What is E155?

Complete guide to understanding E155 (Brown HT / Chocolate Brown HT) – the synthetic brown azo dye with controversial status

The Quick Answer

E155 is Brown HT (also called Chocolate Brown HT or Food Brown 3)—a synthetic brown azo dye derived from coal tar used as a food colorant to substitute for cocoa or caramel coloring. It’s a bis-azo dye containing two linked nitrogen atoms, belonging to the same synthetic dye family as tartrazine (E102) and other synthetic food colorants.

E155 is used to color foods brown, primarily chocolate-flavored products like cakes, desserts, dairy products (yogurt, cheese, ice cream), and chocolate drinks. It provides excellent color stability at high temperatures (hence the “HT” designation for “high temperature”) and resistance to light degradation—making it ideal for processed foods.

Critically, E155 has a highly controversial regulatory status: It is approved in the European Union and some countries (Australia, New Zealand, India), but it is BANNED in Canada, the United States, and numerous European countries (Austria, Belgium, Denmark, France, Germany, Norway, Sweden, Switzerland). The divergent regulatory approach reflects ongoing safety concerns about this synthetic dye, particularly regarding allergic reactions, hyperactivity in children, and potential health risks identified in various research.

What Exactly Is It?

E155 is a synthetic azo dye—a chemical compound containing two linked nitrogen atoms (N=N) as part of its molecular structure, derived from coal tar through multi-step chemical synthesis. It’s not extracted from natural sources or made through fermentation, but rather synthesized entirely from petroleum/coal tar derivatives through complex organic chemistry.

Think of E155 as part of the synthetic dye family—similar in many ways to tartrazine (E102, yellow dye), allura red (E129, red dye), and other azo dyes. These synthetic dyes were developed in the mid-20th century to provide consistent, stable colors for food manufacturing where natural colorings proved inadequate.

Key characteristic: E155 is a fully synthetic compound—not derived from natural sources. This fundamentally distinguishes it from plant-based or mineral-based colorings. While synthetic dyes provided advantages (stability, brightness, consistency), the regulatory backlash against many synthetic dyes reflects accumulating safety concerns, of which E155 is among the most controversial.

Chemical identity:

• Chemical class: Bis-azo dye (contains two azo linkages: -N=N-)
• Full chemical name: Disodium 4,4′-(2,4-dihydroxy-5-hydroxymethyl-1,3-phenylene-bisazo) di-1-naphthalene-sulfonate
• Molecular formula: C₂₇H₁₈N₄Na₂O₉S₂
• Azo linkages: Two -N=N- bonds; chromophore responsible for color
• Aromatic rings: Multiple naphthalene and benzene rings in structure
• Sulfonate groups: SO₃⁻ groups providing water solubility
• Sodium salts: Disodium salt form used in food (Na⁺ counter-ions)

How it’s made:

E155 is produced through multi-step synthetic chemistry from coal tar derivatives:

• Starting materials: Aromatic amines (e.g., aniline derivatives), sulfonic acid derivatives, naphthol compounds, resorcinol derivatives
• Diazotization: Aromatic amine treated with sodium nitrite and hydrochloric acid to form diazonium salt
• Azo coupling: Diazonium compound coupled with aromatic nucleophiles (coupling agents) to form azo (-N=N-) bonds
• Sulfonation: Product sulfonated to add solubilizing sulfonate groups
• Sodium salt formation: Product converted to sodium salt for water solubility
• Purification: Final product purified through filtration, crystallization, drying; typical purity ≥70% dye content
• Chemical synthesis: Entirely synthetic; no natural sources or fermentation involved

Where You’ll Find It

E155 appears in brown-colored foods, but with MASSIVE regional variation in approval:

Primary Food Applications (Where Approved):

• Chocolate cakes and baked goods (PRIMARY USE) – provides brown color; excellent heat stability for baking
• Chocolate milk and chocolate drinks – particularly in Australia (very common)
• Confectionery (candies, desserts) – chocolate-flavored sweets
• Dairy products – yogurt, cheese, ice cream (where approved)
• Desserts and puddings – brown/chocolate-colored items
• Baked goods generally – cookies, pastries, breads with brown coloring
• Jams and fruit products – where brown color enhancement desired
• Sauces and condiments – brown coloring
• Fish and processed meats – limited applications
• Breakfast cereals – brown-colored cereals

Regulatory scope and regional variation:

• EU: Approved; used in multiple food categories with specified limits (~50-200 mg/kg maximum)
• Australia/New Zealand: Approved; extremely common in chocolate milk
• India: Approved for limited use
• USA: BANNED; FDA has not approved for food use
• Canada: BANNED
• Austria, Belgium, Denmark, France, Germany, Norway, Sweden, Switzerland, Russia: BANNED despite EU approval

Primary food application (where approved): E155 is most extensively used in chocolate-flavored products and baked goods in Australia and parts of Europe where it’s approved.

Why Do Food Companies Use It? (Where Approved)

E155’s advantages are primarily technical: excellent heat and light stability making it ideal for processed foods. However, the extensive bans and safety concerns have dramatically reduced its use even in approved jurisdictions.

Food manufacturers (in approved regions) use E155 for:

• Heat stability: Maintains brown color even after baking, cooking, or high-temperature processing
• Light stability: Doesn’t fade during shelf storage under store lighting
• Consistency: Provides uniform, consistent brown color (unlike natural cocoa)
• Cost: Relatively inexpensive synthetic dye
• Bright color: Produces vibrant brown color
• Processing flexibility: Can be used in products exposed to heat and light
• Regulatory approval (where applicable): Permitted in EU and some other jurisdictions

Is It Safe?

E155 has the most controversial safety profile of modern food colorants, with serious safety concerns documented and divergent regulatory risk assessments globally.

Regulatory approval status:

• EU: Approved (2010 EFSA re-evaluation) with specified limits; however, multiple member states ban despite EU approval
• FDA (USA): NOT approved for food use; concerns about possible health risks identified
• Health Canada: NOT approved; safety concerns cited
• JECFA: Evaluated; ADI of 1.5 mg/kg established (though interpretation varies)
• Australia: Currently approved; widely used
• Multiple countries: Despite EU approval, banned in Austria, Belgium, Denmark, France, Germany, Norway, Sweden, Switzerland, Russia

Health concerns documented in literature:

• Allergic reactions: Can cause hypersensitivity reactions in people with asthma, aspirin intolerance, and other sensitive individuals; documented cases of skin reactions (rash, eczema, hives)
• Hyperactivity in children: Research suggests artificial food colorants (including azo dyes like E155) may contribute to hyperactivity/behavioral issues in some children; disputed but concerning
• Carcinogenic concerns: EFSA noted “discrepancies and uncertainties” in available data regarding carcinogenic potential; flagged as area requiring further evaluation
• Azo dye class issues: As member of azo dye family, E155 shares structural characteristics with other controversial colorants (tartrazine E102, allura red E129)
• Systemic absorption: Unlike natural colorings, synthetic azo dyes can be absorbed and metabolized systemically
• Azo dye metabolism: In the colon, gut bacteria can cleave azo bonds (-N=N-) producing potentially toxic breakdown products

Bottom Line on Safety

E155 Safety Assessment:

• EU regulatory position: Approved with maximum usage limits; considered acceptable at regulated levels
• Global regulatory consensus: ABSENT—with serious disagreement between jurisdictions suggesting real safety questions
• Specific concerns: Allergic reactions in sensitive individuals (fairly well-documented); hyperactivity in children (debated); potential carcinogenic risk (EFSA noted uncertainties)
• Absorption and metabolism: Unlike natural colorings, E155 is absorbed and metabolized; gut bacteria cleave azo bonds potentially producing harmful metabolites
• Safety data: Limited toxicological studies compared to other approved colorants
• Risk-benefit assessment: Where natural or safer alternative colorings available (cocoa, caramel, natural brown colorings), avoiding E155 represents precautionary approach
• Vulnerable populations: Individuals with asthma, aspirin sensitivity, or families with history of food dye reactions should particularly avoid E155

Comparison: E155 vs Other Brown Colorings

Colorant	Type	Heat Stability	Safety Profile	Regulatory Status
E155 (Brown HT)	Synthetic azo dye	Excellent	Controversial; allergic/hyperactivity concerns	Approved EU; Banned USA/Canada/many others
Natural cocoa	Natural plant extract	Good	Excellent; long history	Approved everywhere
Caramel (E150)	Natural/semi-natural	Good	Very good; some classes have concerns	Approved worldwide
E172 (Iron Oxides)	Mineral pigment	Excellent	Excellent; not absorbed	Approved worldwide

The Bottom Line

E155 (Brown HT / Chocolate Brown HT) is a synthetic brown azo dye used to color chocolate-flavored foods and baked goods. It provides excellent heat and light stability making it useful for processed foods, but it is one of the most controversial food colorants with serious safety questions.

Key concerns: Allergic reactions (especially in sensitive individuals), potential hyperactivity in children (debated), carcinogenic uncertainty (EFSA noted discrepancies), azo dye metabolism producing potentially harmful metabolites.

Regulatory status: Approved in EU and some other jurisdictions; BANNED in USA, Canada, Austria, Belgium, Denmark, France, Germany, Norway, Sweden, Switzerland, Russia—reflecting unprecedented regulatory disagreement.

For consumers: If you have asthma, aspirin sensitivity, or sensitivity to food colorants—strongly avoid E155. For general population, the existence of safer alternatives (natural cocoa, caramel, iron oxides) suggests precautionary avoidance is reasonable, particularly for children. The global regulatory divergence (approval in some jurisdictions, bans in others) suggests genuine safety questions exist, even if some regulators deem the risks acceptable at specified limits.

Bottom recommendation: Among modern food colorants, E155 warrants the highest caution. Unlike most approved additives where regulatory consensus exists, E155 shows major divergence with multiple developed countries banning it. For consumers seeking to limit potentially problematic additives, E155 should be a priority for avoidance where alternative products available.