Food Fight: A 50-Year Debate Over Food Dyes Reaches a Regulatory Turning Point in U.S.

For decades, scientists, regulators, parents, and consumer advocates have debated whether synthetic food dyes do more than simply make foods look appealing. Since the 1970s, researchers have investigated whether artificial color additives can affect children's behavior, particularly symptoms related to attention, impulsivity, and hyperactivity. The question has persisted through generations of studies, regulatory reviews, and public health campaigns, with evidence accumulating but consensus often remaining elusive.

At the center of the debate are studies spanning more than 30 years, including a landmark 1994 experiment conducted by researchers Katherine and Kenneth Rowe. Seeking to test whether synthetic food dyes could contribute to hyperactivity and other behavioral changes in children, the Rowes focused on Yellow 5, also known as tartrazine. Their findings would become one piece of a larger body of evidence that continues to influence policy discussions today.

The Rowes' theory stemmed from previous research showing that the Feingold diet, which called for avoiding artificial dyes among other food additives, had positive effects on the studied children's behavior. The 1994 test focused on one of the synthetic food dyes avoided by the diet, Yellow 5. The results seemed to back up what the Rowes had theorized. “Behavioral changes in irritability, restlessness, and sleep disturbance are associated with the ingestion of tartrazine in some children,” they wrote in their paper.

Today, that long-running scientific debate is no longer confined to academic journals. In 2025, lawmakers across the United States introduced and passed a growing number of measures aimed at restricting synthetic food dyes in schools and consumer products. Supporters, which include followers of the Make America Healthy Again (MAHA) movement, argue that decades of research justify a precautionary approach, while industry groups have pushed back, arguing that federal safety reviews continue to support the dyes' use.

The debate has put decades-old research, newer state-level health assessments, and questions about legislative authority at the center of a fast-moving policy fight. This article is the first in a series looking at the science behind synthetic food dyes, as well as how that science is being translated into state legislation.

OEHHA Health Assessment

In April 2021, the California Office of Environmental Health Hazard Assessment (OEHHA) released a health effects assessment titled “Potential Neurobehavioral Effects of Synthetic Food Dyes in Children.” The report took a broad look at widely used synthetic food dyes then narrowed in on the most relevant human and animal studies, especially those examining dose-response relationships. Dr. Cyrus Rangan, director of the Children’s Environmental Health Center at OEHHA sat down with 3E to go over the details of the assessment.

Rangan said key to the report was finding studies like the Rowes' that focused on single dyes. This was because the challenge in any research into the impact of food dyes is that children are rarely exposed to a single dye in isolation. Instead, they may consume different combinations of dyes through a range of foods and drinks, making it difficult to attribute a behavioral effect to any one additive. The Rowes' research into Yellow 5, therefore, is an important outlier.

“In particular, Yellow Dye No. 5 was one of the [dyes] that was most compelling,” said Rangan. “Basically, what they did is they took children, split them into groups, gave some children placebos, and other groups were given Yellow Dye No. 5 in incremental doses. And what they found is that there was an incremental effect on things like hyperactivity, as the doses of those dyes were increasing.”

Outside of human research, Rangan said that animal toxicology studies were also included in the report. Those studies allowed researchers to isolate specific dyes and examine possible biological mechanisms that may explain behavioral effects observed in children.

How Food Dyes Impact Children

What the research found, according to Rangan, is that synthetic food dyes may affect the central nervous system by interfering with neurotransmitter activity in the brain. One pathway that was of particular note involved dopamine.

“Food dyes can interfere with a particular protein in our brain. It's called DAT1,” said Rangan. “That is a regulator protein that helps regulate the reuptake or recycling of dopamine that gets released from our nerves.”

By interfering with the pathway, dyes may cause dopamine to “hang around longer than it is supposed to” between nerve cells, which can lead to an overstimulation of the nerves. That mechanism may help explain why some children appear more sensitive to dyes than others. According to Rangan, research suggests children already diagnosed with attention deficit disorder (ADD) or similar disorders may be more likely to show behavioral changes after dye exposure.

Rangan said the behavioral effects described in the literature are generally short term. In challenge studies, children exposed to dyes showed behavioral changes, then returned to baseline after exposure ended. However, he cautioned that a return to baseline in short-term studies does not prove there are no longer-lasting effects. The existing studies may not have been designed to detect subtle or persistent changes.

“It could be that there is lingering injury or lingering effects that we're not necessarily able to detect in these studies, because the studies just weren't comprehensive enough or long-term enough to actually look for them,” said Rangan.

Still, Rangan shared that parental reports showed promising results. Some parents involved in studies reported noticeable improvements after children followed dye-free diets for several weeks.

“This is something that [other clinicians] approach me as a toxicologist saying, 'I see this food dye-free diet, and I have a mom who's interested in it. Is that something that's real?'” he said. “And I replied, 'Yeah, a lot of parents have reported that they see real differences.'”

Overall, Rangan framed the 2021 report as an assessment of converging evidence: human challenge studies, animal toxicology, and mechanistic research that together suggest synthetic food dyes can affect neurobehavior in some children. The evidence, they said, does not show that every child is affected in the same way, but it does suggest that some children may be more vulnerable to behavioral effects from synthetic dye exposure, particularly where attention or hyperactivity-related symptoms are already present.

Future of Food Dye Research and Regulations

While Rangan stressed that existing evidence is strong enough to show that there are negative impacts from food dyes that need to be addressed, they shared that several gaps remain in the scientific record. Much of the existing evidence, they said, looks at short-term behavioral changes after children are exposed to dyes, leaving unanswered questions about whether repeated or early life exposures could have more persistent effects.

“What we would like to see is, whether it comes from researchers or from industry or whoever is looking at this, more [research] on mixtures, more [research] on the long-term impacts,” said Rangan. “And more on in utero exposure.”

Rangan also said that more research is needed on natural dyes, which food manufacturers may use as substitutes for synthetic colorants. Natural dyes often must be used in larger amounts than synthetic dyes to achieve similar colors, creating additional questions about exposure and health impacts.

“Just because something is natural doesn't necessarily mean it's safe,” he pointed out.

While the research is ongoing, the current data is being used to move ahead with regulating food dyes. California has enacted two major laws restricting food dyes; one banning them from public K-12 schools and another banning Red Dye No. 3 from foods sold in the state. Rangan added that the California laws are reaching past state boundaries.

“We are very gratified to see that, because of this work, other states are starting to look at [food dyes],” said Rangan. “And the federal government is starting to look at this too.”

Still, more can be done. Rangan highlighted that schools are a logical place for policymakers to focus because they are a centralized point of exposure to food additives for children, from cafeteria foods and lunches brought from home to vending machines. He also pointed to the precautionary principle as a basis for action, particularly when children are the exposed population. He said regulators often seek causal proof before imposing sweeping bans, but associations identified in scientific assessments can support regulatory action.

There's enough information in the food dye report to allow researchers and regulators to say, “Hey, we need to take a comprehensive approach. We need to take a precautionary approach to all of this,” said Rangan.

Overall, while the research does not suggest that every child will respond the same way to synthetic dyes, the findings highlighted by the OEHHA have given policymakers a scientific basis to act without waiting for every question to be answered.

The next article in this series will look at a specific case in West Virginia that shows how effective these policies can be, and how industry can be involved in that decision-making.