How Your Toothpaste Gets So Minty Fresh

“When we get really close to harvest, you can smell the mint everywhere,” says Kimberley Schutte-Freeman, a second-generation mint farmer in Othello, Washington. “It just fills the air. You can smell it for miles, driving by. It smells like you just brushed your teeth.”

Schutte-Freeman and her family grow and distill mint essential oils in the Columbia River basin, one of the most important mint-farming regions in the Pacific Northwest, the heartland of America’s mint industry. And it’s no surprise that Schutte-Freeman would connect the fragrance of mint to the smell of toothpaste. Her farm is one of the more than 200 family farms that supply Colgate-Palmolive, the top buyer of US-grown mint oil.

US mint growers and the oral care industry are deeply intertwined. According to the Mint Industry Research Council, forty-five percent of American mint oil is used to flavor toothpaste, mouthwash, and other oral hygiene products. (Another forty-five percent goes into chewing gum.) Stroll down the dental aisle at any pharmacy or supermarket — the overwhelming majority of products feature mint flavors. There are some outliers – bubblegum toothpaste for kids, fennel for gourmandizers and the menthol-averse – but mint rules the category. A minty mouth is a clean mouth; breath isn’t fresh unless it’s minty-fresh.

In an era when so many familiar products – from Oreos to seltzer to yogurt – have rolled out new flavor experiences, why have Americans stuck with mint for their toothpaste and mouthwash? What’s the history behind this powerful union of mintiness and dental hygiene?

Toothpaste itself has been around for millennia. Abrasive tooth-cleaning powders – made from substances such as burnt snail shells, ground bones, and pumice – were available in ancient Egypt, Persia, China and the Greco-Roman empire. These were sometimes flavored with roots, seeds, and herbs, including mint. But mint was not the dominant flavor, and there’s little evidence that these preparations were routinely used.

At the beginning of the 1800s, toothbrushing was still uncommon – certainly not a daily habit. This would change with the industrialization of food production.  A proliferation of softer, sweeter foods made the mouths of modern eaters into caverns of decay. Sure, cavities and gingivitis troubled our paleo forebears, but nothing like the plague of rotten and missing teeth that afflicted the first generations to consume processed foods sweetened with commodity sugar. More men were rejected from the US draft for “defective and deficient” teeth than any other cause during both world wars. A 1920s survey found that more than 98 percent of University of Minnesota freshmen had cavities. “Tooth decay, then, was as much a product of the second industrial revolution as were processes of mass production, distribution, and consumption,” writes Peter Miskell, a business historian at the University of Reading in the UK.

If the new consumer economy created the problem, it also delivered the solution: dentifrice.  Colgate & Co. – then a New York-based soap and candle company — introduced the first mass-produced tooth-powder in the early 1870s. (It came in a jar; the now-standard squeezable tube of creamy paste wouldn’t appear until the 1890s.) Other brands – including Kolynos, Pepsodent, and Ipana – soon followed.  By the beginning of the twentieth century, many of these companies were flavoring their toothpastes and -powders with peppermint and spearmint oils.   

Why mint? US farmers had been growing and distilling mint oil since colonial times, largely for therapeutic and pharmaceutical uses. Toothpastes, introduced as new kinds of hygienic products, were an extension of this market. And then there’s the unique sensation mint provides. Peppermint oil contains menthol. Menthol smells “minty,” but its effect is more than just aromatic. It also triggers sense receptors in your mouth and on your skin that respond to cold temperatures, producing a chilling, slightly numbing sensation, a chemical simulacrum of coolness.

In the first half of the twentieth century, advertising turned toothbrushing into a social necessity, alerting Americans to the horrors of filmy, yellowing teeth, and (shudder!) halitosis. If you wanted to avoid the disgust and rejection of your friends, colleagues, and loved ones, you’d best brush your teeth every single day. Menthol’s sensory cue, that burst of minty coolness, was how you knew it was working — a sign of effectiveness that was also a badge of social acceptability.   

But until the 1950s, that minty clean feeling was mostly just a feeling. There was little evidence that toothpaste actually did what it promised: prevent cavities and improve oral health. It was not until 1955, when Proctor & Gamble added stannous fluoride to its Crest-brand toothpaste – after a decade of dental research at the University of Indiana – that toothpaste could claim to be clinically proven to combat decay. Other manufacturers soon followed suit, adding fluoride and other scientifically proven ingredients to fight against cavities, gum disease, and tartar.   

The ADA-endorsed compounds that makes today’s toothpaste and mouthwash effective also add sensations — usually not very pleasant ones. Fluoride imparts a sharp, metallic tang.  Tetra-sodium pyrophosphate, a tartar-control agent, has a bitter, burning taste. Other key ingredients can taste astringent, chalky, and generally icky.

Making a toothpaste pleasantly minty, then, requires more than simply adding mint to the mix. It requires the specialized skills of a flavorist, an expert trained in the design and development of flavors.   

Bob Vogt is a senior flavorist at Colgate, where he has spent nearly two decades developing flavors for products such as Colgate Total (“a peppermint-dominant flavor with some sweet characteristics and a lingering coolness,” as he describes it) and Tom’s of Maine (Colgate’s all-natural brand).   

Just as a master distiller blends different whiskies to achieve a consistent product, Vogt’s task is to combine different essential oils into a blend that reproduces a familiar flavor profile and masks the off-flavors inherent to the other ingredients in toothpaste or mouthwash. For products like Colgate Total, this can include using flavor modifiers (to reduce bitterness, for instance, or enhance the cooling sensation).

North American mint oil, he says, is critical to his work as a flavorist. And he and others in the industry are aware that in order to maintain the supply of this essential material, companies must partner with farmers to encourage them to continue growing. In the decade beginning in the late 1990s, the number of farms in the US growing mint dropped precipitously — from almost 1,000 in 1997 to around 350 in 2007 — due in part to competition from cheaper, foreign-grown options, especially Indian cornmint oil (Mentha arvensis). Cornmint oil has a high menthol content —70 percent or more by volume, versus the 40 percent typical in peppermint (Mentha piperata). (Spearmint (Mentha spicata) contains only negligible levels of menthol).

But flavorists like Vogt know that mint flavor is more than just menthol. While lower-priced cornmint oil is typically used to impart a generalized mintiness, US-grown mint oils are designated by growing region and blended to achieve distinct nuances and top notes.

 “There are regional differences similar to what you’d find in wine,” Vogt explains. Peppermint grown in Oregon’s Willamette Valley typically has a light, sweet, clean flavor; peppermint from Yakima, Washington tends to taste more pungent and herbaceous. Idaho’s peppermint is known for its particularly peppery kick. The precise qualities of these oils varies from harvest to harvest. Essential oil brokers and companies like Colgate use analytic tools like gas chromatography as well as sensory panels to carefully evaluate the properties of each oil.

Few, if any, US farmers farm only mint. The dark-green fields of peppermint, and the sprightlier, brighter green of spearmint, are rotated with crops like alfalfa, potatoes, seed crops, sweet corn. And there’s always a risk that the small-to-medium size farms that tend to grow mint may turn to other less labor-intensive, more profitable ventures. “One of the big competitive crops we’re losing land to is hazelnut trees,” says Vogt. “Some of those areas in Oregon and Washington, farmers are replacing their mint fields with hazelnuts. We want to make sure that farmers will continue to see the rewards in growing mint.”

Steve Salisbury, research and regulatory coordinator for the Mint Industry Research Council (MIRC), directs efforts to support US mint farmers. One issue of ongoing concern is verticillium wilt, a difficult-to-eradicate fungal pathogen that can decimate peppermint productivity; once a plot of land is infected with wilt, mint can no longer be grown there. MIRC is funding research into new cultivars, in hopes of producing a wilt-resistant plant. MIRC also invests in sustainability initiatives — to reduce the energy requirements of steam distillation, for instance, or improve irrigation methods to minimize water use. “We’re getting really efficient with how we use water to produce our crops,” Salisbury says.

“North American mint oil is considered the global standard,” Salisbury says. “And we’re keeping it that way.”

I ask Catalina Lee, head of global flavors and fragrances at Colgate-Palmolive’s oral care division, whether the rest of the world share’s US consumers’ predilections for minty-fresh toothpaste and mouthwash. Indian consumers, she told me, “like spicy notes, with a lot of clove.” Chinese consumers enjoy “tea and floral-type flavors.” In Latin America, “citrus-type flavors, with some exotic cues like lemon and lime” are popular. “But always,” Lee notes, “mint will be present in these flavors,” as a bass-note or a backdrop, providing that distinctive sensation, that bloom of brisk coolness, that flavor of clean.   

“People sometimes don’t realize that the mint in their toothpaste comes from a farm,” Schutte-Freeman says. She admits she didn’t used to think about it much, either, until her farm started partnering with Colgate. “Now when I brush my teeth I wonder, ‘is any of our mint in this?

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