Synthetic Dyes in our Food

What are petroleum-based synthetic dyes and how might natural products fill the gap in colorants?

Apr 23, 2025

They’re the secret behind the vibrant red pop of maraschino cherries and the enduring green in canned green beans. But these colorants are neither natural nor nutritious—and the U.S. food system is long overdue for a reassessment of the synthetic additives we allow in our food. Many of these dyes are already banned in other countries due to health concerns.

Yesterday, the FDA announced its intent to phase out petroleum-based synthetic dyes from the U.S. food supply (read the full press release here). In today’s post, I’ll break down which dyes are affected and what we know about their impact on human health. I’ll also share examples of natural, fruit and vegetable–based colorants already used in in other countries—offering a safer, plant-based alternatives.

How are Dyes Made from Petroleum?

Synthetic dyes do not occur in nature. These petroleum-based synthetic dyes are made by breaking down the component parts of crude oil (complex hydrocarbons) into smaller molecules. Then, using the tools of synthetic chemistry, new molecules are made by rearranging these various parts. A common group of such molecules are the “azo” dyes, which are made by coupling a diazonium salt with another compound. Several dyes included in the FDA press release fall into this category: Citrus Red No. 2, Orange B, FD&C Red No. 40, FD&C Yellow No. 5, and FD&C Yellow No. 6. Azo dyes have been linked to various cancers and allergies.

The FDA Plans to Revoke Authorization for Two Dyes

Two dyes are on the list to have their authorization revoked:

Citrus Red. No. 2 is used to color the skin of oranges, but not for oranges intended for processing—the idea being that it shouldn’t be eaten. It is listed as a group 2B carcinogen based on evidence of causing cancer in lab animals.
Orange B is approved for use in hot dog and sausage casings, but based on what I can find online, it hasn’t been in the food system since the 1970s when the only company that manufactured it closed.

The FDA Plans to Eliminate Six Remaining Synthetic Dyes

FD&C Green No. 3—also known as Fast Green HCF. This turquoise colored dye is used in a wide array of food products, including candy, cereal and Jello. To my surprise, it is even used in some canned foods, such as green beans, to maintain the green color of the vegetable! This dye is commonly used in scientific experiments to stain proteins. I couldn’t find any clinical studies on this dye.
FD&C Red No. 40—aka Allura red AC. This red dye has been linked to allergic reactions as well as hyperactivity in children. One study “found that children, especially ages 5–9, have the highest exposure to Allura Red AC, primarily from juice drinks, soft drinks, icings, and ice cream cones,” with lower income consumers having higher intake. This 2024 article in the scientific journal Carcinogenesis makes a compelling case for how this particular dye acts on multiple body systems—from the gut microbiome to inflammatory cascades—calling for more research that could reveal its role as a carcinogen (cancer-causing) agent.
FD&C Yellow No. 5—aka Tartrazine. Sensitivity to this yellow-colored dye has been reported beginning in the 1970s, with symptoms including asthma and hives. It is found in various foods, ranging from cereals, cake mixes, beverages (Mountain Dew, Gatorade, Kool-Aid), “cube” soups, rice mixes, mustard, flavored chips (Doritos, Nachos), yogurt and more! See the full list here courtesy of the Contact Dermatitis Institute’s allergen database.
FD&C Yellow No. 6—aka Sunset yellow FCF. This orange-yellow dye can be found in instant noodles, biscuits, jams, chips, sodas, sauces, and more. I couldn’t find much relevant research on this one, but there was one study of interest in which researchers delivered injections of the dye to chicken eggs and monitored for developmental changes, finding chicks with the dye had enlarged spleens as well as other embryonic developmental changes.
FD&C Blue No. 1—aka Brilliant blue FCF. Like tartrazine, this blue dye has also been linked to allergic reactions including rashes, hives, and nasal congestion. It is included in breakfast cereals, juice drinks, sodas and desserts. It is also used in e-cigarette (vape) liquids. Research in animals found that while it doesn’t cause DNA damage, there was some evidence of changes to the chromosomes in two studies. This review article also notes that in addition to causing allergic reactions, several studies have found links to convulsions, gastrointestinal tumors, as well as attention deficit and hyperactivity in children.
FD&C Blue No. 2—aka Indigotine. This blue dye can be found in various products, from maraschino cherries to sausage, ice cream, breakfast cereals, baked goods and more. It is also used in ingested drugs. While animal studies have found that it is not genotoxic or teratogenic, there are concerns about a significant increase in brain and mammary gland tumors observed in rats.

Accelerating the Plan to Remove FD&C Red No. 3

There was a previously set deadline (2027-2028) for companies to remove FD&C Red No. 3—aka erythrosine—from the food system, but the FDA is now asking them to move faster. This dye is used in red and pink foods, including maraschino cherries, strawberry flavored dairy products, candy, beverages, baked goods and more. The FDA revoked authorization of this dye in January 2025 due to a link to cancer in male rats. The notice of revocation cites the The Delaney Clause, which specifies that additives a causal link to cancer in animals or humans cannot be FDA authorized:

The Delaney Clause, enacted in 1960 as part of the Color Additives Amendment to the FD&C Act, prohibits FDA authorization of a food additive or color additive if it has been found to induce cancer in humans or animals.

What About Natural Colorants?

Nature is an incredible chemist, offering a wide array of colorants that also provide health-promoting antioxidant properties. Take, for example, the vibrant orange carotenoids found in carrots or the anthocyanins in dark purple fruits and vegetables. Then there’s the red of paprika, the orange of turmeric, and so on. Of course, the real health benefits come from eating these foods in their natural, whole form—not as isolated components repurposed as cogs in the ultraprocessed food industry.

The Takeaway

Synthetic dyes are pervasive in some of the most commonly consumed foods by American children—juice drinks, breakfast cereals, flavored yogurts, and more. Even well-intentioned parents often fall prey to the marketing tactics of the ultraprocessed food industry. With store shelves flooded with these products, finding truly healthy alternatives has become exceptionally challenging for consumers.

Strangely, from what I can glean on the Pubmed biomedical research database, most of these dyes haven’t been subjected to extensive scientific research—and of the studies published, some authors of reviews raised concerns about papers sponsored by industry (alluding to potential conflicts of interest)!

The bottom line: We need to more rigorously and scientifically vet any new dye or additive thrown into our food system in the future. I'm glad to see the FDA taking steps to remove these petroleum-based synthetic dyes from our food supply. I hope they will also extend these efforts to cosmetics and pharmaceuticals, where many of these dyes are still in use. If we can also address the excessive sugar content and other additives common in ultraprocessed foods, we might finally begin to make real progress in reducing the prevalence of chronic diseases across the country.

Yours in health, Dr. Quave