E133 – Brilliant Blue FCF | blue food dye side effects and uses

Quick analysis summary about E133 – Brilliant Blue FCF food additive

Bottom line about E133

E133 is a synthetic blue food colour also known as Brilliant Blue FCF or FD&C Blue No. 1, graded ORANGE – SOME CONCERNS.

Why this grade for E133

The ADI basis is reassuring, but newer gut-microbiome evidence, synthetic dye policy shifts, and sensitivity concerns make GREEN too strong.[1-5]

Who may want to limit or avoid E133

Children sensitive to artificial colours, people with dye intolerance, and frequent consumers of brightly coloured sweets or drinks may limit E133.

Common uses and where E133 appears

E133 appears in blue confectionery, drinks, icings, desserts, snack decorations, and novelty foods.

E133 source or origin

E133 is a synthetic triarylmethane dye made from industrial aromatic chemical intermediates and purified for food use.

Intake note for E133

ADI (Acceptable Daily Intake) is 6 mg/kg body weight per day, based on a chronic rat study and an uncertainty factor of 100.[1]

Is E133 banned anywhere?

E133 is authorised in the EU and FD&C Blue No. 1 is still federally listed for food use in the US. The FDA is working with industry to eliminate Blue No. 1 from the US food supply by the end of 2027, and California public schools must remove Blue 1 from covered school foods from December 31, 2027.

Safety grading ORANGE – SOME CONCERNS

E133 – Brilliant Blue FCF is not graded RED because it remains authorised in the EU and federally permitted in the US, and oral toxicology data do not show clear genotoxicity or carcinogenicity at normal dietary exposure.[1,2] It is not graded GREEN because it is a non-essential synthetic dye with a recent direct gut-microbiome signal, broader synthetic dye concern in some children, and a current US policy push toward removal from food products.[4,5]

Study basis or key toxicological reasoning for E133

EFSA used a NOAEL (No Observed Adverse Effect Level) of 631 mg/kg body weight per day from a chronic rat study to set an ADI of 6 mg/kg body weight per day.[1] Lifetime dietary studies in Charles River CD rats and CD-1 mice did not show treatment-related carcinogenicity, while toxicokinetic work in rats, mice, and guinea pigs found poor gastrointestinal absorption and mainly faecal excretion.[2,3] The main uncertainty is newer evidence outside the older ADI basis. A 2025 in vitro simplified human microbiota model reported persistent structural and functional microbiome changes after Brilliant Blue exposure, while human enteral-feeding case reports show that systemic absorption can matter in critically ill patients with compromised gut barriers, although that scenario is indirect for ordinary food use.[5,6]

Side effects of E133 – Brilliant Blue FCF food additive

Possible sensitivity reactions: Rare intolerance or allergy-like reactions are possible with synthetic dyes, although E133-specific dietary reactions are not common.
Child behaviour concern: Activity and attention evidence concerns synthetic dyes as a group, not E133 alone.[4]
Gut microbiome uncertainty: A direct in vitro study found persistent microbiome changes after Brilliant Blue exposure.[5]
High-risk medical absorption context: Critically ill tube-fed patients are not a normal food-use model, but cases show why gut-barrier status matters.[6]
Excess highly coloured foods: High intake usually comes from sweets, drinks, and desserts, so exposure can track with a less nutritious diet.

Should You Avoid E133 – Brilliant Blue FCF food additive?

Occasional E133 exposure in regulated foods is unlikely to be a major risk for most adults. Avoidance is more reasonable for children who appear sensitive to synthetic colours, people with previous dye reactions, and households trying to reduce highly coloured ultra-processed foods. The ORANGE grade means caution and monitoring, not proof that every normal exposure is harmful. Choosing uncoloured products or foods coloured with simpler ingredients is the easiest way to reduce exposure.

Common uses of E133 – Brilliant Blue FCF food additive

Blue sweets and confectionery, where it gives a bright blue colour.
Soft drinks, sports drinks, and drink mixes with blue or purple shades.
Icings, cake decorations, and dessert toppings where strong colour is part of the appeal.
Frozen desserts, ice pops, and novelty foods where colour helps product recognition.
Snack coatings and decorative sprinkles, depending on local category permissions.
Colour blends with yellow dyes, where it can help create green tones.

Common names and synonyms of E133 – Brilliant Blue FCF food additive

E133
Brilliant Blue FCF
FD&C Blue No. 1
Blue 1
Acid Blue 9
C.I. 42090
Food Blue 2
INS 133

What is E133 – Brilliant Blue FCF food additive?

E133 – Brilliant Blue FCF is a water-soluble synthetic blue dye from the triarylmethane family. Manufacturers use small amounts to produce a strong blue colour, and it can be blended with other colours to make green, purple, or darker shades. It has no nutritional function. Its purpose is visual, mainly to make products look more attractive or recognisable.

Food-grade Brilliant Blue FCF is produced by chemical synthesis and refined to meet specifications for colouring strength, salts, subsidiary colours, and impurity limits. Older safety assessments focused on animal feeding studies, genotoxicity, carcinogenicity, reproductive studies, and exposure estimates. Newer research is asking whether poorly absorbed dyes may still interact with the gut microbiome before leaving the body.

Where is E133 – Brilliant Blue FCF food additive allowed (EU vs US)?

In the EU, E133 is authorised as a colour in selected food categories under maximum level rules and purity specifications. In the US, FD&C Blue No. 1 is permanently listed for food use with batch certification and good manufacturing practice limits. The current US direction is changing because FDA is working with industry to remove Blue No. 1 and other petroleum-based certified dyes from food by the end of 2027.

E133 – Brilliant Blue FCF