What We Know about Artificial Food Dyes and Health as RFK, Jr., Declares a U.S. Ban

Scientific American

22-04-2025

On Tuesday Robert F. Kennedy, Jr., announced plans to order the U.S. food industry to eliminate eight petroleum-based food dyes within the next two years, based on some evidence that links them to health risks.
The move by Kennedy, the Trump administration's secretary of the Department of Health and Human Services, follows his earlier promises to ban various chemical food additives—including artificial colorings that are commonly used to brighten rainbow-colored cereals, pastries, chips, candies and other processed foods. Individual states, such as California and West Virginia, have also independently pushed legislation to ban certain food dyes and preservatives this year. At today's press event, Kennedy discussed the directive and various claims about the nutritional value of foods alongside Food and Drug Administration director Marty Makary, National Institutes of Health director Jay Bhattacharya and other public officials. Makary said they will establish a timeline for the food industry transition to 'natural alternatives.'
'There's no reason not to remove [such artificial food dyes] if they're there just for visual appeal. If there's no health-promoting purpose, and there's actually even the slightest risk of detriments to health, then why not remove them?' says Kathleen Melanson, a nutritional scientist at the University of Rhode Island. She adds, however, that these chemical dyes are likely only part of the problem. 'There's so much more to food than single factors,' Melanson says.
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What It Means
The FDA currently certifies nine color additives for use in foods. By this past January the outgoing Biden administration had already started the process to ban one of them, Red No. 3. Kennedy will target the other eight artificial food dyes, such as Yellow No. 5, Blue No. 1 and Red No. 40.
The decision to ban Red No. 3 was based on a study in which male rats developed thyroid tumors after being exposed to high levels of the substance. Even though other studies in humans and animals failed to show similar results, the dye was banned under the Federal Food, Drug and Cosmetics Act's Delaney Clause, explains Tracy Crane, an associate professor of medical oncology at the Sylvester Comprehensive Cancer Center, part of the University of Miami Miller School of Medicine and the University of Miami Health System.
'In the Delaney Clause, [proponents of the ban] were able to state that anything that caused cancer in humans or animals could be eliminated from the diet, and that's what happened with Red No. 3,' says Crane, who had wondered if other food dyes would experience the same fate. 'There are definitely studies for some of these [dyes] that are on the list that have shown cancer-causing properties in mice.'
What the Evidence Says
Older animal studies have associated some blue, yellow and red dyes with risks of tumor development and neurotoxicity. Some research suggests the neurotoxicity may contribute to attention deficit hyperactivity disorder. Melanson calls the evidence 'mixed,' however. Direct exposure has only been tested in animals. Human data have been mostly limited to population or epidemiological studies—in which participants have been asked to recall and self-report the foods they've eaten. This has led some scientists to say there is not enough information to make conclusions about food dyes' potential health threats.
An FDA research review on food dyes' potential effects on children's behavior also concluded that most children didn't experience adverse effects, though some individuals may be sensitive to some dyes. The FDA states that color additives are safe to consume when they are used according to the agency's regulations. And the International Association of Color Manufacturers, a group representing the global color industry, has previously said that the small levels of artificial food dyes that humans typically eat are generally safe. (At press time, the association has not responded to a request for comment from Scientific American.)
'The danger is always in the dose,' Melanson says.
A Wall Street Journal analysis evaluated U.S. Department of Agriculture data for more than 450,000 food products and found that 10 percent contained at least one artificial dye—and that more than 40 percent had multiple dyes. 'When food additives are approved, they're generally tested one at a time,' Melanson says. 'We don't know what happens with interactions.'
Consuming a food with multiple dyes makes it difficult to know the total dose that has been ingested, Melanson says. The accumulative effects of a whole diet comprised of many different foods with artificial dyes, consumed over a lifetime, is even harder to assess. A disease like cancer takes a long time develop, Crane says, noting, 'It's very hard for us to really know what the direct impact of these food diets is.' She adds that not all the dyes are made the same and each may be processed in the body differently.
Melanson and Crane agree that food dyes are just one ingredient that may contribute to health risks.
'It's not just about one type of ingredients; it's about every ingredient that's in there,' Melanson says. 'If it's all tunnel vision on one factor without considering these other potential risk factors—the excess of sodium and sugar and processing, lack of fiber, lack of fortifying nutrients—then we might be missing some aspects.'
More details are pending, but it's expected that food manufacturers may have to alter their production practices or consider alternative coloring additives. Natural, food-based sources such as turmeric, paprika, pumpkin or carrot have been used as well. But it's unclear what the transition will cost manufacturers and federal agencies, Melanson says. Currently, manufacturers have until 2027 to remove Red No. 3 from food products and until 2028 to remove it from medicines. At today's press briefing, however, RFK, Jr., and other health officials asserted that this dye and the others need to be removed sooner, though no official timeline was presented.
'I know these procedures take time, and food manufacturers have to reformulate,' Melanson says. 'But in the meantime, Americans can consider backing off ultraprocessed foods—the ones that are obviously at the high end of the spectrum of processing and formulation.'