Blue 2 Lake is an insoluble pigment used to add blue color to foods, medications, and cosmetics. It’s made by chemically bonding the water-soluble dye FD&C Blue No. 2 (also called Indigo Carmine) onto an aluminum salt base, creating a stable powder that won’t dissolve in water. You’ll find it listed on ingredient labels for candy coatings, tablets, chewing gum, and many other products where a consistent blue color needs to stay put.
How Blue 2 Lake Differs From Blue 2 Dye
FD&C Blue No. 2 exists in two forms, and the distinction matters for how it behaves in food. The straight dye dissolves in water and works well for coloring liquids like beverages or gelatin. The lake version is insoluble. It doesn’t dissolve in water or oil but can be dispersed (mixed evenly) into fats, oils, sugar solutions, and glycerin. Think of the difference like watercolor paint versus a colored powder you stir into frosting.
This insolubility gives lakes a practical advantage: they don’t bleed. In products with multiple colors sitting next to each other, like layered candies or coated tablets, a water-soluble dye would migrate from one section to another. Lakes stay where you put them. That’s why they’re the go-to choice for chocolate coatings, hard candy shells, pill coatings, and cosmetics where color precision matters.
What It’s Made Of
The FDA registers Blue 2 Lake under the chemical name “FD&C Blue No. 2, Aluminum Lake” with CAS registry number 16521-38-3. The process starts with the water-soluble dye Indigo Carmine, which is then chemically reacted with an aluminum-based substrate. The dye molecules bond to the aluminum hydroxide, producing an insoluble pigment particle. The result is a fine powder that provides color through dispersion rather than dissolution.
The FDA formally defines lakes as “insoluble pigments formed by chemically reacting water-soluble straight colors with precipitants and substrata.” Most lakes, including Blue 2, are provisionally listed for use in food, drugs, and cosmetics under federal regulations.
Where You’ll Find It
Blue 2 Lake shows up in a wide range of products. In food, it’s common in chocolate coatings, candy shells, frosting, and baked goods where a fat-based or dry environment makes water-soluble dyes impractical. Pharmaceutical companies use it to color the outer coating of tablets and capsules. It also appears in cosmetics like eyeshadow, blush, and lip products, where its stability and resistance to bleeding make it more reliable than a dissolved dye.
The hard-panning technique used for coating gum balls and sugar-shelled candies relies on lakes dispersed in a sugar and water solution. If you’ve ever noticed that M&M’s or similar coated candies have sharp, distinct color boundaries without smudging, that’s the lake form at work.
Safety Profile and Controversy
Blue 2 Lake is FDA-approved, but its safety isn’t without debate. The European Food Safety Authority set an acceptable daily intake of 5 mg per kilogram of body weight per day for Indigo Carmine (the dye behind Blue 2 Lake), though the agency noted that this limit was based on studies using a specific high-purity formulation and might not apply to lower-purity versions.
A long-term study in rats fed Blue 2 at dietary levels up to 2% for 30 months found a statistically significant increase in brain tumors (gliomas) in high-dose males. However, researchers concluded this increase was not biologically significant because the overall brain tumor rate fell within the normal range for that strain of rat at that age, and the finding didn’t meet established criteria for classifying a substance as a brain carcinogen.
The Behavioral Effects Debate
The bigger concern in recent years has centered on whether synthetic food dyes, as a class, affect children’s behavior. A comprehensive assessment by California’s Office of Environmental Health Hazard Assessment reviewed Blue 2 alongside six other FDA-certified dyes and concluded that synthetic food dyes are associated with inattentiveness, hyperactivity, and restlessness in sensitive children. The effects were observed in children both with and without pre-existing behavioral disorders.
The assessment drew on multiple evidence streams: human studies, animal neurotoxicology, and mechanistic research. Multiple meta-analyses combining results from several studies supported a link between food dye exposure and adverse behavioral outcomes in children. The report also raised the concern that current FDA safety thresholds may not adequately protect children from neurobehavioral impacts, since the original safety limits were set using older studies that didn’t focus on these effects.
It’s worth noting that not all studies found behavioral effects, and sensitivity varies from child to child. But the Center for Science in the Public Interest, a consumer advocacy group, rates all seven major synthetic dyes, including Blue 2, as “Avoid” in its Chemical Cuisine database, citing the neurobehavioral evidence.
How to Identify It on Labels
On U.S. food labels, you’ll see it listed as “Blue 2 Lake” or “FD&C Blue No. 2 Aluminum Lake.” In European products, the equivalent dye is labeled E 132, though the lake form may be specified separately. Cosmetic labels sometimes use the Color Index designation C.I. 73015. If you’re scanning ingredient lists to avoid synthetic dyes, any of these names refers to the same substance.