Synthetic food dyes are getting a lot more scrutiny. Federal regulators, state lawmakers and food companies have all taken steps toward reducing or removing some of the bright colors used in candy, drinks, cereals and other packaged foods.
But that does not mean scientists have concluded that all synthetic food dyes are broadly harmful.
A JAMA Health Forum Viewpoint examines what researchers actually know about the health effects of synthetic dyes and how that evidence compares with the growing push to remove them from the food supply. The authors find that concerns about behavioral effects in some children have more scientific support than claims about cancer risk in people.
That distinction can get lost when food dyes are discussed as a single health threat.
For cancer, the evidence remains uncertain.
Much of the concern comes from animal and laboratory research rather than studies showing higher cancer rates among people who consume synthetic dyes. Red No. 3, for example, caused thyroid tumors in male rats at high doses through a biological process that may not apply to humans. Laboratory studies have also raised questions about inflammation and DNA damage from other dyes, including Red 40.
So far, however, researchers do not have strong human evidence showing that commonly used synthetic food dyes increase cancer risk.
The picture is different when it comes to children's behavior.
Randomized studies have found changes in hyperactivity and other behavioral measures after some children consumed synthetic dyes or removed them from their diets. The viewpoint also points to a California-commissioned review that found evidence of adverse behavioral effects in many of the challenge studies it examined.
The effects do not appear to be the same for every child.
Researchers still cannot reliably predict who may be sensitive to synthetic dyes. Studies have included children with attention disorders as well as children without them, and the size of the effects has varied.
Some estimates suggest that a relatively small share of children with attention-deficit/hyperactivity disorder may experience symptoms related to synthetic dyes.
That does not mean synthetic dyes cause ADHD. It also does not mean removing them will noticeably change behavior for most children.
Instead, the authors argue that the evidence is strong enough to justify a cautious approach, particularly because it remains difficult to identify which children might be affected.
That thinking is increasingly influencing food policy.
The FDA announced plans in 2025 to work toward removing petroleum-based synthetic dyes from the U.S. food supply, while several states have pursued their own restrictions. As of May 2026, however, Red No. 3 was the only synthetic dye whose federal authorization had been formally revoked.
Broader efforts have relied in part on voluntary commitments from food manufacturers, meaning synthetic dyes have not simply been banned across the board.
Replacing them can also be more complicated than changing one ingredient for another. Naturally derived colors may cost more, behave differently during manufacturing or storage and produce colors that look different from what consumers expect.
And removing a synthetic dye does not necessarily make the rest of a food nutritionally different.
Many brightly colored packaged foods also contain added sugars, sodium or refined carbohydrates. Those characteristics have much clearer implications for cardiometabolic health than the presence of a synthetic color alone.
That is especially important as concerns about food additives become wrapped into broader debates over ultraprocessed foods. The presence of a synthetic dye may be one characteristic of a packaged food, but it should not automatically be treated as the defining measure of whether that food is healthy or unhealthy.
For parents concerned about behavior, the authors recommend limiting children's exposure to certain synthetic dyes, including Yellow No. 5, Red No. 3 and Red 40. At the same time, they describe the overall health risk from synthetic dyes for the general population as modest compared with other dietary factors.
Taken together, the evidence lands somewhere between two common messages.
There is not strong evidence that synthetic food dyes broadly cause cancer or major health problems in people. But there is credible evidence that certain dyes may affect behavior in some children, even though researchers still cannot say exactly who is most likely to be sensitive.
The growing move away from synthetic dyes therefore reflects a mix of scientific evidence and precaution rather than proof that every dye has been shown to be harmful.
The published viewpoint does not list specific funding or support.