Curcumin
A yellow food colour extracted from turmeric root, used to colour mustard, margarine, ice cream and soft drinks.
High-dose curcumin supplements, especially those combined with black pepper extract (piperine), have been linked to serious liver injury and at least one death. Children eating heavily coloured diets can approach or exceed the approved daily limit. The compound in supplements and in E100 is the same one.
What is it?
Curcumin is the main pigment in turmeric (Curcuma longa). As a food additive it is produced by solvent extraction of turmeric powder followed by crystallisation to yield a concentrate containing at least 90% curcuminoids. The colour ranges from bright yellow to orange depending on the acidity of the food. It is sometimes called CI Natural Yellow 3 or Turmeric Yellow.
What does it do?
Curcumin absorbs blue-violet light and reflects yellow-orange wavelengths, giving foods a warm golden colour. It is stable in acidic conditions and is used as a colourant. At the concentrations used in food, it functions as a colour. At the far higher concentrations found in supplements, it behaves as a bioactive compound with effects on liver metabolism and iron binding.
Where you will see it
Mustard and mustard-based sauces, margarine and low-fat spreads, edible ices and ice cream, flavoured drinks and soft drinks, fine bakery products, jams and fruit preparations, processed cheese, soups, seasonings and spice blends, and snacks. On the label it appears as curcumin, E100, or turmeric extract.
What the science says
Genotoxicity and carcinogenicity
Laboratory tests have shown mixed results: curcumin caused chromosomal changes and DNA strand breaks in cell cultures at high concentrations. However, EFSA concluded in 2010 that these effects appear to occur only at concentrations far above anything achievable through food consumption, and judged curcumin to be non-genotoxic under realistic exposure conditions. JECFA reached the same conclusion. Neither body found evidence of carcinogenicity.
EFSA's ANS Panel concluded curcumin is not genotoxic at the concentrations reached through food use; chromosomal effects seen in cell-culture tests occur at concentrations two to three orders of magnitude higher than maximum in-vivo serum levels.
JECFA agreed curcumin is not carcinogenic and set an ADI of 0-3 mg/kg bodyweight per day based on a reproductive toxicity study, not a genotoxicity endpoint.
Children's exposure approaching the acceptable daily intake
EFSA carried out a refined exposure assessment in 2014 because earlier estimates suggested some children on high-consumption diets could exceed the daily intake limit of 3 mg/kg bodyweight. Using updated industry usage data, the 2014 assessment found that mean exposures in toddlers and children were below the ADI, but high-level (95th percentile) consumers in some countries reached or briefly exceeded it. The main contributing foods were flavoured soft drinks and fine bakery products. Adults, adolescents and the elderly were comfortably below the ADI in all scenarios.
At maximum permitted levels, intake estimates for 1-10 year old children at the mean and high level can exceed the ADI of 3 mg/kg bodyweight per day in some European countries.
Refined assessment using reported (real-world) use levels found high-level child and toddler exposures at or near the ADI in some surveys, with flavoured drinks and bakery products as the main contributors. Adult and adolescent exposures were below the ADI at all levels.
Liver injury from high-dose curcumin supplements
Concentrated curcumin supplements, particularly formulations that include piperine (black pepper extract) to boost absorption, have been linked to rare but serious liver injury. This is an idiosyncratic reaction, meaning it occurs unpredictably in a small subset of people, possibly those with a specific genetic variant (HLA-B*35:01). Cases reversed on stopping the supplement. The liver injury is not linked to eating turmeric as a food spice or to curcumin at food-additive doses. The UK's Committee on Toxicity reviewed this evidence and published its final assessment in December 2024.
10 cases of turmeric-related liver injury were documented by the US Drug-Induced Liver Injury Network between 2004 and 2022, all after 2011; 5 patients were hospitalised and 1 died of acute liver failure. Most cases involved high-bioavailability supplement formulations.
21 cases of acute cholestatic hepatitis potentially linked to curcumin-piperine supplements were reported in Italy between December 2018 and July 2019.
The UK Committee on Toxicity concluded there is reasonable evidence for a causal link between turmeric supplement consumption and liver toxicity. The reaction is idiosyncratic and linked in many cases to the HLA-B*35:01 genetic allele. Dietary exposure through food use or spice remains within the ADI and was not implicated.
NIH LiverTox database notes that cases overwhelmingly involve concentrated curcumin extracts with enhanced bioavailability, including piperine-based or lipid nanoparticle formulations. Traditional culinary turmeric use was not implicated. Fatal outcomes occur in roughly 10% of jaundiced supplement cases.
Interactions with medicines
At supplement doses, curcumin can interact with several medicines. The best-documented concern is with warfarin: curcumin may slow how the body clears warfarin, raising blood levels and increasing bleeding risk. Laboratory evidence also suggests interactions with some chemotherapy drugs, diabetes medicines, and drugs processed by the CYP450 liver enzyme system. Evidence for most of these interactions comes from case reports and laboratory tests, not controlled clinical trials. At typical food-additive doses, none of these interactions is a known clinical concern.
Curcumin may reduce the clearance of warfarin from the body; at least one case of elevated INR was documented in a patient combining both. The Welsh Medicines Advice Service flags this as a clinically relevant interaction requiring monitoring.
Curcumin modestly inhibits CYP3A4 and P-glycoprotein; documented interactions include elevated sulfasalazine plasma concentrations (3.2-fold) and a case of tacrolimus toxicity following high turmeric consumption.
Where it stands with the regulators
Who should be careful
People taking warfarin or other anticoagulants should avoid curcumin supplements and discuss high-turmeric diets with their prescriber, as curcumin can raise warfarin blood levels. People taking immunosuppressants (tacrolimus), sulfasalazine, or chemotherapy should also seek medical advice before using supplements. Anyone with existing liver or biliary disease should avoid concentrated curcumin supplement products. These cautions apply to supplements, not to curcumin used as a food colour (E100) at the levels found in everyday food. Look for curcumin, E100, or turmeric extract on supplement labels.
The honest read
The picture for E100 splits along dose lines, but the boundary is not as clean as regulators would prefer. As a food colour, the amounts used in products are well below the doses that produced liver injury in clinical case series. The regulatory assessment at food-additive doses is also well-established: an ADI set in 2004, confirmed in 2010, with exposure studies showing most adults come in comfortably below it. The concern that became clinically visible from around 2018 is specific to concentrated supplement formulations, particularly those using piperine or lipid nano-delivery systems to produce blood levels that diet alone could not reach. The UK Committee on Toxicity spent several years reviewing this before concluding in December 2024 that there is reasonable evidence for a link between supplements and rare liver injury. What remains less resolved is the genotoxicity picture: EFSA noted positive chromosomal signals in laboratory tests in 2010 and acknowledged its in vivo data were insufficient to fully dismiss them, while relying on carcinogenicity studies to set those concerns aside. That qualified position has not been updated since. For children eating a heavily coloured diet, high-level exposure estimates have touched or slightly exceeded the ADI in European surveys. The supplement liver injury story continues to develop.
Related additives
Common questions
Is E100 banned in the UK?
No. Curcumin (E100) is an approved food colour in the UK and EU under assimilated Regulation 1333/2008. It is authorised for use in a range of foods including drinks, bakery products, ice cream, and margarine.
Can curcumin damage the liver?
Concentrated curcumin supplements, especially those formulated with black pepper extract (piperine) to increase absorption, have been linked to rare cases of serious liver injury. At least 10 cases were documented by the US Drug-Induced Liver Injury Network between 2004 and 2022, including one death. The UK's Committee on Toxicity concluded in December 2024 that there is reasonable evidence for this link. Curcumin at food-additive levels (E100 in everyday food) has not been implicated.
What foods contain E100?
Mustard, margarine, low-fat spreads, flavoured soft drinks, ice cream and other edible ices, fine bakery products, jams, processed cheese, soups, seasonings, condiments, and some confectionery. On the label it appears as curcumin, E100, or turmeric extract.
Is E100 vegan?
Yes. Curcumin is extracted from turmeric root, a plant. It contains no animal-derived ingredients.
Sources
- UK FSA: Authorised Regulated Food and Feed Products - E-100 Curcumin
- UK FSA: Approved additives and E numbers
- EFSA ANS Panel: Scientific Opinion on the re-evaluation of curcumin (E 100) as a food additive, EFSA Journal 8(9):1679
- EFSA: Refined exposure assessment for curcumin (E 100), EFSA Journal 12(10):3876
- JECFA: Curcumin monograph 840, WHO Food Additives Series 35
- UK Committee on Toxicity: Statement COT/2024/07 on the potential risk to human health of turmeric and curcumin supplements (December 2024)
- UK Committee on Toxicity: Turmeric and Curcumin Supplements - Introduction
- NIH LiverTox: Turmeric entry, National Library of Medicine
- Hillman et al. (2023): Liver Injury Associated with Turmeric - 10 DILIN cases, The American Journal of Medicine
- Welsh Medicines Advice Service: Turmeric potential interactions
- EU Regulation 1333/2008 on food additives (assimilated in UK law)
Aaron Keen is the founder of NutraSafe. He researches and writes every additive entry himself, from the primary sources. About the research →
This is a guide, not medical advice. If an additive affects you, speak to your GP or a dietitian.
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