Red 40, also known as Allura Red AC, is a synthetic dye made from petroleum-derived chemicals. It is not extracted from any fruit, vegetable, or natural source. The raw materials come from naphthalene and other aromatic hydrocarbons found in crude oil, which are then transformed through a series of chemical reactions into the bright red powder used in thousands of food products.
The Chemical Building Blocks
Red 40 belongs to a class of chemicals called azo dyes, named for the nitrogen-to-nitrogen bond at the center of the molecule that gives it color. To build this molecule, manufacturers start with two petroleum-derived compounds and chemically join them together. One side of the molecule comes from a modified form of sulfanilic acid (a compound built from benzene, a basic petroleum building block). The other side comes from a naphthalene-based compound called 2-naphthol-6-sodium sulfonate.
The reaction that links these two halves is called azo coupling. First, one of the starting materials is treated with nitrous acid to create a reactive intermediate. That intermediate is then mixed with the naphthol compound, and the two snap together to form the finished dye molecule. This basic method was patented in 1970 by chemists at Allied Chemical and, according to the American Chemical Society, is still in use today. The final product is typically sold as a dark red powder or granule that dissolves easily in water.
Why Petroleum, Not Plants?
Synthetic dyes like Red 40 replaced natural colorings in the mid-20th century because they are cheaper to produce, more consistent in color, and far more stable. A natural red pigment from beets or berries can fade under heat, light, or acidic conditions. Red 40 holds its color through baking, boiling, and months of shelf life. It also produces a vivid, uniform red at very small concentrations, which keeps production costs low for food manufacturers.
The tradeoff is that the dye has no nutritional value whatsoever. It exists purely for appearance. You’ll find it in candy, cereals, snack chips, sports drinks, flavored yogurts, salad dressings, and even some medications. Red 40 is the most widely used artificial food dye in the United States, accounting for roughly 40% of all dye consumption in the food supply.
Health Concerns and the Hyperactivity Link
The biggest question around Red 40 isn’t what it’s made of but whether those petroleum-derived ingredients pose any risk once you eat them. Most of the concern centers on children’s behavior. A widely cited 2007 study published in The Lancet tested two different mixtures of artificial food colors (including Red 40) and a preservative on 153 three-year-olds and 144 eight- and nine-year-olds. Researchers measured hyperactivity using a combination of parent ratings, teacher ratings, and computerized attention tests.
The results showed small but statistically significant increases in hyperactive behavior compared to placebo. Among the younger children, one of the dye mixtures produced a measurable effect, and the effect grew larger when the analysis focused on children who consumed at least 85% of the test drinks. Among the older children, both dye mixtures increased hyperactivity scores. The study concluded that artificial colors, a sodium benzoate preservative, or both increased hyperactivity in children from the general population, not just in children already diagnosed with attention disorders.
The effect sizes were modest. This means the average child showed only a slight behavioral shift, not a dramatic transformation. But for some children, particularly those who may already be sensitive, the effect could be more noticeable. This study became the basis for regulatory action in Europe.
How Different Countries Handle Red 40
Red 40 is not banned in the European Union, but it comes with strings attached. Any food or drink sold in the EU that contains Allura Red (listed as E129) must carry a mandatory warning label stating: “May have an adverse effect on activity and attention in children.” Five other synthetic dyes carry the same requirement. That warning has pushed many European food companies to voluntarily reformulate their products with natural colorings instead, which is why the same brand of candy or cereal often looks different in Europe than it does in the United States.
In the U.S., the FDA historically maintained that Red 40 is safe at approved levels. That position shifted significantly in April 2025, when the FDA announced a national initiative to phase out petroleum-based food dyes from the American food supply. The agency is working with food manufacturers and retailers to eliminate Red 40 and five other certified color additives by the end of 2027. This marks the first time the U.S. government has moved to remove these dyes rather than simply defending their safety.
What This Means for Your Food
If you want to avoid Red 40 now, check ingredient labels for “Red 40,” “Allura Red,” “FD&C Red No. 40,” or “E129.” It shows up in products you might not expect, including white-frosted cakes (used in tiny amounts to brighten the white), brown-colored sauces, and orange-colored snacks where it’s blended with yellow dyes.
Products colored with alternatives will typically list ingredients like beet juice concentrate, paprika extract, or annatto. These natural options can behave differently in recipes and may shift color slightly over time, but they avoid the petroleum-derived chemistry entirely. As more manufacturers reformulate ahead of the 2027 target, these natural alternatives are becoming increasingly common on U.S. shelves.