What will Red 40 do to your body? An in-depth look at its potential health effects

November 27, 2025 •

4 min read

According to a 2021 report from California's Office of Environmental Health Hazard Assessment, synthetic food dyes like Red 40 are linked to adverse neurobehavioral effects in children. Beyond behavioral issues, many people are asking: what will Red 40 do to your body, and what other health concerns does this common additive present?

Quick Summary

An exploration of Red 40's potential health impacts, including links to hyperactivity in children, allergic reactions, digestive inflammation, and possible carcinogenic contamination. Reviews research and offers guidance for consumers.

Key Points

Behavioral Effects: Studies have linked Red 40 to increased hyperactivity and worsened ADHD symptoms in sensitive children.
Gut Health Disruption: Research in mice indicates Red 40 can alter the gut microbiome, increase intestinal inflammation, and potentially raise the risk of inflammatory bowel disease.
Allergic Reactions: Though rare, some individuals may experience allergic reactions, including hives, swelling, or migraines, after consuming Red 40.
Carcinogen Contamination: Red 40 can be contaminated with benzidine, a potential carcinogen, and studies have shown it can cause DNA damage in animal models.
Check Labels: The most effective way to avoid Red 40 is by carefully reading food labels for ingredients like Allura Red AC, as it is found in many processed foods and beverages.
Global Regulation Differences: Unlike in the U.S., European regulations require a warning label on products containing Red 40 regarding potential behavioral effects in children.
Individual Sensitivity: The effects of Red 40 can vary significantly based on individual sensitivity, with some people experiencing no adverse reactions while others show marked symptoms.

Understanding Red 40: The Controversial Food Dye

Red 40, also known as Allura Red AC or FD&C Red No. 40, is a synthetic color additive derived from petroleum. It is one of the most widely used food dyes in the United States and is found in thousands of consumer products, from sugary cereals and fruit snacks to medicines and cosmetics. Its primary function is to make products visually appealing and consistent in color. While regulatory bodies like the FDA currently deem Red 40 safe at approved levels, mounting research and consumer concern have called its long-term safety into question.

Potential Neurological and Behavioral Effects

One of the most debated and studied effects of Red 40 concerns its impact on behavior, particularly in children.

The Link to Hyperactivity and ADHD

For years, some parents and researchers have suggested a link between artificial food dyes and increased hyperactivity in sensitive children. Several studies have examined this connection:

The 2007 Southampton study found a link between a mix of food dyes (including Red 40) and hyperactivity in children.
A 2021 review conducted by California's OEHHA found that synthetic food dyes are associated with adverse neurobehavioral effects, including inattentiveness and restlessness in some children.
Some research suggests that eliminating artificial dyes from the diets of children with ADHD can lead to an improvement in symptoms.

Experts acknowledge that not all children are sensitive to these dyes. For those who are, however, the dye could push them over a diagnostic threshold or exacerbate existing symptoms. The precise mechanisms are still under investigation, but theories suggest that Red 40 may affect neurotransmitter levels like dopamine and serotonin in the brain.

Impact on Gut Health and Inflammation

Emerging research suggests that Red 40 may have a significant effect on the gastrointestinal system, a crucial part of the body's overall health.

The Gut Microbiome and IBD Risk

Altered Gut Bacteria: Studies in mice, including one published in Nature Communications, have shown that chronic exposure to Red 40 can disrupt the gut microbiome. This delicate ecosystem of microorganisms is vital for digestion, immunity, and even mood regulation.
Increased Inflammation: The same studies indicate that Red 40 can lead to low-grade inflammation in the colon, potentially increasing susceptibility to inflammatory bowel diseases (IBD) like colitis.
Serotonin Production: One study observed that the dye increased serotonin production in the gut of mice, which altered the microbial composition and heightened inflammation risk.

Allergic Reactions and Hypersensitivity

While rare, allergic or hypersensitivity reactions to Red 40 have been reported in some individuals. Symptoms can range from mild to severe and may include:

Skin irritation, such as hives or itchy skin
Facial or oral swelling
Respiratory issues, including wheezing or asthma
Migraines or headaches
In rare and severe cases, anaphylaxis

Concerns About Carcinogenic Contaminants

Red 40 is produced using chemicals that have raised concern among health experts. While the FDA requires that the final product meets safety specifications, the presence of certain contaminants is a known issue.

Benzidine: Benzidine is a known animal and human carcinogen that can be a contaminant in Red 40 production. Though present in tiny amounts, the potential for long-term exposure is a concern for some groups.
DNA Damage: A 2023 study found that Red 40 caused DNA damage and colonic inflammation in mice, raising questions about potential cancer links, though more research is needed to determine the relevance to human health.

Comparison: Red 40 vs. Natural Alternatives


Feature	Red 40 (Allura Red AC)	Natural Alternatives (e.g., Beet Juice, Carmine)
Source	Petroleum	Plants (beets), insects (cochineal)
Health Concerns	Linked to hyperactivity, allergic reactions, inflammation, and potential carcinogenic contaminants	Carmine can trigger rare allergic reactions in sensitive individuals
Regulatory Status (U.S.)	FDA-approved as safe for consumption in regulated amounts	FDA-approved as exempt from batch certification; approved by FDA
EU Labeling	Requires a warning label: "May have an adverse effect on activity and attention in children"	Generally does not require a warning label
Appearance	Bright, vibrant, consistent red color	Can vary in color intensity and stability depending on the source
Processing	Synthetic chemical process	Extracted from natural sources

How to Reduce or Avoid Red 40

For those concerned about the effects of Red 40, reducing consumption is straightforward. A great starting point is to read product labels carefully, looking for "Red 40," "FD&C Red No. 40," or "Allura Red AC".

Food Categories to Check

Beverages: Many sodas, fruit punches, and sports drinks contain Red 40.
Snacks: Candies, gummies, fruit snacks, and colored chips are common culprits.
Cereals: Colorful breakfast cereals, especially those marketed to children, often contain artificial dyes.
Condiments and Sauces: Salad dressings, barbecue sauces, and other condiments can contain Red 40.
Baked Goods: Packaged cakes, cookies, and icing frequently include artificial colors.

Alternative Strategies

Look for Natural Alternatives: Many food brands now offer products with natural coloring from sources like beet juice, paprika, or carmine.
Choose Whole Foods: Prioritizing whole, unprocessed foods like fresh fruits and vegetables is the most effective way to avoid all synthetic additives.

Conclusion

The question of what will Red 40 do to your body does not have a simple answer. While regulatory bodies consider the dye safe at current levels, the body of scientific evidence is growing, suggesting potential links to neurobehavioral issues, gut inflammation, allergic reactions, and possible carcinogenic contamination. As with any food additive, individual sensitivity plays a key role. For those with concerns, especially parents of children exhibiting sensitivities or individuals with inflammatory conditions, a mindful approach to checking labels and seeking natural alternatives can be a prudent strategy. This is particularly relevant considering that the additive serves an aesthetic rather than a nutritional purpose.

For more in-depth research on food dyes and health effects, consider reviewing the comprehensive assessment by the California Office of Environmental Health Hazard Assessment, which you can find by visiting their official website. Office of Environmental Health Hazard Assessment

Frequently Asked Questions

Red 40 is not banned outright in the European Union or Canada, but regulations differ significantly from the U.S. In the EU, products containing Red 40 must carry a warning label stating they 'may have an adverse effect on activity and attention in children'. Many U.K. brands have voluntarily removed it.

There is no conclusive evidence that Red 40 or other food dyes directly cause ADHD. However, multiple studies and anecdotal reports suggest that the dye can exacerbate or trigger hyperactivity and other behavioral symptoms in children who are already sensitive or have a predisposition to ADHD.

Red 40 is prevalent in many processed foods, including candies, fruit snacks, colorful cereals, sports drinks, and baked goods. It is also found in some yogurts, condiments, and over-the-counter medications.

To avoid Red 40, check the ingredients list on packaged foods for 'Red 40,' 'FD&C Red No. 40,' or 'Allura Red AC.' Choosing whole, unprocessed foods and opting for products that use natural colorings like beet juice are also effective strategies.

Natural alternatives to Red 40 include beet juice for red coloring, paprika for a reddish-orange hue, and annatto for yellow-orange. Some companies also use carmine, which is derived from insects.

Allergic reactions to Red 40 are relatively rare. When they do occur, they are most often mild and involve skin symptoms like hives and swelling. In very sensitive individuals, more severe reactions are possible, but uncommon.

Most food color additives are poorly absorbed and are typically excreted from the body within 36 hours through urine and feces. However, the immediate effects on sensitive individuals can occur much sooner.