During a press conference on Tuesday, Health and Human Services Secretary Robert F. Kennedy Jr. unveiled a plan to start phasing out eight synthetic food dyes in the American food supply.

HHS and the U.S. Food and Drug Administration are looking to revoke authorization for two synthetic food colorings and to work with food manufacturers to eliminate six remaining synthetic dyes used in foods such as cereal, snacks, ice creams and yogurts.

Kennedy has previously been vocal about his opposition to artificial dyes, claiming they are harmful and calling for them to be removed from foods and beverages.

Studies have linked dyes to behavioral changes as well as to cancer in animals, suggesting this may extend to humans.

Some nutritionists and dietitians say that it’s best to avoid artificial food dyes, while others say more research needs to be done and the potential negative effects are still unclear.

What are synthetic dyes and where are they found?

Many years ago, some synthetic dyes were produced from by-products of coal processing, according to the FDA. Today, many dyes are petroleum-based and made through chemical processes.

They appear in many different types of foods including candies, ice cream, frozen desserts, crackers, chips, energy bars, cereals, beverages and more.

Halle Saperstein, a clinical dietitian at Henry Ford Health in Detroit, told ABC News her research has found there are about 36,000 products with Red No. 40, about 8,000 products that contain Red No. 3 and about one in 10 products that contain another type of synthetic food dye.

“The other thing to note is that many products contain multiple petroleum food dyes, not just one specific one,” she said.

Sandra Zhang, a registered dietician nutritionist and pediatric dietitian at the Frances Stern Nutrition Center at Tufts Medical Center in Boston, said synthetic dyes are very prevalent and are mostly used in packaged, processed foods that can be found in supermarkets and grocery stores.

“Synthetic food dyes are not found in nature, so they are man-made entirely,” Zhang said. “And so, they have no nutritional properties or benefits whatsoever. They are made only to enhance the appearance of foods.”

What have studies shown?

Research has suggested that some synthetic food dyes may be associated with behavioral issues in children and teenagers.

A 2012 meta-analysis from Oregon Health and Science University found artificial food colors may affect children’s behavior and exacerbate symptoms of attention-deficit/hyperactivity disorder.

Another 2012 study found artificial food coloring is not a major cause of ADHD but can affect children whether or not they are diagnosed with the condition.

Additionally, a 2022 analysis from the California Environmental Protection Agency and two California universities found that there may be an association between synthetic food dyes and behavioral issues even children without a diagnosed behavioral disorder.

In 2019, the FDA said an advisory committee did not establish a “causal link” between synthetic color additives and behavioral effects, but did recommend further research on the issue.

Are synthetic food dyes safe?

Experts are divided on the issue. Saperstein said she sees a credible link between behavior and synthetic food dye consumption based on the studies she’s read.

Zhang said she’s not sure if there’s a link between behavioral issues and synthetic food dyes and that more research needs to be done.

“At least from my patient care experience, I’m not observing … a kid consuming Gatorade every day makes a huge difference” in their behavior, she said.

She added, however, that scientific research linking dyes to neurobehavioral changes was done on animals.

Whether or not synthetic dyes are safe to consume, experts agree it is best to limit artificial food coloring consumption when possible.

Jennifer Pomeranz, an associate professor of public health policy and management at NYU School of Global Public Health, said she believes there is no need for artificial food dyes in the food supply because they don’t act as preservatives and they don’t have any nutritional benefits.

“There are natural dyes that [companies] can use,” she said. “And frankly, there’s really no need for such a brightly colored food supply.”

Earlier this year, under the administration of former President Joe Biden, the FDA said it was moving to ban the use of Red No. 3 in foods, beverages and medications after it was found to cause cancer in rats.

On the heels of Kennedy’s Tuesday announcement about eliminating other synthetic dyes, the International Association of Color Manufacturers, the trade association for the color additives industry, released a statement criticizing the HHS decision.

“Color additives have been rigorously reviewed by global health authorities, such as the U.S. Food and Drug Administration, the European Food Safety Authority, and the Joint FAO/WHO Expert Committee on Food Additives, with no safety concerns,” the statement read. “Requiring reformulation by the end of 2026 ignores scientific evidence and underestimates the complexity of food production”

What about natural alternatives?

During Tuesday’s press conference, FDA Commissioner Dr. Marty Makary mentioned watermelon juice and carrot juice as natural alternatives to synthetic dyes.

Some food manufacturers use concentrated forms of natural pigments found in fruits and plants — such as beets, blackberries, paprika, saffron, tamarind and turmeric — as dyes.

As the food industry shifts to natural dyes, more research should be done to study their safety and to formulate regulations on the concentration levels, Zhang said.

The FDA said on Tuesday it is fast-tracking the review of four new natural color additives: calcium phosphate, Galdieria extract blue, gardenia blue and butterfly pea flower extract.

Gardenia blue and butterfly pea flower extract come from plants, Galdieria extract blue comes from algae and calcium phosphate is a chemical compound.

Expert say food companies use synthetic dyes to color their products because they are cheaper compared to natural dyes. Some companies have stated their products are safe for consumption, and they are following federal standards set by the FDA.

Saperstein said another reason companies might use synthetic dyes is psychological, because people are more drawn to brightly colored foods than foods with muted colors.

“We’ve seen stories of companies switching [to natural dyes] and they feel it’s not bright enough, so they switch back,” Pomeranz said.