Red Dye in Foods: Uses and Health Risks


The Food and Drug Administration regulates food dyes. But does this mean that they’re safe to eat? Not exactly, according to researchers.

Red gummy bears sorted diagonally on bright blue background. Minimal creative concept. Flat lay.

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Recently under scrutiny has been red dye 40, a (you guessed it) red-colored food additive found in common pantry staples – some of which aren’t red in color – that has been suspected to increase risks for bladder cancer and ADHD.

What Is Red Dye 40?

Red dye 40 is a synthetic preservative used to color food products red. It’s also known as Allura Red AC, or C18H14N2Na2O8S2, if you go by molecular formulas.

Like most food dyes, red dye 40 was originally synthesized from coal tar and is now made from petroleum. It’s made up of chemical bonds that can be toxic when heated to decomposition, a process in which chemicals can change form.

Some studies have also revealed that red dye 40 also contains carcinogens like p-credine, which is linked to cancers in animals, and benzidine, which the National Cancer Institute links to bladder cancer.

Food With Red Dye 40

You can check if a product contains red dye 40 by looking at its ingredient list. Dyes tend to be listed toward the end. Red dye 40 may be listed as a couple of names, including Red 40, Allura Red, Red 40 Lake, INS No. 129 and E129. It can also be found in some cosmetics and pharmaceutical products.

Common foods containing red dye 40 include:

  • Cereals, including Fruit Loops.
  • Sodas, including Pepsi.
  • Condiments.
  • Red Jell-O
  • Chocolate pudding.
  • Dairy products.
  • Baked goods.
  • Chocolates.
  • Candies, including Skittles.
  • Juice.
  • Gummies.
  • Sports drinks, including red Gatorade.

Not all products that contain red dye 40 are red in color, but those that are tend to have a vibrant hue – bright enough to leave a stain on your tongue or lips after you eat it.
There is a reason that red dye 40 can stain the mouth, whereas a natural colored red food like a strawberry is less likely to do so. This is due to a chemical reaction between the dye and proteins within the human body.

“The dye actually binds to proteins on your skin, on your tongue, and your body has to physically metabolize that,” explains Dr. Jennifer Linehan, a urologic oncologist at Saint John’s Cancer Institute in Santa Monica. “With a strawberry, the tissue of the fruit is red and (any stains) fade away relatively quickly.”

Unfortunately, while a lollipop may seem like a fun alternative to Mom’s lipstick (at least, for a child playing pretend), these lip stains aren’t just fun and games. That’s because when your body breaks down the dye, it releases more than just the color, explains Linehan. It releases those carcinogenic ingredients, like benzidine.

Is Red Dye 40 Bad for You?

One of the things that makes red dye 40 so nefarious is benzidine, a cancer-causing chemical found among its ingredients. In addition to red dye 40, benzidine has been found in yellow No. 5 and yellow No. 6 food color additives. On its own, benzidine has been linked to increased risks of bladder cancer, and the primary way people can be exposed is through ingestion.

Not everyone who is exposed to carcinogens will develop cancer, but exposure increases their risk. 

“That’s why you have some people who’ve smoked for their entire lives and they never get cancer, and other people who smoked for five years and have two types of cancers,” she adds.

Typically, for someone to develop cancer from carcinogen exposure, two things need to be working against them: exposure and genetics, Lineham explains.

“It’s usually what we call a two hit theory,” she says. “One: you have to have a mutation that’s going to give you cancer. Two: you need something to turn that on.”

That “something” could be smoking, radiation or – in the case of red dye – exposure to benzidine. 

Benzidine can be found in non-food dyes and was formerly used to stain textiles, paper and leather. The U.S. largely phased out these uses in commercial spheres in the 1970s, and it is no longer used in medical labs, the rubber industry or the plastic industry, according to the National Cancer Institute.

People can be at higher risk for benzidine exposure if they work in coal or oil refineries. Linehan witnessed this with a recent patient, a 48-year-old man, having formerly worked in an oil factory, who came in with a high-grade bladder cancer. “He was cleaning tanks with these benzidine products – cleaning the metal tanks where they would store oil or fuel – and he got a very aggressive bladder cancer, and I’m almost certain that’s what it’s from.”

She adds that people like her patient, who work hands-on with benzidine chemicals, likely have a much higher exposure and risk level than people who are only coming into contact with the chemical through eating red dye.

“If they’re doing that job every day, they’re exposed to fumes, smells, sucking it in, getting it on their skin,” says Linehan. “They’re going to be at a much higher risk for cancer than somebody who may be eating a red lollipop.”

But, she adds, that’s not to undermine red dye 40’s risks in food.

“With synthetic food coloring, if it has a benzidine product in any variation, it is carcinogenic,” says Linehan. “What’s difficult for us as medical professionals to assess is how much of that exposure do you need? How much do you have to take for it to actually have an effect?”

Unfortunately, the answer is unknown. And for now, benzidine levels in red dye 40 are low enough for the FDA to consider the product safe to keep on the market.

Red Dye 40 Side Effects

Among other complications, studies say red dye 40 may increase risks for ADHD in children. Notably, a 2015 report by the Journal of the American Academy of Children and Adolescent Psychiatry estimated about 8% of children with ADHD may have symptoms related to synthetic food colors.

This research is inconclusive, however, and not all institutions back it up (hint: the FDA). According to a 2019 review by the FDA, a causal link between consuming red food dye and developing ADHD had not been established.

“The FDA has not formally noted a connection between red dye and ADHD in children, but there is some data to point towards a possible connection,” says allergist and immunologist Dr. Farah Khan, who is with the Nationwide Children’s Hospital in Columbus, Ohio. “We’re still learning about food additives and in the world of allergy and immunology, we don’t have any validated way to test for the behavioral concerns that arise.”

Khan adds that parents often raise concerns to her about how food coloring may be impacting their child’s behavior and ask her whether there’s a way to test their child for a food dye allergy.

“Unfortunately the answer is always ‘No, I’m sorry, we can’t test for this,’” says Khan. This is due to two reasons she adds.

First: A typical allergic reaction comes from what’s called an “IgE mediated symptom and immune response.” This doesn’t happen in the presence of red food dyes.

And second: Allergists do not currently have a standardized, validated test to perform for patients who are concerned about a red dye allergy.

“This can be really frustrating for patients and parents to hear who are trying to navigate their symptoms and come to an answer to help improve their quality of life,” Khan adds.

Due to the inability to test and affirm an allergy, Khan recommends parents or patients keep a good diary to track their responses to suspected trigger foods (or dyes) to determine the culprit of their symptoms and cut things out of their diet if necessary.

Reducing Risks From Red Dye 40

While the extent of red dye 40’s health risks are uncertain, there’s no immediate harm in cutting out artificial food dye from your diet, as long as you aren’t cutting out major food groups with it.

What’s clear is, “these compounds are high risk,” says Linehan. “How much you’re getting when you eat a lollipop? That’s a different story. But I’d definitely try to avoid it if I can.”

Alternatives to red dye 40

To lower your exposure to red dye 40, consider making the following changes:

  • Buy uncolored snacks and beverages. Look at the ingredient lists. Steer clear from ones that list red dye or other artificial dyes and colorings.
  • Make your own red recipes. Use natural ingredients like beet juice, cranberry juice, cherries, red cabbage or another potent red fruit to color your food.


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