Red No. 40 Food Dye: Understanding the Risks

A commonly used food dye, Red No. 40, is poised to be eliminated from the U.S. food supply in the next two years. But what do we actually know about the risks associated with it?

Artificial food dyes have been on the scientists' and regulators' radar since the 1970s, when the first evidence suggesting their risks posed to children came into light.

The artificial food dye Red No. 3 was banned earlier this year under Joe Biden's administration. Soon after Robert F. Kennedy, Jr. stepped in as Secretary of Health and Human Services, his health agencies banned two synthetic food colorings: Citrus Red No. 2, used to color orange peels, and Orange B, approved only for hot dog and sausage casings.

Six more dyes, including Green No. 3, Yellow No. 5, and Red No. 40, will be phased out from the food supply by the end of 2026.

"For too long, some food producers have been feeding Americans petroleum-based chemicals without their knowledge or consent," JFK Jr. said.

However, there appears to be no clear consensus on the harms posed by these dyes. Joseph Borzelleca, a toxicology professor whose 1987 industry-funded study on the Red No. 3 dye risks formed the basis for the ban, told KFF News he has 'no problem' with his kids and grandkids consuming the coloring as it doesn't cause cancer.

But not all dyes are made equal. We look into the potential risks of Red No. 40, also called Allura Red, the coloring found in nearly one-third of foods and beverages marketed for children.

Red No. 40 and potential health risks

According to the Joint FAO/WHO Expert Committee on Food Additives, the dye does not present a health concern neither for children nor for other age groups. Its acceptable daily intake (ADI), the amount that can be consumed every day without causing health issues, is up to 7 mg per body kilogram.

A 2021 review by the California Environmental Protection Agency concluded that human clinical trials indicate that artificial food dyes are associated with adverse neurobehavioral effects, such as inattentiveness, hyperactivity, and restlessness in sensitive children. However, it emphasized that children vary in sensitivity to synthetic food dyes.

Meanwhile, evidence in mice suggests that synthetic dyes can affect activity, memory and learning. Some studies show that the consumption of dyes may lead to changes in the brain's neurotransmitter systems, as well as microscopic changes in brain structure. However, the findings in animal studies do not always translate into humans.

One study in mice discovered that Red No. 40 may damage DNA, and, when consumed in a high-fat diet, lead to gut dysbiosis and low-grade inflammation in the colon, the longest part of the large intestine. As continuous colonic inflammation may contribute to cancer development, the authors hypothesized that the increasing use of the dye in food may play a role in rising cases of early-onset colorectal cancer.

Another study in animal models suggests that Red No. 40 harms gut health and causes inflammation, potentially triggering inflammatory bowel diseases (IBD), such as ulcerative colitis. However, there's no evidence of such a relationship in humans.

Some experts point out that many animal studies indicating cancer risk are based on high-dose exposure to food dyes. In other words, these doses may be higher than the amounts humans get from food.

Red No. 40 is among the three dyes that have been found to be contaminated with benzidine and other carcinogens. Studies have shown that workers chronically exposed to high levels of benzidine are more likely to develop cancer, especially of the urinary bladder, according to the Centers for Disease Control and Prevention (CDC).

Analysis by the Center for Science in the Public Interest, a consumer advocacy group, concludes that there's 'controversial and inconclusive' evidence that Red 40 accelerates the appearance of tumors in mice. And because its use is associated with hypersensitivity reactions and hyperactivity in children, the dye should not be used in foods,' according to the group.

How can the ban help?

Changing the color additives in food from synthetically-derived to naturally-derived ones will not automatically make the foods healthier, since they are used in very small concentrations, according to Melissa Wright, food safety expert at Virginia Tech.

Because long-term effects of naturally-derived color additives aren't well studied, Wright says we may find ourselves at this same crossroads in the future.

The best case scenario is that banning these color additives will drive consumers to eat more whole, unprocessed foods that are naturally brightly colored and healthier. It's the highly processed foods that are most unhealthy for the consumer, not the color additives themselves.

Melissa Wright, MS

Highly processed or ultra-processed foods (UPFs) are those formulated mostly or entirely from substances derived from foods and contain ingredients we wouldn't use to cook at home.

Consuming large amounts of UPFs like packaged snacks, processed meats, and sweetened beverages has been associated with 32 types of health problems, such as heart disease, cancer, and obesity.

However, there's ongoing discussion about what constitutes UPFs, as some foods that undergo processing can still be a part of a healthy diet.

The problem of petroleum-based food dyes

Artificial food dyes are derived from petroleum, which has become one of the major arguments for their elimination. However, the petroleum narrative attracted some criticism from the scientific community.

Immunologist Dr. Andrea Love points out in her Substack that petroleum doesn't equal gasoline. Instead, it is a mixture of chemicals that came from the partial decomposition of dead marine organisms. These chemicals are made up of hydrogen and carbon and are called hydrocarbons.

When these chemicals are broken down, purified, and reassembled, they become building blocks for many wellness products, including dietary supplements like vitamin A, D, or E, mineral oil, and medications such as aspirin.

Love writes that even methylene blue, a medication approved for a blood condition called methemoglobinemia and promoted by RFK Jr. himself, comes from petroleum.

Are natural food dyes better?

Synthetic food dyes have several advantages over natural colorings. They are more stable, cheaper, and offer a greater color variety.

However, natural does not automatically mean safer, Jessica Knurick, a registered dietitian with a PhD in nutrition science, writes in her Substack.

For example, the natural colorant carmine, made from crushed cochineal insects, can cause serious allergic reactions. Moreover, turmeric and certain botanical extracts may trigger sensitivities in people with plant-based allergies.

It is noteworthy that at least four synthetic dyes, including Red No. 40, can cause hypersensitivity reactions, adding to the long list of potential health risks posed by the substance.

Is Red No. 40 banned in other countries?

There's a common misconception that Red No. 40 and other synthetic dyes are banned in the European Union and elsewhere.

The European Food Safety Authority (EFSA) considers Red No. 40, which is called E 129 in the European Union, safe below the ADI of 7 mg/kg bw/day. However, products containing the dye must include a warning that it may have an adverse effect on activity and attention in children.

Health Canada also allows the use of Allura Red but limits its amounts in foods.

The takeaway

Much evidence of the risk of Red No. 40 comes from animal studies involving much higher exposure to the coloring than humans get from food. However, it doesn't mean that these potential risks won't be proven real in the future. Meanwhile, high consumption of ultraprocessed foods rather than artificial dyes may be a more pressing health concern.