Peppermint

Mentha × piperita

Family: Lamiaceae Part used: Leaves

Key Compounds

• Menthol
• Menthone
• Menthyl acetate
• Menthofuran
• 1,8-Cineole
• Rosmarinic acid
• Luteolin

Traditional Use

• Roman flavouring — mint used in sauces, wine, and as garlands, documented by Pliny the Elder, c.79 CE
• Medieval European monastery herb gardens — mint cultivation for medicinal and culinary use
• Commercial cultivation in Mitcham, Surrey from the 18th century — 'Mitcham peppermint' quality standard
• Hokkaido menthol production — Japanese Mentha arvensis supplied 70% of global natural menthol in the 1930s
• Global confectionery, pharmaceutical, and oral hygiene industries from the 19th century onward

Peppermint does not cool you down. Menthol — the compound responsible for that sensation — works by tricking a nerve receptor that normally detects cold temperatures. The receptor cannot tell the difference between menthol and actual cold. Your nervous system reports “cold” to your brain. Nothing has changed temperature. This works in hot drinks. It works on a 35°C day. The coolness is entirely fabricated.

This is probably the most commercially exploited neurological illusion produced by any plant on earth.

Peppermint is in your toothpaste, your chewing gum, your throat lozenges, your digestive tablets, your mouthwash, possibly your shampoo, and a number of pharmaceutical preparations. Global peppermint oil production runs to thousands of tonnes per year. It is the most-produced essential oil in the world by volume. All of this is built on one receptor that cannot tell menthol from cold.

Meet the plant

Peppermint cannot reproduce from seed. It is a sterile hybrid — the original was a chance cross between watermint and spearmint, found in Hertfordshire in 1696. Every peppermint plant that has ever existed since then is a division of something else’s roots. There is no wild peppermint waiting to evolve somewhere. This is the only peppermint that exists, cloned continuously for three hundred years.

The plant uses this situation to compensate. It spreads by underground rhizomes and will colonise an entire garden bed if given the opportunity. Square stems, dark green serrated leaves, faint reddish tinge to the stem. Hold a leaf to light and you can see the oil glands — tiny clear dots distributed through the tissue, which is exactly what it looks like when a plant is producing its own neurological weapons.

2,000 years of mint — and one menthol empire that used to be in Hokkaido

Pliny the Elder documented Romans using mint in garlands, sauces, and wine around 79 CE. Greek mythology gave the whole genus its name: the nymph Minthe was transformed into the mint plant by a jealous goddess, and the genus Mentha remembers her. This is how botanical naming went before Linnaeus arrived to impose order.

Peppermint as a distinct hybrid was first formally described in 1696, found growing wild in Hertfordshire. Within a century it was a commercial crop in Mitcham, Surrey — the same town known for lavender — and “Mitcham peppermint oil” became a quality standard. Mitcham’s reputation for producing things and naming them after itself was apparently well established.

The Japanese connection is through a different species entirely. Mentha arvensis var. piperascens — ハッカ, Japanese field mint — was commercially cultivated in Hokkaido from the Meiji era. By the 1930s, Kitami in eastern Hokkaido supplied approximately 70% of global natural menthol. The entire world’s toothpaste, throat sweets, and menthol cigarettes ran on one prefecture in northern Japan. WWII disrupted trade, synthetic menthol followed, and the industry shrank. Small-scale ハッカ production continues in Kitami as a regional specialty, which is a very dignified way to finish a story that once ran the world’s toothpaste supply.

The chemistry

One compound does almost everything: menthol. At 35–55% of the essential oil, it is responsible for the smell, the sharpness, the commercial value, and the cooling sensation that is not actually cold.

The mechanism: menthol binds to the TRPM8 receptor, a cold-sensing ion channel in nerve cells. The receptor cannot tell the difference between menthol and actual cold. When it fires, your brain registers “cold.” No temperature change occurs. None. The menthol in cigarettes makes harsh smoke feel smoother by the same mechanism — a darker application of the same trick. The plant invented a neurological illusion. Humans have been finding new things to do with it for a hundred years.

Menthofuran, also present in the oil, is worth noting: it is used as a quality defect marker. Too much means poor distillation or the wrong variety. The industry tests for it because at high levels it becomes a liability, not an asset. The plant has opinions about how it should be processed. The plant’s opinions are correct.

What people actually do with it

As a tea, peppermint is one of the most accessible herbal teas in the world — sharp, clean, slightly cooling, drinkable by almost everyone. Steep five minutes, covered, then stop. Longer and it goes bitter with no way back. The lid keeps the aromatic compounds in the cup rather than your kitchen ceiling. In Japan, peppermint tea bags are in every supermarket and convenience store. It is usually the first herbal tea a Japanese household actually buys.

The mint flavour in toothpaste, mouthwash, chewing gum, hard candy, throat lozenges, cough drops, pharmaceutical tablets, and most respiratory sprays is peppermint or synthetic menthol derived from it. When something labelled “mint” tastes sharp and cooling rather than soft and sweet, that is peppermint. Spearmint is the gentle one. Peppermint took over the industrial market in the 19th century and has not reconsidered.

Topically, diluted peppermint oil on the temples is a traditional headache remedy. The TRPM8 mechanism means the cooling sensation is real and measurable — you will feel something, definitively, regardless of whether it helps the headache. The plant is good at making you feel something. What you do with that is your business.

Could you grow this yourself?

Yes, and it will make decisions you didn’t approve.

Peppermint wants moist, fertile soil and consistent water. It tolerates partial shade. It does not want to dry out. These are reasonable preferences. The issue is underground: peppermint spreads by rhizomes, and an uncontained plant will colonise an entire garden bed in two seasons. This is not a metaphor. Grow it in a container, or bury a container in the ground, or install a root barrier. The plant has views about where it should be and the ambition to act on them.

In most of Honshu and Hokkaido, it is fully perennial — dies back in winter, returns from the roots in spring. Harvest any time during the growing season. Most intense flavour just before or at the beginning of flowering, July–September.

Peppermint and ハッカ in Japan

Japan’s connection to mint is real and specific, but it involves ハッカ (Mentha arvensis var. piperascens, Japanese field mint) rather than peppermint. Commercially cultivated in Hokkaido from the Meiji era, Kitami’s ハッカ fields supplied approximately 70% of global natural menthol in the 1930s. The world’s toothpaste ran on Hokkaido. WWII disrupted the trade routes, synthetic menthol arrived and was cheaper, and the industry shrank to a regional specialty.

ハッカ油 is still sold in Hokkaido: insect repellent, cooling spray, aromatherapy item, souvenir with genuine historical roots. The history is on every label without being stated directly.

Western ペパーミント is everywhere: tea bags in every supermarket, essential oil in pharmacies, extract in chocolate and confectionery. The word ミント functions as a general flavour category in Japanese consumer culture — ミント味 covers everything from peppermint tea to toothpaste to mints after a meal. Three centuries of a plant that can’t reproduce from seed, and it is now a category in a language it has never heard.

Things you’re probably wondering

Why does peppermint feel cold? Menthol activates the TRPM8 receptor — the same nerve receptor that responds to cold temperatures. This creates an identical neural signal to cold without any actual temperature change. Mint in a hot drink still feels cooling because your nervous system is receiving a ‘cold’ signal regardless of the actual temperature.

What is peppermint used for? Peppermint (Mentha × piperita) is used as a herbal tea, in confectionery (gum, mints, chocolate), in oral hygiene products (toothpaste, mouthwash), in pharmaceutical preparations, and as an essential oil for aromatherapy and cooking. In Japan it is sold widely as tea bags, as ハッカ (Hokkaido mint) products, and as an ingredient in skincare and haircare products.

What is the difference between peppermint and spearmint? Peppermint (Mentha × piperita) is a hybrid that contains high menthol — the compound responsible for intense cooling. Spearmint (M. spicata) contains mostly carvone, which gives a sweeter, less intense mint flavour with much less cooling. Peppermint is what you taste in toothpaste; spearmint is what you taste in most chewing gum.

Where is peppermint grown in Japan? Peppermint as such (M. × piperita) is not commercially cultivated at scale in Japan. However, Mentha arvensis (ハッカ, Japanese field mint) has a long history of commercial cultivation in Hokkaido, particularly in Kitami city. In the 1930s, Hokkaido’s M. arvensis supplied approximately 70% of global natural menthol. Small-scale ハッカ production continues as a Hokkaido specialty.

Can you grow peppermint at home in Japan? Yes — peppermint is easy to grow in Japan. It needs moist, fertile soil and consistent watering. It will grow in partial shade, unlike lavender. The critical rule: grow it in a container or with a buried root barrier, because it spreads aggressively underground via rhizomes and will take over a garden bed. In most of Japan, it overwinters well and comes back each spring.

Botanical details

The full compound list

See Also

• Spearmint — the other parent species; sweeter, less intense
• Lemon balm — also Lamiaceae; different but similarly accessible tea herb
• Thyme — Lamiaceae family; shared aromatic European tradition

References

• McKay, D.L. & Blumberg, J.B. (2006). A review of the bioactivity and potential health benefits of peppermint tea. Phytotherapy Research, 20(8), 619–633.
• Eccles, R. (1994). Menthol and related cooling compounds. Journal of Pharmacy and Pharmacology, 46(8), 618–630.
• European Medicines Agency (2008). Assessment report on Mentha × piperita L., folium. EMA/HMPC/522409/2008.
• Lawrence, B.M. (2007). Mint: The Genus Mentha. CRC Press.
• Hokkaido Prefectural Government. Historical records of Mentha arvensis cultivation in Kitami region.