Annatto
A natural yellow-orange colour extracted from the seeds of the annatto tree, used to colour cheese, butter, snacks and cereals.
In people with a sensitivity to annatto, reactions including hives, swelling and in rare cases anaphylaxis have been confirmed in clinical challenge tests. Annatto is not among the 14 mandatory declarable allergens in UK law, so the label will not flag it separately.
What is it?
Annatto is a natural pigment extracted from the seeds of Bixa orellana, a tropical tree native to Central and South America. The two colouring principles are bixin (oil-soluble, found in fat-based forms) and norbixin (water-soluble, found in alkaline-extracted forms). Since January 2021 these are regulated separately as E160b(i) and E160b(ii) because they have different toxicological profiles.
What does it do?
Bixin and norbixin are carotenoid-related pigments that absorb blue-violet light and reflect yellow-to-orange wavelengths, giving foods their characteristic orange-yellow hue. Because bixin dissolves in fat and norbixin in water, manufacturers choose the form to match the product's base. The colour is stable at typical food processing temperatures.
Where you will see it
Most commonly used to colour Red Leicester, Double Gloucester, coloured Cheddar and Cheshire cheeses, as well as butter, margarine, smoked fish, breakfast cereals, savoury snacks, ready meals and some baked goods. On a UK ingredient list it appears as annatto, annatto bixin, annatto norbixin, or colour (E160b(i)) or (E160b(ii)).
What the science says
Allergic and hypersensitivity reactions
A small number of people develop reactions to annatto, ranging from hives and swelling to, in rare cases, anaphylaxis. Reactions are sometimes IgE-mediated (true immune-system allergy), likely triggered by residual seed proteins in the extract rather than the pigment molecules themselves. A 1978 open challenge study found 26% of patients with pre-existing chronic urticaria reacted to annatto, though that study lacked a placebo arm, so the true rate in the general population is much lower. A 2021 case report used a placebo-controlled oral challenge to confirm hypersensitivity in a patient who developed urticaria after annatto ingestion.
A patient developed urticaria, angioedema and severe hypotension within 20 minutes of ingesting annatto dye; IgE specific to seed proteins in the extract was identified, suggesting an IgE-mediated mechanism.
In a challenge study of 56 patients with chronic urticaria, 26% reacted to an annatto dose equivalent to that in 25g of butter; the study was not double-blind and lacked a placebo control.
Annatto hypersensitivity was confirmed in a patient by a placebo-controlled oral challenge, with urticaria as the primary symptom; the case underscores that reactions can occur outside a general allergy context.
EFSA noted that two cases of anaphylaxis from annatto ingestion had been reported in the literature up to 2016, and described severe hypersensitivity as a rare but real event.
Genotoxicity: concern raised then resolved
The 2016 EFSA opinion could not rule out a concern about DNA damage based on an in vitro comet assay result. New in vivo data submitted in 2019 showed annatto did not induce DNA damage in the liver or stomach of rats at up to 2000mg per kg body weight per day, and EFSA concluded the colour does not raise concern for genotoxicity.
A 2016 EFSA review found weak positive signals in an in vitro comet assay and could not rule out genotoxicity at that stage, noting the need for an in vivo follow-up study.
A new in vivo comet assay conducted to OECD guideline 489 under GLP found no DNA damage in rat liver or stomach at any dose; EFSA concluded annatto E does not raise concern for genotoxicity.
Norbixin exposure in children approaching its acceptable daily intake
Norbixin (E160b(ii)) has a much lower acceptable daily intake than bixin because it is more potent. EFSA's 2017 and 2019 exposure assessments found that at the 95th percentile of consumption, the norbixin ADI was approached for toddlers in some European countries. EFSA judged this to reflect a very likely overestimate of real-world intake and concluded it did not raise a health concern, but the narrow margin between the highest observed intakes and the ADI is a noted uncertainty.
EFSA set the norbixin ADI at 0.3mg per kg body weight per day, substantially lower than the bixin ADI of 6mg per kg body weight per day, reflecting different toxicological potency.
At the 95th percentile of consumption, estimated norbixin intake reached the ADI for toddlers and children in maximum-level exposure scenarios in at least one EU member state, though EFSA considered this a very likely overestimate.
Where it stands with the regulators
Who should be careful
People with a known hypersensitivity or allergy to annatto should check ingredient lists for annatto, annatto bixin, annatto norbixin, colour (E160b(i)) or colour (E160b(ii)). Annatto is not one of the 14 mandatory declarable allergens under UK food law, so it will not be highlighted in bold on ingredient lists as the major allergens are. Those with a history of chronic urticaria may be more likely to react.
The honest read
Annatto is one of the oldest natural food dyes and has a well-established pattern of use spanning centuries. For the great majority of people, exposure through food is unremarkable. The real complexity here is on two narrower fronts. First, a small subset of people, particularly those with pre-existing chronic urticaria or with a specific IgE sensitisation to annatto seed proteins, can have genuine allergic reactions; because annatto is not a listed allergen under UK law, it does not stand out on a label the way milk or nuts do, which is a practical concern for anyone who knows they react to it. Second, norbixin has a low acceptable daily intake, and EFSA found that high-consuming toddlers in some countries approached that level, though EFSA judged the gap unlikely to be a real-world problem. The genotoxicity question that existed in 2016 was resolved by 2019. The science is not live in the way it is for newer synthetic additives, but the allergy picture has genuine, documented cases attached to it.
Related additives
Common questions
Is E160b banned in the UK?
No. E160b is an approved food colour in the UK and EU. Since January 2021 it is listed as two separate entries: E160b(i) for annatto bixin and E160b(ii) for annatto norbixin. Products manufactured before that date may still carry the old E160b designation.
Can annatto cause an allergic reaction?
Yes, in a small number of people. Documented reactions include hives, swelling, and in rare cases anaphylaxis. Reactions appear to be triggered by residual seed proteins in the extract rather than the pigment itself. Annatto is not among the 14 allergens that must be declared in bold under UK food law, so it appears only in the ingredient list under its own name.
What foods contain E160b?
Most notably Red Leicester, Double Gloucester and coloured Cheddar cheeses, butter and margarine, some breakfast cereals, savoury snacks, smoked fish, ready meals and baked goods. On the ingredient list look for annatto, annatto bixin, annatto norbixin, or colour (E160b(i)) or (E160b(ii)).
Is E160b vegan?
Yes. Annatto is extracted from the seeds of the Bixa orellana plant and contains no animal-derived ingredients, unlike the insect-derived red colour carmine (E120). The colour itself is suitable for vegan diets, though the food product it colours (such as cheese) may not be.
Sources
- EFSA ANS Panel: The safety of annatto extracts (E 160b) as a food additive (2016)
- EFSA ANS Panel: Safety of annatto E and exposure to bixin and norbixin (E 160b) (2019)
- PMC: Safety of annatto E and the exposure to the annatto colouring principles bixin and norbixin (E 160b) when used as a food additive
- JECFA 52nd meeting monograph: Annatto extracts (2004)
- Nish WA et al.: Anaphylaxis to annatto dye (case report), Annals of Allergy
- Sadowska B et al.: Annatto hypersensitivity after oral ingestion confirmed by placebo-controlled oral challenge, Annals of Allergy Asthma and Immunology (2021)
- UK FSA: Approved additives and E numbers
- Commission Regulation (EU) 2020/771: splitting E160b into E160b(i) and E160b(ii)
- Regulation (EC) No 1333/2008 Annex II (as retained 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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