Jul 13, 2023

The True Danger of Food Dye

Health concerns keep shrinking the roster of approved artificial dyes. But Americans still can't seem to go cold turkey on ultra-colorful foods.

In 1856, an amateur chemist named William Henry Perkin mixed a batch of chemicals that he hoped, in vain, would yield the malaria drug quinine. When Perkin's failed experiment turned purple, a hue so vivid that it could stain silks without fading, he realized he’d stumbled upon a different marvel of modernity: a commercially viable synthetic dye, the first of a new generation of chemicals that would revolutionize the way humans colored their clothes and, soon after, their food.

The edible versions of the chemicals, in particular, were a revelation, offering food manufacturers "cheap and convenient" alternatives to pigments squeezed painstakingly from natural sources such as plants, says Ai Hisano, a historian and the author of Visualizing Taste: How Business Changed the Look of What You Eat. Dyes could keep peas verdant after canning and sausages pink after cooking; they could turn too-green oranges more orange and light up corner-shop candy displays. By the Second World War, synthetic dyes had become, as one grocer put it, "one of the greatest forces in the world" in the sale of foods. And the more foods the chemicals were introduced to, the more the chemicals came to define how those foods should look: the yellow of butter, the crimson of strawberry Jell-O.

Read: Americans’ bizarre relationship with the color of their food

But after hitting a mid-20th-century peak, the roster of synthetic dyes used in Western foods began to shrink. In recent years, European countries have appended warning labels onto the products that contain them; the United States has whittled down its once-long list of approved artificial food dyes to just nine. The FDA is now reviewing a petition to delist Red No. 3, which colors candy corn, conversation hearts, and certain chewing gums and cake icings; California and New York are mulling legislation that could ban the additive, along with several others, by 2025.

The concern is that the dyes add not just colors but a substantial health risk. Several of the compounds have been linked to patterns of hyperactivity and restlessness in kids. Red No. 3 has also been known since the 1980s to cause cancer in rats. The precise explanation for the harm is unclear; research into the issue has been spotty, and "there is no comprehensive set of data that says, ‘This is the mechanism,’" according to Elad Tako, a food scientist at Cornell University. Several respected researchers have even dismissed the evidence as overhyped. More than a century into the dyes’ tenure, "there is not even consensus on the fact that they are dangerous," or what happens when our bodies snarf them down, says Monica Giusti, a food scientist at Ohio State University. Even so, the argument against artificial food dyes seems as though it should be simple: They have no known nutritional benefits and potentially carry several health risks. "We’re talking about something that's cosmetic versus something that is hurting kids," says Lisa Lefferts, an environmental-health consultant who has petitioned the FDA to ban Red No. 3. And yet, the dyes endure—precisely because they offer our foods and our eyes shades that nature never could.

When synthetic food dyes were newer, their shortcomings were hard to miss. One of the colorants’ main ingredients was derived from the by-products of the process that turned coal into fuel—and in the absence of careful scrutiny, some early batches of the dyes ended up contaminated with arsenic, mercury, and lead. Companies also used the dyes to conceal defects or spoilage that then sickened many people. By the 1930s, Congress required, among other safety measures, that government scientists vet the chemicals’ safety and restricted companies to sourcing exclusively from an approved list.

But dangerous chemicals seemed to keep slipping through. In the 1950s, after a batch of Halloween candy sickened several children, FDA scientists found that the culprit was the synthetic dye that had turned the treats orange—a dye so toxic that it caused organ damage and even premature death in animals in labs. The agency hastily banned it and, by the late 70s, axed nearly a dozen other synthetic dyes linked to cancers and organ damage in animals. Today, Americans regularly see just seven artificial dyes in their foods; two others are used very sparingly.

Still, roughly 19 million pounds of the seven prevalent synthetic dyes were certified by the FDA to flood the U.S. food supply in fiscal year 2022—and no one agrees on which colorants pose the biggest threat. In the European Union and the United Kingdom, foods containing any of six synthetic food dyes—including the three most common ones in the U.S.: Red No. 40, Yellow No. 5, and Yellow No. 6—must warn customers that the colorants "may have an adverse effect on activity and attention in children." The FDA, however, has yet to adopt any such posture—even though it's long since delisted Red No. 2, which is still allowed in Europe. Even Red No. 3—which has been linked to both cancer in animals and behavioral issues in kids, and may be one of the most concerning additives remaining in the American food supply, according to Peter Lurie, the president and executive director of the Center for Science in the Public Interest—carries a mixed rap. The FDA banned it from cosmetics and externally applied drugs decades ago but still allows it in food; countries in Europe have restricted its use but don't mind adding it to certain canned cherries to maintain their hue.

On the whole, the International Association of Color Manufacturers, which represents the color-additives industry, told me that the claims around food dyes and health risks aren't sound, pointing out that many of the studies on synthetic colors have yielded conflicting results. The FDA, too, maintains that color additives "are very safe when used properly." The links, to be fair, are tough to study: With behavior-focused outcomes in kids, for instance, "you’re looking at more subtle kinds of changes that you find on a population basis," and some children seem more sensitive than others, further muddying the stats, says Linda Birnbaum, the former director of the National Institute of Environmental Health Sciences and the National Toxicology Program. And some laboratory studies on the chemicals have delivered them into rodents in high doses or via tubes down their throat, making the data's relevance to us a bit shakier. But although some argue that there's not enough evidence to conclude that the dyes definitely pose a peril, others rightly note that there's also insufficient data to conclude that they don't. For all of the pounds of the chemicals we’ve gulped down, "there are still more questions than answers about artificial colorants," says Diego Luna-Vital, a food scientist at the Monterrey Institute of Technology and Higher Education, in Mexico.

Lefferts, the environmental-health consultant, is one of several researchers who’d rather err on the side of caution and expunge the entire current roster of artificial food dyes. The potential losses seem negligible, she told me, and the possible benefits immense. Scientists may not even yet know the extent of the dyes’ issues: Just last year, a group led by Waliul Khan of McMaster University published evidence that Red No. 40 may raise the risk of colitis in mice. But without an outright push from the FDA, manufacturers have little incentive to change their practices. And there's not exactly a clear-cut path toward developing new synthetic colorants with a less dubious safety profile: Without identifying why current dyes might be dangerous, scientists can't purposefully avoid the root problem in future ones, says Thomas Galligan, CSPI's principal scientist for food additives and supplements.

In the background of the fight over artificial dyes, the colorants’ natural counterparts are making a slow and steady comeback. In the EU and the U.K., consumers can find Starburst and M&M's tinted mostly with plant extracts. And in the U.S., Kraft has re-created the artificial-orange hue of its mac and cheese with a blend of annatto, turmeric, and paprika. Recent surveys have shown that a growing contingent of the global population is eager to eat cleaner ingredients—not, as Jim Murphy, the former president of General Mills, once put it, "colors with numbers in their foods."

But in late 2017, Murphy would go on to eat his words, after his company's all-natural version of Trix debuted, then rapidly tanked. Trix traditionalists were horrified at the revamped recipe's muted melange of purple-y reds and orangey yellows, devoid of the greens and blues that General Mills had struggled to naturally replicate; they called it "disgusting," and "basically a salad now." Just two years after pledging to purge its products of artificial additives, General Mills reinstated "classic Trix"—complete with its synthetics-laden ingredient list. A similar story played out with Necco, which removed the artificial dyes from its wafers only to quickly return them; Mars, too, publicly promised to remove synthetics from its American products then let its self-imposed deadline pass without making good.

Natural dyes, it turns out, are still a chore to work with, for the same reasons they were once so easily replaced. They’re expensive to extract and process; their colors are inconsistent, and tend to fade quite fast, especially in the presence of light and heat, Luna-Vital told me. Humans are also limited to what nature has available, and the fickleness of those compounds: They often "change on us," Giusti told me, when researchers mix them into recipes. Sometimes the colors even impart unwanted flavors or funk.

Several companies, including Sensient and Kalsec, told me that they are now trying to introduce modifications or tweaks that enhance natural pigments’ stability and vibrancy to help them compete. But the more tinkering happens, the more these new dyes could start to resemble the ones that researchers want them to oust. Nowadays, even natural colorants "are artificially created, on some level," Hisano, the historian, told me. And although the FDA's regulatory standards assume that plant-, animal-, and mineral-derived dyes will be a safer alternative to synthetics, going as far as to exempt them from certain tests, relying on the simple reassurance that a source is natural is, admittedly, "not the strongest scientific argument," Michael Jacobson, the former executive director of CSPI, told me. Nature-made, after all, has never been synonymous with safe: It wasn't so long ago that bakers were bleaching their breads with chalk and dairy manufacturers were tingeing their milks yellow with lead chromate. ("The FDA's regulations require evidence that a color additive is safe at its intended level of use before it may be added to foods," a spokesperson told me.)

There is, technically, another option—abstaining from adding colors to foods at all. But that would fundamentally transform how we experience our meals. Added dyes and pigments—both artificial and natural—are mainstays not just of sports drinks and packaged sweets but also salad dressing, yogurt, pickles, peanut butter, and dried and smoked meats; they’re what makes farmed-salmon flesh pink. Vision is key to taste: "There's probably no other sensory cue that gives us as much information about what we’re about to eat," says Charles Spence, an experimental psychologist at the University of Oxford. In what might be an echo of the preferences that helped our ancestors find ripe fruits, Spence told me, our modern brain still tends to link pinks and reds to sugar and yellows and greens to all things tart. Colors can play tricks too: When researchers artificially darken the tint of drinks or yogurt, study subjects insist that it tastes sweeter; when consumers see a rainbow of flavors in their snacks, the sheer appeal of variety may persuade some of them to eat more.

Some of artificial dyes’ biggest dangers, then, may not even be entirely inherent to the chemicals themselves. Foods that need a color boost tend to be the ones that experts already want us to avoid: candies, sodas, and packaged, processed snacks, especially those marketed to children, points out Lindsay Moyer, a CSPI nutritionist. Colors so exaggerated, so surprising, so unnatural inevitably tempt kids "to reach out of the grocery cart," Moyer told me. Dyes, once cooked up by us to mimic and juxtapose with the natural world, have long since altered us—manipulating our base instincts, warping our appetites—and transformed into a luxury that the world now seems entirely unable to quit.

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