Blue 1 (Brilliant Blue): What You Need to Know

Blue 1, known commercially as Brilliant Blue FCF, is the primary synthetic blue colorant in the American food supply. This petroleum-derived dye creates the vivid blue hues in sports drinks, candies, ice cream, and countless other products—as well as serving as a component in green-colored foods when combined with yellow dyes. While perhaps less scrutinized than its red and yellow counterparts, Blue 1 has attracted growing research attention for its potential neurobehavioral effects and impacts on gut health.

As one of the six synthetic dyes targeted by the FDA's voluntary phase-out initiative, Blue 1 is an important part of the ongoing reassessment of petroleum-based food colorants. This guide examines what Blue 1 is, where it's found, the evolving scientific understanding of its health effects, and natural alternatives for consumers seeking to avoid synthetic blue dyes.

What Is Blue 1 (Brilliant Blue FCF)?

Blue 1 is a synthetic triphenylmethane dye derived from petroleum.^[1] Unlike azo dyes such as Red 40 and Yellow 5, which contain nitrogen-nitrogen double bonds, Brilliant Blue belongs to a different chemical class characterized by a central carbon atom bonded to three aromatic rings. This structural difference gives Blue 1 its distinctive bright blue color and somewhat different metabolic properties compared to azo dyes.

The dye produces an intense, vibrant blue that remains stable across a wide range of pH levels and temperatures, making it highly versatile for food manufacturing applications. Its excellent water solubility allows easy incorporation into beverages and other water-based products. Blue 1 can also be converted to a "lake" form (an insoluble pigment) for use in products where water solubility is not desired, such as coated candies and confections.

Blue 1 has applications beyond food coloring. In medical settings, a diluted form (Patent Blue V, a close relative) has been used as a diagnostic dye for mapping lymph nodes during cancer surgery. This medical application has provided some safety data on the dye's behavior in the body, though at much higher doses than typical dietary exposure.

Where Is Blue 1 Found?

Blue 1 appears in a broad range of products, often in ways consumers might not immediately recognize. Direct blue-colored products include sports drinks and energy drinks, blue candies and confections, ice cream and frozen desserts, blue-flavored beverages ("blue raspberry," etc.), popsicles and frozen treats, blueberry-flavored products, and certain cake decorating supplies.

Notably, Blue 1 is extensively used in combination with Yellow 5 or Yellow 6 to create green colors. This means many green-colored foods—from mint ice cream to lime candies to certain pickles—contain Blue 1 even though they don't appear blue.^[2] Consumers seeking to avoid Blue 1 must therefore look beyond obviously blue products.

Beyond food, Blue 1 is found in medications, dietary supplements, vitamins (particularly children's gummy vitamins), mouthwash, toothpaste, and various cosmetics including hair dyes and eye makeup. Its presence in oral care products is particularly notable given the direct exposure to mouth tissues.

Regulatory Status Around the World

Blue 1's regulatory treatment differs from some of its fellow synthetic dyes in important ways:

United States: Blue 1 is authorized under 21 CFR §74.101 and is included in the FDA's April 2025 voluntary phase-out initiative, with industry working toward elimination by the end of 2027.^[3] Prior to this initiative, Blue 1 was generally considered one of the "safer" synthetic dyes by U.S. regulators.
European Union: Authorized as E133. Unlike Red 40, Yellow 5, and Yellow 6, Blue 1 does NOT require mandatory warning labels in the EU.^[4] This is because Blue 1 was not included in the Southampton Study^[5] dye mixtures that triggered the EU warning label requirement.
United Kingdom: Authorized under E-number system without warning label requirement.
Canada: Permitted on the List of Permitted Food Colours.
Japan: Listed as a designated food additive under the name "Food Blue No. 1."

The lack of EU warning label for Blue 1 sometimes leads to the misconception that it is "safer" than the labeled dyes. In reality, the absence of a warning label reflects Blue 1's exclusion from the Southampton Study rather than comprehensive evidence establishing its safety relative to other synthetic dyes.

Health Concerns: Emerging Research

While Blue 1 has historically received less research attention than Red 40 and Yellow 5, recent studies have raised important questions about its effects on the nervous system and gut microbiome.

Neurobehavioral Effects

The California Office of Environmental Health Hazard Assessment (OEHHA) included Blue 1 in its comprehensive assessment of synthetic food dyes and neurobehavioral effects in children.^[6] Animal research has linked Blue 1 to developmental delays and inhibition of nerve cell function. While the evidence base is less extensive than for Red 40 or Yellow 5, these findings suggest potential neurological concerns warrant further investigation.

A 2021 comprehensive review surveying natural versus synthetic blue dyes found that synthetic blue dyes like Blue No. 1 and Blue No. 2 may have toxic effects including potential neurotoxicity and carcinogenicity.^[7] The authors specifically contrasted these concerns with natural blue alternatives, which offer health benefits including antioxidant, anti-inflammatory, and neuroprotective properties. They concluded that synthetic blue food colorants should be replaced with natural alternatives due to safety concerns.

Gut Microbiome Effects

Emerging research on Blue 1 has focused increasingly on its effects on the gut microbiome—the community of microorganisms living in the digestive tract that plays crucial roles in health, immunity, and even mental function through the gut-brain axis.

A 2025 peer-reviewed paper reported lasting shifts in gut microbiota structure and function after Blue 1 exposure in an experimental model.^[8] While this represents emerging research rather than settled human harm, it adds to growing evidence that synthetic dyes may interact with gut bacteria in ways that could have downstream health implications.

The gut microbiome connection is particularly significant because gut bacteria are known to metabolize many substances, including food additives. Changes to microbiome composition and function could theoretically affect nutrient absorption, immune function, inflammation levels, and even mood and behavior through gut-brain signaling pathways.

Absorption and Distribution

One area of ongoing investigation involves how Blue 1 is absorbed and distributed in the body. While the dye is generally considered poorly absorbed from the intact gastrointestinal tract, there are circumstances where absorption may increase—including when the gut barrier is compromised, as may occur with inflammation or certain medical conditions.

Case reports have documented Blue discoloration of urine and skin in critically ill patients fed with tube feeding formulas containing Blue 1, suggesting that under certain conditions the dye can cross into systemic circulation.^[9] While these represent extreme cases, they demonstrate that absorption assumptions based on healthy individuals may not apply universally.

Important Caveats

The research on Blue 1 is less extensive than for some other synthetic dyes, partly because it was excluded from the Southampton Study that drove much EU regulatory attention. Much of the evidence comes from animal studies or in vitro research. The 2025 microbiome findings, while notable, represent emerging science that requires further investigation. Individual responses may vary, and effects at typical dietary exposures in healthy humans remain under study.

Nevertheless, the pattern of findings suggesting neurotoxicity potential, carcinogenicity concerns, and microbiome effects has led to Blue 1's inclusion in the FDA's phase-out initiative alongside other synthetic dyes.

Natural Alternatives to Blue 1

Creating natural blue color has historically been one of the more challenging tasks in food formulation, as truly blue pigments are rare in nature. However, several effective alternatives now exist:

Spirulina extract (Phycocyanin): Derived from blue-green algae, spirulina extract produces a vibrant blue color and offers health benefits including protein, vitamins, and antioxidants.^[6]It has become increasingly popular as a natural Blue 1 replacement, though it is sensitive to heat and highly acidic conditions.
Butterfly pea flower (Clitoria ternatea): This Southeast Asian flower produces a striking blue that changes color based on pH—blue in neutral conditions, purple when acidified with citrus. It has been used for centuries in traditional cuisines and is now appearing in Western products as a natural colorant.
Galdieria extract: Derived from a red algae species, this newer natural blue colorant offers good heat stability and has been gaining regulatory approvals for food use.
Red cabbage anthocyanins (pH-adjusted): While red cabbage naturally produces purple pigments, careful pH adjustment can shift these anthocyanins toward blue hues. This approach provides antioxidant benefits along with coloring.
Huito fruit (Genipa americana): This South American fruit produces a blue-gray to blue-black color and has been used traditionally for body painting and food coloring in indigenous cultures.

The 2021 review on blue dyes specifically noted that natural alternatives like anthocyanins and genipin offer health benefits including antioxidant, anti-inflammatory, anticancer, and neuroprotective properties—a stark contrast to the safety concerns associated with synthetic options.^[6]

How to Identify and Avoid Blue 1

To minimize exposure to Blue 1:

Check ingredient labels for: "Blue 1," "FD&C Blue No. 1," "Brilliant Blue," "Brilliant Blue FCF," "E133," or "CI 42090."
Look beyond blue products: Remember that Blue 1 is used to create green colors in combination with yellow dyes. Check green-colored products including mint items, lime-flavored foods, and some pickles.
Check beverages carefully: Sports drinks, energy drinks, and flavored beverages are common sources of Blue 1.
Review oral care products: Blue 1 appears in many mouthwashes and toothpastes. Look for dye-free alternatives.
Examine children's vitamins: Gummy vitamins often contain Blue 1 for color. Dye-free vitamin options are available.

The Bottom Line

Blue 1 (Brilliant Blue FCF) is the dominant synthetic blue colorant in the U.S. food supply, found not only in obviously blue products but also in many green-colored items where it's combined with yellow dyes. Like other FD&C colors, it is derived from petroleum and serves a purely cosmetic function—enhancing appearance without providing nutritional value.

While Blue 1 has received less research attention than some synthetic dyes, emerging studies raise concerns about neurotoxicity, carcinogenicity potential, and gut microbiome effects. A 2021 comprehensive review specifically concluded that synthetic blue dyes should be replaced with natural alternatives due to safety concerns—alternatives that offer health benefits rather than risks.

The FDA's inclusion of Blue 1 in its voluntary phase-out initiative signals regulatory recognition that even this historically "less scrutinized" dye warrants removal from the food supply. Consumers seeking to avoid Blue 1 now have viable natural alternatives including spirulina extract, butterfly pea flower, and other plant-derived colorants that can achieve similar hues while offering potential health benefits rather than risks.