Red 3

A bright cherry-red synthetic color (erythrosine) used to tint candies, cherries, icings, and some drugs. It’s an iodinated xanthene dye.

Should I eat Red 3?

Red 3 is a highly refined, iodine‑rich synthetic dye that FDA is phasing out of U.S. foods; it should be off food labels by January 15, 2027. If it appears on a product you’re considering—especially if you track thyroid function—choose an option using beet or fruit/vegetable colors instead.

Summary

Red 3 (erythrosine) is a bright cherry‑red synthetic dye made from petroleum‑derived organics and iodine. On January 15, 2025, FDA revoked its authorization for foods and ingested drugs, with food compliance due January 15, 2027 and drug compliance due January 18, 2028. The cancer signal comes from high‑dose male‑rat thyroid tumors; reviews note this is a thyroid‑hormone effect in rats and that Red 3 is non‑genotoxic. A small human study found a rise in TSH only at 200 mg/day, far above typical diet exposures; global bodies maintain a cautious ADI of 0–0.1 mg/kg/day. If you want to avoid synthetic dyes—or have thyroid concerns—scan labels and favor products colored with beet or fruit/vegetable extracts.

Key Research Points

U.S. use revoked; deadlines set

On January 15, 2025, FDA moved to remove Red 3 from foods and ingested drugs under the Delaney Clause. Foods must comply by January 15, 2027 and ingested drugs by January 18, 2028, so it should appear less on shelves over time.

Rat thyroid tumors at high doses

Lifetime studies found thyroid tumors in male rats at very high dietary doses. Regulators explain this as a thyroid‑hormone–driven rat effect and note Red 3 does not damage DNA (non‑genotoxic).

Thyroid effects at very high intake

In a small human study, 200 mg/day raised TSH (a pituitary signal to the thyroid), while 20–60 mg/day did not. Reviews keep a conservative ADI of 0–0.1 mg/kg/day and estimate usual food exposure is well below that.

Overview

What is it?

Source: Petroleum-derived organics; iodine salts

Method: Iodinate fluorescein, then refine

Processing Level: 10 / 10

Why is it used?

Purpose: Synthetic red color used mainly to give a vivid cherry-red hue.

Commonly found in: Candies, Maraschino cherries, Frostings, Ice pops, Pills

Why manufacturers choose it: Very bright, shade-consistent red that’s stable and inexpensive at low doses.

Origin

Erythrosine (FD&C Red No. 3; E127) was introduced in the late 1800s as a red-pink derivative of fluorescein and quickly spread from textiles to foods and drugs. The US formally listed it for foods and ingested drugs in 1969. In 1990, the FDA curtailed some cosmetic/topical uses. In January 2025, the FDA revoked its authorization in foods and ingested drugs under the Delaney Clause (because it caused thyroid tumors in male rats at high doses), setting multi-year phase-out dates. In the EU and UK, use has long been tightly restricted (notably to certain preserved cherries).

Process: Iodinate fluorescein, then refine

Steps

1. Synthesize fluorescein: Condense phthalic anhydride with resorcinol to make fluorescein.

2. Iodination: Introduce iodine atoms to fluorescein (e.g., iodine/iodic acid or KI/I2) to form tetra-iodinated dye.

3. Neutralize & salt: Convert to disodium salt for solubility and stability.

4. Purify: Remove by-products and salts; dry and mill to fine powder.

Chemicals

Phthalic anhydride

Resorcinol

Iodine

Iodic acid or iodide/oxidant system

Ethanol/water (reaction medium)

Research & Safety

Potential Concerns

The strongest signal is thyroid tumors in male rats at very high doses; FDA therefore revoked food and ingested‑drug uses under the Delaney Clause, setting phase‑out dates in 2027–2028. In humans, a short study found TSH increases at 200 mg/day, but no changes at 20–60 mg/day; everyday intakes are orders of magnitude lower. EFSA and JECFA maintained an ADI of 0–0.1 mg/kg bw/day and consider the rat mechanism to have limited human relevance, yet some regions strictly limit uses as a precaution. Consumers who wish to avoid synthetic dyes or who have thyroid conditions may choose products made with alternative reds.

Potential Benefits

No demonstrated nutrimental benefit

Digestive Effects

There are no consistent GI side effects tied specifically to Red 3 at typical food‑level exposures in controlled evaluations. Synthetic dyes can cause nonspecific symptoms in some people anecdotally, but robust clinical evidence for Red 3–specific digestive effects is lacking. Overall exposure from foods has been estimated to be far below the ADI in population assessments. People who notice reproducible symptoms with dyed foods can try elimination and re‑challenge under clinician guidance.

Limit Consumption

Children often consume dyed sweets; although exposure estimates are generally below the ADI, U.S. approvals are being revoked and products are being reformulated, so labels may change through January 2027. People with thyroid disease, iodine sensitivity, or those on thyroid medication may prefer to avoid Red 3 because high doses can alter TSH and raise iodide, potentially affecting labs. In the EU/UK, uses are tightly restricted (notably preserved cherries), and imported products must comply with local rules. If you are pregnant, breastfeeding, or managing thyroid conditions, choose products without Red 3 or consult your clinician if you have concerns.

Fact Sheet

Regulatory Status

US FDA: Revoked for foods and ingested drugs (order dated Jan 15, 2025). Compliance: food by Jan 15, 2027; ingested drugs by Jan 18, 2028.

EU Status: Permitted with strict limits (notably preserved cherries) per EU re-evaluation; broader use generally not allowed.

Codex INS: INS 127 (Erythrosine). Category-specific MPLs in Codex GSFA.

JECFA ADI: 0–0.1 mg/kg bw/day.

ESG & Sustainability

Environmental Footprint: Petrochemical/industrial synthesis plus iodine sourcing; very low dose per serving limits total footprint but not inherently ‘natural’.

Sustainability: Synthetic production avoids agricultural land use but relies on fossil-derived feedstocks and mined iodine.

Animal Welfare: Vegan (synthetic). Carmine alternative is insect-derived.

Carbon Footprint: No high-quality LCA specific to erythrosine found; per-serving impact is small due to ppm use.