Is Red Dye 40 Causing Inflammation? What the Research Really Says

Key Takeaways

• Red Dye 40 is used in many foods and drinks, including candies, breakfast cereals, baked goods, sodas, confectioneries, sauces, flavored dairy products, and more. 
• Public concern has grown about the adverse effects of Red Dye 40. Limited research suggests it may have carcinogenic effects and cause behavioral problems in children. 
• The FDA has announced a mission to eliminate Red Dye 40 from the industry by working with companies. 
• You can lower your exposure to Red Dye 40 by reading nutrition facts labels.

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Color additives are used in foods, drinks, drugs, and cosmetics. Manufacturers add coloring to make foods and drinks more appealing. 

The U.S. Food and Drug Administration (FDA) approved Red Dye 40 in 1971. Since then, the dye has been used in many foods and drinks.

Recent studies warn against Red Dye No. 40. This petroleum-based synthetic dye has been linked to inflammation, allergic reactions, hyperactivity, bowel diseases, and even colorectal cancer risk.

Understanding Red Dye 40

Red Dye 40 is a coloring additive made from coal and petroleum products. It gives shades of red color to foods and drinks.¹ 

The FDA approves and regulates the use of food colorings based on the current evidence available at the time. These regulations may change as new evidence emerges. One example is Red Dye 40, also known as Allura Red AC, FD&C Red No. 40, Food Red 17, C.I. 16035, or E129.¹

In April 2025, the FDA stated that it’s working to remove synthetic dyes, including FD&C Red No. 40, fromthe  food supply. Other synthetic dyes also included in the list: FD&C Red No.3, Green No. 3, Yellow No. 5, Yellow No. 6, Blue No. 1, and Blue No. 2.²

A study looked at 810 products. Of those, 43% contain artificial food coloring, and almost 30% contain Red 40.³

Here are some products that might contain Red Dye 40:⁴

• Pastry decorations and coatings
• Cereals 
• Chewing gum
• Baked goods
• Flavoured fermented milk products
• Edible cheese rinds
• Desserts
• Jams, jellies, marmalades, and fruit spreads
• Ice cream
• Seafood
• Breakfast sausages
• Appetizers
• Sauces
• Seasonings
• Soups
• Luncheon meat, such as ham slices 
• Meat replacements
• Sugar-sweetened beverages and other flavoured drinks, such as energy drinks and sports drinks 
• Alcoholic beverages

Synthetic dyes are widely used because they are cost-effective for manufacturers, stable under heat and light, give vibrant color, and can be used in various products. These qualities make them advantageous compared to natural food dyes.

Manufacturers can use Red 40 since the FDA has approved the dye and monitors its use in products by testing a sample from every batch. The FDA does this to ensure manufacturers use the dye within acceptable limits. 

The FAO/WHO Joint Expert Committee on Food Additives (JECFA) and the European Food Safety Authority (EFSA) have found no significant health risks associated with the consumption of Red Dye 40. The dye is considered safe when consumed within the Acceptable Daily Intake (ADI), which is set at 0–7 mg per kilogram of body weight.⁵⁻⁶

However, EFSA also acknowledges that Red 40 may be overconsumed by some children, which could potentially lead to behavioral problems such as hyperactivity.⁶

Scientific Studies Linking Red Dye 40 to Inflammation

When there is a harmful substance, our immune system responds with inflammation. Acute (short-term) inflammation is crucial to eliminate harmful substances or infections. However, when there is chronic exposure, and thus chronic inflammation, cell damage and diseases can develop.

Recent animal studies link synthetic food colors to inflammation in the gut. Researchers hypothesize that the consumption of Red Dye 40 can cause inflammation in gut cells, increasing the risk of colorectal cancer. This may be potentially harmful for people with inflammatory bowel diseases (IBD).

One study looked at 10 months of exposure to Red Dye 40 in mice fed a high-fat diet. Red Dye 40, combined with the high-fat diet, disturbed the gut microbiome and caused inflammation in the colon and rectum. Researchers concluded that chronic inflammation caused by Red Dye 40 may pose a risk for gut health and colorectal cancer.⁷ 

In a study, researchers examined food coloring consumption and the development of cancer over the following years. Among 102,435 adults, 3,511 developed breast, prostate, or colorectal cancer. Researchers link these cases to cell damage and inflammation, potentially caused by food coloring. An artificial food dye, carmine (E120), was associated with a 21% higher risk for breast cancer, and plain caramel (E150a) was associated with a 53% higher risk for colorectal cancer when the lowest and highest exposure to these food colorings is compared.⁸

These studies point to synthetic food dyes potentially having harmful effects. However, studies specific to each individual synthetic dye are limited. We need more research to fully understand their effects on humans for long-term exposure.

Potential Health Implications

Red Dye 40 is not banned. However, the FDA has announced that it is working with the industry to eliminate six synthetic food dyes, including Red Dye 40. This decision is based on emerging evidence and growing public health concerns.

We have limited studies looking only at the adverse effects of Red Dye 40. Some clinical studies have linked synthetic food dyes to the symptoms of Attention Deficit/Hyperactivity Disorder (ADHD) in children.⁹

In a case study, a person reported throat closure and facial rash after drinking and eating food that contained red food dye. However, skin tests did not result in symptoms. The person also did not want to undergo oral challenge tests for products that had caused reactions before. Researchers still indicate that Red Dye 40 may cause hypersensitivity reactions.¹⁰

Identifying and Reducing Exposure to Red Dye 40

Red Dye 40 is found in many processed foods, including cereals, jams, sauces, confections, dairy products, flavored drinks, and more. 

A few things you can do to reduce exposure to Red Dye 40:

• Check the ingredient list to find out if a product contains Red Dye 40. Manufacturers are required to list it as "FD&C Red No. 40" or "Red 40." Manufacturers don’t have to list the exact amount of Red Dye 40 used in the product. However, they must list ingredients from most to least present in the product.¹⁻¹¹

• Don't be tricked by the color. Even products that aren’t red can contain Red Dye 40. Food dyes are also used to enhance the natural color of food. For example, strawberry yogurt can contain both strawberries and red dye. That's why it's important to read the label to be sure.

• You can choose organic options, as they can’t contain artificial colors, flavors, or preservatives. Organic foods have a USDA Organic seal on the package. ¹²

• You can limit the consumption of ultra-processed foods and soft drinks where synthetic coloring is most commonly used or consumed. 

• You can make homemade versions of flavored foods. For example, flavored dairy products can contain Red Dye 40. Instead of buying packaged flavored yogurt, you can make it at home using natural colorings such as beetroot powder or blended strawberries.

• Supplements and some medications, such as cough syrups, may also contain Red 40 and other dyes, especially those marketed toward children. If you're taking them regularly, you can ask your healthcare provider for alternatives.¹³

The Bottom Line

Red Dye 40 is commonly used in food products due to its appealing bright red color and low cost for manufacturers. Regulatory bodies consider it safe when used as approved, in permitted products and within specified limits. However, with growing public concern, the FDA aims to eliminate Red Dye 40 from food products in the coming years. You can limit your exposure to Red Dye 40 by reading labels and avoiding products that contain the dye.

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