Gold
Metallic gold in flake, leaf or powder form, used to decorate the surface of chocolates, confectionery and some liqueurs.
EFSA could not complete a full risk assessment in 2016 due to insufficient toxicity data. Food-grade gold powder contains nanoparticles, and animal studies show those particles can alter gut bacteria and intestinal immune responses, with female animals showing greater susceptibility.
What is it?
Elemental gold (chemical symbol Au) used at 22-24 carat purity. It comes as beaten leaf, flakes, or fine powder and is classified as a colour additive because it gives food a metallic gold appearance. It has no flavour or nutritional function.
What does it do?
Coats the outer surface of food to give a shiny, metallic gold finish. Gold is chemically inert under normal conditions, so it does not react with food, release flavour compounds, or dissolve in water. The human body cannot digest or metabolise it, and it passes through the gut largely unchanged. In powder form, however, the particles include a fraction at nanoscale dimensions (below 100 nm in at least one dimension), and those smaller particles behave differently from bulk metal.
Where you will see it
Decorative chocolate truffles, gold-dusted confectionery, celebration cakes, luxury biscuits, and gold-flake liqueurs such as Goldschlager and Danziger Goldwasser. It is a prestige ingredient used for visual effect rather than taste. On an ingredient list, look for 'Gold' or 'E175'.
What the science says
EFSA could not complete a standard risk assessment
When EFSA re-evaluated E175 in 2016, it found no subchronic or chronic toxicity studies and no genotoxicity data on elemental gold used as a food additive. The panel considered the data too limited to carry out a conventional risk assessment and did not set a numerical acceptable daily intake. It concluded that systemic effects were unlikely given gold's low solubility, but acknowledged this was a qualitative judgement rather than a data-driven one.
The Panel noted the limited data on absorption, distribution, metabolism and excretion of elemental gold and the absence of toxicological data on E 175, and considered the data too limited to perform a risk assessment.
No numerical ADI was established. The Panel concluded that systemic availability of elemental gold would not be expected given its low solubility, but this conclusion rested on the absence of observed effects rather than positive toxicological evidence.
Nanoparticles are present in food-grade gold powder
Food-grade gold leaf and powder are not uniform bulk metal: the thinnest dimensions of the flakes and a measurable fraction of powder particles fall below 100 nm. EFSA recommended that specifications for E175 should include mean particle size, particle size distribution, and the percentage of particles in the nanoscale, information that was not systematically available at the time of the 2016 opinion. Separate analytical work confirmed that gold nanoparticles with a dominant size around 124 nm can be extracted from commercial gold-flake liqueurs.
EFSA recommended that E175 specifications must include mean particle size, particle size distribution, and the percentage (by number) of particles in the nanoscale with at least one dimension below 100 nm, for the powder form.
Gold nanoparticles ranging from 8.3 to 398 nm were detected in a commercial gold-flake liqueur; over 69% of particles by count were below 100 nm.
Animal study found gut and immune changes at relevant doses
A 90-day study fed mice food-grade E175 at doses spanning the range estimated for human exposure. No liver or intestinal tissue damage was found, and genotoxicity tests were negative. However, female mice showed altered gut bacteria composition, increased markers of intestinal inflammation, and reduced production of short-chain fatty acids at higher doses. Male mice showed the opposite immune pattern. The authors concluded the alterations were mostly non-toxic within the human dose range but called for toxic reference values to be established for safe use.
90-day oral exposure to food-grade E175 at 0.1, 1, and 10 micrograms/kg body weight/day altered gut microbiota composition and intestinal immune responses in mice in a sex-dependent manner; female mice showed gut dysbiosis and low-grade intestinal inflammation at higher doses.
No histomorphological damage to the liver, spleen, or intestine was observed, and genotoxicity tests in the colon and liver were negative, but the authors recommended establishing toxic reference values for gold as a food additive.
Gold nanoparticle studies in rats raise reproductive questions
Several laboratory and animal studies using synthesised gold nanoparticles (not necessarily food-grade E175) have found accumulation in testicular tissue, reduced testosterone production, and impaired sperm quality in male rodents. These studies used intravenous or other non-dietary routes of administration and particle characteristics that may not reflect actual dietary exposure from E175, so they cannot be read across directly. They nonetheless identify a potential hazard pathway that has not been investigated in the context of food use.
Gold nanoparticles (5 nm, intravenous) accumulated in Leydig cells of mouse testes, reducing testosterone production by down-regulating 17alpha-hydroxylase and impairing epididymal sperm quality.
Reproductive toxicity studies in male rats exposed to gold nanoparticles showed testicular damage and histopathological changes; the authors noted the question of reversibility remained open.
Where it stands with the regulators
Who should be careful
There are no declared allergens associated with gold and no current regulatory restriction on any population group. People with rheumatoid arthritis who take injectable gold-salt medicines should note that ionic gold (released when elemental gold contacts tissue) has pharmacological effects, though dietary exposure to ionic gold from E175 at typical use levels is very low. Anyone wishing to minimise exposure to a substance with an unresolved safety dossier should check ingredient lists for 'Gold' or 'E175', particularly on decorated chocolates, celebration confectionery, and premium liqueurs.
The honest read
Edible gold has a very long history of use and elemental gold is chemically unreactive, which is why regulators have kept it on the permitted list. The honest picture, though, is that the safety dossier has a real gap: EFSA's 2016 re-evaluation did not have adequate toxicity data to run a conventional assessment and set no ADI. The key emerging question is nanoparticles. Food-grade gold powder and thin flakes contain particles in the nanometre range, and nanoscale gold behaves differently from the bulk metal. A 2023 animal study found that female mice showed gut bacteria changes and intestinal immune responses at doses spanning the human exposure range. The science here is live, not settled.
Related additives
Common questions
Is E175 banned in the UK?
No. Gold (E175) is on the UK's approved additives list (assimilated EU Regulation 1333/2008). It is permitted specifically for the external coating of confectionery, decoration of chocolate products, and liqueurs.
Why did EFSA not set an ADI for gold?
When EFSA re-evaluated E175 in 2016, it found no subchronic or chronic toxicity studies and no genotoxicity data had been conducted on food-grade elemental gold. The panel considered the available information too limited to run a standard risk assessment and therefore could not establish a numerical acceptable daily intake. It applied a qualitative judgement based on gold's low solubility rather than positive toxicological evidence.
What foods contain E175?
Gold is used as a decorative surface coating on premium chocolates and confectionery, celebration cakes, and gold-flake liqueurs such as Goldschlager and Danziger Goldwasser. It appears as 'Gold' or 'E175' in the ingredient list.
Is E175 vegan?
Gold is a mineral element with no animal-derived components. Most vegan certification bodies do not exclude it. Individual vegan consumers can verify by checking whether any carrier or processing aid used with the gold product involves animal-derived substances.
Sources
- EFSA Panel on Food Additives and Nutrient Sources, Scientific Opinion on the re-evaluation of gold (E 175) as a food additive, EFSA Journal 14(1):4362 (2016)
- UK Food Standards Agency: Approved additives and E numbers
- Quaranta et al., A 90-day oral exposure to food-grade gold at relevant human doses impacts the gut microbiota and the local immune system in a sex-dependent manner in mice, Particle and Fibre Toxicology 20:31 (2023)
- Determination and Characterization of Gold Nanoparticles in Liquor Using AF4-ICP-MS, PMC10780710 (2024)
- European Commission call for scientific and technical data on the permitted food additive gold (E175), 2018
- EFSA follow-up re-evaluation of silver (E174) as a food additive, EFSA Journal 23(4):9316 (2025) - parallel regulatory context for metallic colour additives
- Edible gold, Wikipedia (background and historical context)
- EU Regulation (EC) No 1333/2008 on food additives (consolidated 2024)
- The Effects of Gold Nanoparticles on Leydig Cells and Male Reproductive Function in Mice, International Journal of Nanomedicine Vol 15 (2020), PMID 33281445
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