Caramel color is the brown food dye that gives colas and other dark sodas their familiar appearance. It’s made by heating sugars like glucose, fructose, or sucrose at high temperatures with various chemical reactants, producing a deep brown liquid that has no meaningful flavor at the concentrations used in beverages. It is the single most widely used food coloring in the world by weight, and almost every dark-colored soda on the market contains it.
How Caramel Color Is Made
Despite the name, caramel color has little in common with the caramel you’d drizzle on ice cream. It starts with the same raw materials, primarily corn-derived glucose syrup, sucrose, or fructose, but the manufacturing process pushes far beyond simple caramelization. The sugars are heated under controlled conditions with specific chemical compounds that determine the final product’s properties.
There are four distinct classes of caramel color, each defined by the reactants used during production:
- Class I (plain caramel): Sugars heated with an acid or alkali. The simplest version, sometimes called spirit caramel.
- Class II (caustic sulfite caramel): Sugars heated with sulfite-containing compounds.
- Class III (ammonia caramel): Sugars heated with ammonium compounds. Common in beer and baked goods.
- Class IV (sulfite ammonia caramel): Sugars heated with both ammonium and sulfite compounds. This is the type used in virtually all colas and dark sodas.
Class IV is the go-to for soft drinks because it’s stable in acidic, carbonated liquids and carries a strong, consistent brown color at low concentrations. Its industry nickname is literally “beverage caramel” or “soft-drink caramel.”
Why Class IV Raises Health Questions
When sugars react with ammonia and sulfite compounds at high temperatures, the process creates a byproduct called 4-methylimidazole, commonly shortened to 4-MEI. This chemical has no function in the final product. It’s simply a contaminant that forms during manufacturing, and its presence in widely consumed beverages has drawn scrutiny from toxicologists and regulators.
A two-year feeding study by the National Toxicology Program found clear evidence that 4-MEI caused lung tumors in mice. In both male and female mice, the rates of lung adenomas and carcinomas increased significantly with higher doses. Among male mice at the highest exposure level, combined lung tumor rates reached 22 out of 50 animals, compared to 9 out of 50 in the control group. In rats, the evidence was weaker: female rats showed a borderline increase in leukemia, while male rats showed no carcinogenic response at all.
These were high-dose animal studies, and the amounts of 4-MEI the animals consumed were far greater than what a person would get from drinking soda. Still, the findings were enough to put 4-MEI on California’s Proposition 65 list of chemicals known to cause cancer. After that listing, major soda manufacturers reformulated their caramel color to reduce 4-MEI levels rather than put warning labels on their products sold in California.
Potential Metabolic Effects
Beyond cancer risk, newer research has looked at what chronic 4-MEI exposure does to metabolism. In one study, mice given 4-MEI daily for seven weeks developed abnormally low blood sugar and abnormally high insulin levels. The cause appeared to be overgrowth of the insulin-producing cells in the pancreas, essentially pushing the animals into a state of constant insulin overproduction. The mice also showed signs of increased fat production and liver damage, measured by elevated markers of oxidative stress in liver tissue.
A human component of that same research found that people who regularly consumed beverages containing 4-MEI had higher levels of C-peptide (a marker of insulin production), along with elevated LDL cholesterol and triglycerides, compared to people who didn’t consume those beverages. Their blood sugar was also lower. These findings are preliminary and don’t prove that caramel color alone drives metabolic problems, especially since people drinking large amounts of cola typically have other dietary patterns that affect metabolic health. But they suggest 4-MEI may have biological effects beyond cancer risk that deserve attention.
How It’s Regulated
The FDA classifies caramel color as a color additive exempt from certification, meaning it doesn’t undergo the batch-by-batch testing required for synthetic dyes like Red 40 or Blue 1. On ingredient labels, manufacturers are only required to list it as “caramel color.” They don’t have to specify which of the four classes they used, and they don’t have to disclose 4-MEI levels. So when you see “caramel color” on a soda can, you have no way to know from the label alone whether it’s the simpler Class I or the 4-MEI-producing Class IV, though in cola it’s almost certainly Class IV.
In Europe, the four classes are labeled separately as E 150a through E 150d, giving consumers slightly more information. The European Food Safety Authority set a group acceptable daily intake of 300 mg per kilogram of body weight per day for caramel colors overall, with a lower individual limit of 100 mg/kg/day for Class III due to concerns about a compound called THI that may affect the immune system. Notably, EFSA’s own analysis concluded that children and adults in Europe may exceed the acceptable daily intake for Classes I, III, and IV based on typical consumption patterns.
California’s Proposition 65 takes a different approach, focusing specifically on 4-MEI exposure rather than the caramel color itself. Businesses selling products in California must provide a cancer warning if their products expose consumers to significant levels of 4-MEI. The major cola brands responded by working with their caramel color suppliers to develop lower-4-MEI formulations, which are now used in products sold across the United States, not just in California.
What Caramel Color Actually Contributes to Your Soda
Caramel color is purely cosmetic. It doesn’t sweeten the drink, preserve it, or change the flavor in any detectable way at the concentrations used. A clear cola would taste the same. The brown color exists because consumers associate it with cola flavor, and an amber or clear version of the same drink tends to perform poorly in taste tests, not because it tastes different, but because color shapes perception of flavor.
Some smaller beverage brands have moved away from caramel color entirely, marketing clear or naturally tinted alternatives. The options for natural brown coloring in acidic beverages are limited, though. Ingredients like barley malt syrup or fruit juice concentrates can provide some color, but none match the intensity, stability, and cost-effectiveness of Class IV caramel color in a carbonated, acidic environment. For the foreseeable future, if you’re drinking a mainstream cola, you’re drinking Class IV caramel color.
Putting the Risk in Perspective
The 4-MEI levels in modern sodas are substantially lower than what they were before 2012, when California’s Prop 65 listing forced reformulation. The doses used in the mouse studies that showed clear carcinogenic effects were also orders of magnitude higher than what a person would consume, even drinking several cans of cola a day. No human study has directly linked caramel color consumption to cancer.
That said, caramel color is a purely cosmetic additive with no nutritional value, and it introduces a chemical contaminant that wouldn’t otherwise be in your diet. For people who drink soda occasionally, the 4-MEI exposure is negligible. For heavy daily consumers, the exposure adds up, and the metabolic findings around insulin and cholesterol, while early, suggest the byproducts of caramel color production may interact with the body in ways that go beyond simple coloring.