Red No. 40 out, beet juice in? What food dye 'upgrades' mean for your patients

For decades, synthetic food dyes have colored our food supply with a vibrant, albeit artificial, spectrum. Yet a growing body of evidence has cast a long shadow over their purported ‘safety.’ 

As a result, the FDA has recently moved to discontinue the use of several petroleum-based dyes.

In a landmark decision reflecting the culmination of this scientific scrutiny, the FDA announced in April 2025 that authorization for two synthetic food colorings would be revoked in the next few months, and the use of six others would be phased out. ^[] Here are the six food dyes that will be phased out.

Blue No. 1 and No. 2

FD&C Blue No. 1 (Brilliant Blue FCF) is a petroleum-derived dye used in products like M&Ms and Takis chips.

Animal data remain limited, but one (unpublished) animal study suggested a small cancer risk. Preliminary in vitro research has also raised concerns about potential neurotoxicity, prompting calls for further testing. ^[]

FD&C Blue No. 2 (Indigo Carmine) is a synthetic dye used to replicate the color of natural indigo in foods like Skittles and blueberry Pop-Tarts.

Studies in male rats have reported an increased incidence of brain gliomas following exposure. A 2021 paper from Polish researchers concluded that Blue No. 2 should not be regarded as safe for human use. ^[]

Studies show it may have antioxidant, anti-inflammatory, antidepressant, and nerve-regenerative effects, relevant for oncology, given the roles of inflammation, oxidative stress, and nerve damage in cancer care. ^[]

Butterfly pea flower extract, approved in May 2025, contains anthocyanins with strong antioxidant activity. ^[] Research links it to improved LDL resistance, glycemic control, weight regulation, and anxiolytic effects. ^[]

Supporting the push to restrict synthetic food dyes, Lisa Lefferts, a senior scientist at the Center for Science in the Public Interest, says: “If you talk to parents whose kids are sensitive to dyes, they'll tell you how difficult it is to avoid dyes and what a huge change it was for their entire household to try to get these dyes out of their kids' diets.” ^[]

Red No. 3 and No. 40

FD&C Red No. 3, or erythrosine, a food dye with a distinctive cherry-red hue, has long been a ubiquitous presence in a variety of food products, especially confections.

However, several animal studies from the 80s and 90s demonstrated an association between high-level exposure to Red No. 3 and the development of thyroid tumors in male laboratory rats. ^[]

But short-term human studies (up to 3 weeks) revealed no consistent alterations in thyroid hormones (TSH, T3, T4) at typical exposure levels. ^[]

Nevertheless, given rising concerns, in January 2025, the FDA banned the use of Red No. 3 in food and ingested drugs. ^[]

As per the FDA statement, "manufacturers who use FD&C Red No. 3 in food and ingested drugs will have until January 15, 2027, or January 18, 2028, respectively, to reformulate their products." ^[]

Another synthetic red food dye, FD&C Red No. 40, or Allura Red AC, has not been as extensively implicated in direct carcinogenesis in animal models. This distinction has, perhaps misleadingly, led some to perceive it as a “safer” alternative among synthetic agents. 

However, a recent study found that Red 40 causes DNA damage, triggers low-grade colonic inflammation, and disrupts the gut microbiome in mice. ^[] When combined with a high-fat diet over 10 months, these effects were amplified.

Furthermore, California’s OEHHA review also reaffirmed that Red 40 is implicated in adverse behavioral outcomes such as irritability, restlessness, and inattention in a susceptible subset of children. ^[]

Givaudan Sense Colour, a producer of natural food and beverage colorants, identified three alternatives to synthetic red food dyes: carmine (insect-derived), betacyanins (from beets), and anthocyanins (from fruits and vegetables). ^[]

Meanwhile, California assembly member Jesse Gabriel told NBC News that although synthetic dyes are typically cheaper, the Red No. 3 ban is not expected to raise food prices. ^[]

Yellow No. 5 and No. 6

Used in products like Mountain Dew and Twinkies, FD&C Yellow No. 5 (tartrazine) is a synthetic dye associated with DNA damage, inflammation, and hyperactivity in children. ^[]

Similarly, FD&C Yellow No. 6 (Sunset Yellow FCF), found in foods like Lucky Charms, may be contaminated with benzidine, a potential carcinogen, during production. Studies have linked both dyes to behavioral effects in children and allergic responses. ^[]

Although no new yellow‑hued natural dyes have been approved recently, existing natural yellows, namely annatto extract and β‑carotene, remain permanently listed and exempt from certification, and are widely used.