Your M&Ms are changing colors. But are the new natural dyes safe?

M&M’s, Skittles, Starburst and EXTRA gum are set to undergo an “au naturel” makeover this month. 

Mars is rolling out new versions of its best-known confections that no longer include synthetic food dyes, “the colors that have a number behind them,” said Thomas Galligan, principal scientist for food additives and supplements at the Center for Science in the Public Interest. “Red 40, Yellow 5, Yellow 6, the big ones. There’s also Blue 1, Blue 2, Green 3 and also Red 3.” 

Mars is the latest major food company to shift away from synthetic dyes; the new candies will be available on Amazon by the end of August, according to a company press release. Earlier this month, WK Kellogg announced it would remove them from its cereals — including Froot Loops and Apple Jacks — by the end of 2026. General Mills eliminated the dyes from products it sells to K-12 schools and pledged to remove them from all its U.S. cereals by this summer as well as its entire U.S. retail portfolio by the end of 2027. Kraft Heinz pledged to remove all remaining synthetic colors from its U.S. products by the end of 2027.

The industry-wide change follows Health and Human Services Secretary Robert F. Kennedy Jr.’s push to rid the American food supply of petroleum-based dyes, a cornerstone of his Make America Healthy Again agenda. In April 2025, he and the Food and Drug Administration announced plans to phase out six widely used synthetic dyes, largely through voluntary commitments from food manufacturers rather than outright bans.

For decades, mounting scientific evidence has linked synthetic food dyes to behavioral problems in some children, including increased inattention, restlessness and irritability. Yet the FDA has continued to allow most of the dyes in American foods. While environmental health experts have welcomed the Trump administration’s push to reduce exposure, some argue its voluntary approach doesn’t go far enough. And as manufacturers swap synthetic dyes for colors derived from plants, algae and other natural sources, a new question has emerged: Are the alternatives any safer? 

A brief history of food dyes

Humans have been coloring their food for thousands of years. Ancient civilizations used pigments derived from plants and minerals — including paprika, saffron and iron — to color food and wine as early as 300 B.C.

British chemist William Henry Perkin sparked the modern food dye revolution in 1856 when he accidentally discovered the first manmade dye, a purple hue known as mauve, while trying to develop a malaria treatment. Similar colors, mostly derived from coal tar — the thick black liquid produced when coal is heated in the absence of oxygen — quickly followed and eventually made their way into foods, medicines and cosmetics.

While most original synthetic dyes came from the byproducts of coal processing, today’s dyes are made by taking chemicals derived from petroleum and transforming them through a series of chemical reactions into colors like Red 40 and Yellow 5.

By 1900, artificially colored foods were commonplace in the U.S. Some were dangerous. Manufacturers used substances containing lead, arsenic and mercury — metals linked to neurological and organ damage, developmental problems and, in the case of arsenic, cancer. In other cases, dyes were added to disguise spoiled or poor-quality products.

The federal government stepped in to regulate food coloring practices in 1906 when it passed the Food and Drugs Act, prohibiting poisonous or harmful colors and barring companies from using coloring to conceal damaged or inferior food. By 1931, the federal government had approved 15 artificial food dyes.

The FDA clamped down on color additives at least twice. In 1950, the agency reevaluated the colors on the market and removed several after children became sick from eating Halloween candy containing an approved orange dye. A decade later, Congress passed the Color Additive Amendments, which established much of the modern regulatory framework and required manufacturers to prove color additives were safe for their intended use. In the following years, the FDA removed additional dyes as new safety concerns emerged, leaving only a handful in widespread use today.

But Galligan and other scientists argue that the FDA’s safety determinations for the remaining dyes haven’t kept pace with the science.

“The FDA’s approvals that still exist today are based on decades-old animal studies that were not designed to assess behavioral effects,” Galligan said. “It’s really the human studies that are the most important to consider here, and when the FDA did look at the human studies, they did so in a very limited way.”

The science on synthetic food dyes

For more than 50 years, researchers around the world have raised concerns about the potential health effects of synthetic food dyes. Much of the evidence points to changes in children’s behavior. 

In 2021, California’s Office of Environmental Health Hazard Assessment, or OEHHA, undertook one of the most comprehensive reviews of the evidence. At the direction of the state legislature, the agency reviewed 27 clinical trials in children, dozens of studies in animals and additional laboratory research examining how artificial dyes might affect brain function and behavior.

“What we did find is that there is evidence that food dyes can exacerbate symptoms like restlessness, irritability, inattention and sleep disturbances,” said Cyrus Rangan, director of OEHHA’s Children’s Environmental Health Center. “Those kinds of things can be made worse in children when they are exposed to food dyes.” 

Galligan said the combination of human clinical trials, animal research and laboratory studies makes the evidence particularly compelling. 

“Scientists, especially state scientists, don’t use the word ‘cause’” lightly, he said. California researchers concluded, “that in fact there is a causal relationship between food dyes and adverse behavioral outcomes in some children.”

Animal and laboratory studies also offer clues about how dyes might trigger those behavioral changes. Rangan said some dyes appear to interfere with systems that regulate dopamine and histamine, chemicals in the brain that, respectively, control reward, motivation and movement and wakefulness, arousal and energy. 

Normally, the brain is “very good at what I like to call micromanaging the amounts of dopamine and histamine and other neurochemicals in our brain,” Rangan said. But studies suggest artificial food dyes disrupt that process, and “that can be partially responsible for the irritability, the restlessness, and all of those other problems,” he said. 

OEHHA’s assessment provides strong evidence that synthetic food dyes can affect behavior in some children. Scientists are also homing in on the biological mechanisms that could explain those changes. But the evidence is more nuanced than some of Kennedy’s statements about the harms of food dyes.

During a March 2025 appearance in West Virginia celebrating a new state law banning seven synthetic dyes, Kennedy linked the dyes not only to attention-deficit/hyperactivity disorder (ADHD) but to a much broader range of health problems. 

“The loneliness, the dispossession, the crisis that we have in mental health, in suicide, in [attention deficit disorder], ADHD, all of these are linked — and particularly to the dyes,” Kennedy said. “It’s very clear the dyes that Gov. Morrisey is banning, all of them are linked in very, very strong studies to ADHD and to cancers.” 

The OEHHA assessment did not reach conclusions that broad. Rangan stressed that consuming artificial food dyes does not cause a child to develop ADHD. 

“There’s no conclusive evidence right now that says synthetic food dyes cause ADHD or cause related disorders,” he said. “But what we can say is that children who already have some of these disorders, whether they’re diagnosed or undiagnosed, may see a worsening of those symptoms appearing as a result of exposure to food dyes. That’s the state of the science right now as we understand it.”

Other questions remain. Researchers aren’t sure precisely how much dye it takes to produce an effect nor can they predict which children will be affected. Some evidence suggests that higher doses lead to greater side effects, but Rangan said scientists still have significant questions about dose and duration of exposure. 

Outside of the behavioral effects in some children, Rangan said animal studies have linked blue dyes to cardiovascular problems, including changes in heart rate and blood pressure, while Red 3 has been associated with thyroid tumors in rats. But those findings don’t establish that the dyes cause the same effects in people; rather, Rangan said, animal studies can flag potential hazards that warrant further investigation.

Why hasn’t the FDA banned synthetic food dyes?

Despite the growing evidence around synthetic food dyes, the FDA has stopped short of outright banning petroleum-based colors, though it has recently taken some regulatory action. In January 2025, the agency revoked its authorization for Red 3 after studies found that high doses caused thyroid cancer in male rats. Food manufacturers have until January 2027 to remove it from products. Last month, the FDA revoked authorization for Orange B and proposed doing the same for Citrus Red No. 2, though both of those dyes are no longer used by industry.

But for Red 40, Yellow 5, Yellow 6, Blue 1, Blue 2 and Green 3, rather than rely on FDA regulation, the Trump administration has called on food manufacturers to voluntarily phase out artificial dyes by the end of 2026.

That’s not because the FDA lacks the authority to act, Galligan argues.

“The FDA is actively choosing not to use its regulatory authority here,” he said. “The FDA absolutely has the authority to come out and establish regulations to limit, ban, restrict these food dyes if it were so inclined.”

Galligan says there are likely two driving forces behind this approach. 

“The fact that the Trump administration is relying on voluntary phase out from industry, I think, is probably a reflection of the fact that the Trump administration broadly is deregulatory, anti-regulatory in its sort of framing. It doesn’t want to issue new regulations; it doesn’t want to really hold industry to regulatory accounts,” he said.

In addition, the FDA has historically been reluctant to revisit and overturn prior decisions and to conduct the kinds of comprehensive reviews like the one led by the state of California.

“There’s been a longstanding failure by the FDA to proactively assess the safety of chemicals that are in our food,” Galligan said. When new evidence suggests a chemical is harmful, he added, the agency allows it “to linger in our food supply long after we know that it’s harmful.”

The agency’s actions around Red 3 illustrate that lag. Studies completed as far back as the 1980s found that high doses of the dye caused thyroid tumors in male rats. In 1990, the FDA acknowledged those concerns but also said the mechanism behind the tumors does not occur in humans. Thirty-five years later, the agency revoked authorization for Red 3.

“FDA for a very long time has failed to really keep up with its obligations to ensure that the chemicals in our food are truly safe,” Galligan said.

Galligan said part of the problem is practical: Comprehensive safety reviews like OEHHA’s require scientists, time and money, and FDA’s food chemical programs have historically been underfunded. But he also points to what he describes as a cultural reluctance within the agency to reverse earlier decisions.

“The agency is reticent to go back on decisions it made previously,” he said. “At least that’s the impression that we have gotten, that the FDA is not willing to go back and say, ‘We got this wrong.’”

Are natural alternatives safer?

As food manufacturers move away from synthetic dyes, many are turning to colors derived from natural sources. Mars, for example, is using ingredients such as turmeric, beet juice and spirulina to create the familiar yellow, red and green colors in its new candies. 

But natural doesn’t necessarily mean safer.

“People might see natural versus artificial as sort of an indicator of what is safe and healthy, and that isn’t necessarily true,” Galligan said. “There are natural substances that are harmful, and so it’s important that we don’t just accept these natural colors on face value.”

Unlike synthetic dyes, which have been studied for decades, the evidence surrounding some of their natural replacements is much thinner. And lumping them together as “natural dyes” can be misleading; the category encompasses different substances derived from very different sources, each with their own potential risks.

“While you may be removing one problem, you may be adding another,” Rangan said. “There does need to be some rigorous research on those things as well to settle the science on alternatives, how safe they are and how much you can use in these various products.”

Some natural dyes have known risks. Carmine, a red color made from an insect called a cochineal, can cause serious allergic reactions in some people. The FDA requires companies to list carmine and cochineal extract by name on food labels. Other natural dye alternatives, however, simply don’t have the same depth of evidence available to assess whether long-term consumption poses any health risk.

That doesn’t mean natural dyes are dangerous. It means scientists don’t yet have enough evidence to assume that replacing a well-studied synthetic color with a plant- or algae-derived alternative necessarily makes a product safer.

Galligan argues that because food dyes provide no nutritional or food-safety benefit, the bar for demonstrating their safety should be especially high. 

“These natural colors, like the synthetic colors, are purely marketing tools for the food companies,” he said. 

Rangan noted that dyes aren’t always purely cosmetic: In medications, for example, different colors can help patients and caregivers distinguish between pills, potentially preventing medication errors. 

But by and large, “they’re not strictly necessary,” Galligan said. “They don’t offer any nutritional or food safety value to consumers. So we should hold them to a very, very high safety standard.”

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