked items
• Decorative sweets – premium candies, gourmet chocolates requiring metallic appearance
• Celebration/festive foods – special occasion foods, luxury food products
• Food decorations – edible cake toppers, food jewelry, decorative elements

Regulatory scope (severe restrictions): EU Authorization—E173 approved for surface coating of foods at “quantum satis” (unlimited amount, limited by functional needs); approved only for decorative applications. FDA (USA)—NOT approved for direct food use.

Application scope: E173 is restricted to surface coating only—making it one of the most limited food colorants. It is never used for coloring food interiors.

Why Do Food Companies Use It? (Where Approved)

E173’s primary function is providing a metallic, decorative appearance to premium foods.

Food manufacturers use aluminium powder for:

• Premium appearance: Metallic/shimmering aesthetic appeals to consumers; suggests luxury/quality
• Decorative appeal: Creates visually distinctive products that stand out on shelves
• Traditional use: Long-standing practice in premium confectionery and baked goods
• Market positioning: Metallic finish associated with gourmet/luxury food positioning
• Regulatory approval (where applicable): Approved in EU for this specific application
• No flavor impact: Doesn’t affect taste; purely cosmetic
• Cost (minimal): Small amounts needed for decorative effect

Notable: E173 is used primarily in premium, specialty, and decorative food products—not in mass-market commodity foods.

Is It Safe?

E173 is approved in the EU but highly controversial due to documented health concerns about aluminium exposure and bioaccumulation.

Regulatory approval status:

• EU: Approved as E173 for surface coating of foods (quantum satis); no specific usage limits
• FDA (USA): NOT approved for food use; classified as not permitted
• JECFA: Evaluated; no specific ADI established for aluminium metal
• EFSA: No specific ADI for aluminium metal as food additive; however, EFSA recommends limiting total aluminium from ALL sources to 1 mg/kg body weight daily

Health concerns documented in scientific literature:

• Neurotoxicity: Aluminium is recognized as a neurotoxin; affects nervous system function at high exposures
• Alzheimer’s disease link: Epidemiological evidence suggests possible association between aluminium exposure and increased Alzheimer’s risk; causality not proven but concerning; aluminium accumulates in brains of Alzheimer’s patients
• Neurodegeneration: Links suggested to ALS (amyotrophic lateral sclerosis) and other neurodegenerative diseases
• Bone health: Aluminium interferes with calcium metabolism; may weaken bones and increase fracture risk
• Kidney disease risk: People with kidney disease cannot effectively eliminate accumulated aluminium; at significantly higher risk
• Absorption and bioaccumulation: Small amounts absorbed from digestive tract; accumulates in body tissues (bone, brain, kidney) over time
• Cumulative exposure: E173 is only one aluminium source—water (especially soft water), soil-derived foods, packaging (foil, cans), cookware (aluminum pans), antacids, and other additives all contribute; cumulative exposure may exceed safe thresholds
• Vulnerable populations: Elderly, children, individuals with kidney disease at higher risk from aluminium accumulation

The Bottom Line

E173 (aluminium powder) is a metallic food colorant approved in the EU for surface decoration of foods, but it is highly controversial due to documented health concerns about aluminium toxicity and bioaccumulation. It is banned in the USA and increasingly questioned in other jurisdictions.

Key concerns: Neurotoxicity potential, possible Alzheimer’s disease links (unproven but concerning), bone health effects, kidney disease risk, bioaccumulation in body tissues, cumulative exposure from multiple aluminium sources.

Regulatory status: EU-approved for surface coating; FDA-banned; conflicting regulatory approaches reflect real safety questions.

For consumers: E173 is best avoided, particularly for children and individuals with kidney disease or family history of neurodegenerative disease. While the amount of aluminium from E173 surface coating alone is minimal, the cumulative effect of multiple aluminium exposure sources (water, packaging, cookware, antacids, other additives) may exceed safe levels. FDA’s non-approval and EFSA’s recommendation to limit total aluminium exposure suggest precaution is warranted.

Bottom recommendation: Among approved food additives, E173 warrants the highest level of caution. Choose foods without E173 decoration when alternatives available. This is one of the few food additives where avoidance is actively recommended by many health authorities, particularly for vulnerable populations. The controversy around E173 reflects legitimate scientific concerns about aluminium neurotoxicity and bioaccumulation rather than mere regulatory conservatism.