Peppermint (Mentha ×piperita) is ahybrid species ofmint, a cross betweenwatermint andspearmint.[1] Indigenous to Europe and the Middle East,[2] the plant is now widely spread and cultivated in many regions of the world.[3] It is occasionally found in the wild with its parent species.[3][4]
Although the genusMentha comprises more than 25 species, the one in most common use is peppermint.[5] While Western peppermint is derived fromMentha × piperita, Chinese peppermint, orbohe, is derived from the fresh leaves ofM. haplocalyx.[6][7][8]M. × piperita andM. haplocalyx are both recognized as plant sources ofmenthol andmenthone, and are among the oldest herbs used for both culinary and medicinal products.[5][9]
Peppermint flowersAn 1887 illustration from Köhlers; Medicinal Plants
Peppermint was first identified in Hertfordshire, England, by a Dr. Eales, a discovery which John Ray published 1696 in the second edition of his bookSynopsis Methodica Stirpium Britannicarum. He initially gave it the nameMentha spicis brevioribus et habitioribus, foliis Mentha fusca, sapore fervido piperis and later in his 1704 volumeHistoria Plantarum he called itMentha palustris or Peper–Mint. The plant was then added to the LondonPharmacopoeia under the nameMentha piperitis sapore in 1721.[10][11][12][13]
It was given the nameMentha piperita in 1753 by Carl Linnaeus in hisSpecies Plantarum Volume 2.[14] Linnaeus treated peppermint as aspecies, but it is now universally agreed to be a hybrid betweenMentha viridis andMentha aquatica withMentha viridis itself also being a hybrid betweenMentha sylvestris andMentha rotundifolis.[15][16]
Peppermint is anherbaceous, rhizomatous,perennial plant that grows to be 30–90 cm (12–35 in) tall, with smooth stems, square in cross section. Therhizomes are wide-spreading and fleshy, and bear fibrousroots. Theleaves can be 4–9 cm (1+1⁄2–3+1⁄2 in) long and1.5–4 cm (1⁄2–1+1⁄2 in) broad. They are dark green with reddish veins, with an acute apex and coarsely toothed margins. The leaves and stems are usually slightly fuzzy. Theflowers are purple,6–8 mm (1⁄4–5⁄16 in) long, with a four-lobedcorolla about5 mm (3⁄16 in) diameter; they are produced in whorls (verticillasters) around the stem, forming thick, blunt spikes.
Flowering season lasts from mid- to late summer. Thechromosome number is variable, with 2n counts of 66, 72, 84, and 120 recorded.[17][18][19] Peppermint is a fast-growing plant, spreading quickly once it has sprouted.
Peppermint typically occurs in moist habitats, including stream sides and drainage ditches. Being a hybrid, it is usuallysterile, producing noseeds and reproducing onlyvegetatively, spreading by itsrunners.[4][19]
Outside of its native range, areas where peppermint was formerly grown for oil often have an abundance of feral plants, and it is consideredinvasive in Australia, theGalápagos Islands, New Zealand,[20] and the United States[21] in theGreat Lakes region, noted since 1843.[22]
Peppermint generally grows best in moist, shaded locations, and expands by underground rhizomes. Young shoots are taken from old stocks anddibbled into the ground about 0.5 m (1.5 ft) apart. They grow quickly and cover the ground with runners if it is permanently moist. For the home gardener, it is often grown in containers to restrict rapid spreading. It grows best with a good supply of water, without being water-logged, and planted in areas with partial sun to shade.
The leaves and flowering tops are used; they are collected as soon as the flowers begin to open and can be dried. The wild form of the plant is less suitable for this purpose, with cultivated plants having been selected for more and better oil content. They may be allowed to lie and wilt a little before distillation, or they may be taken directly to the still.
Severalcultivars have been selected for garden use:
Mentha ×piperita 'Candymint' has reddish stems.[23]
Mentha ×piperita 'Chocolate Mint'. Its flowers open from the bottom up; its flavour is reminiscent of the flavour inAndes Chocolate Mints, a popular confection.[24][25][26]
Mentha ×piperita 'Citrata' includes a number of varieties includingEau de Cologne mint,[27] grapefruit mint, lemon mint,[28] and orange mint. Its leaves are aromatic and hairless.
Mentha ×piperita 'Crispa' has wrinkled leaves.[29]
Verticillium wilt is a major constraint in peppermint cultivation. 'Todd's Mitcham', 'Refined Murray', 'Roberts Mitcham' (see above), and a few other cultivars have some degree ofresistance.[36]
Peppermint has a high menthol content. The essential oil also contains menthone and carboxyl esters, particularlymenthyl acetate.[40] Dried peppermint typically has 0.3–0.4% of volatile oil containing menthol (7–48%), menthone (20–46%), menthyl acetate (3–10%),menthofuran (1–17%), and 1,8-cineol (3–6%). Peppermint oil also contains small amounts of many additional compounds, includinglimonene,pulegone,caryophyllene, andpinene.[41]
Peppermint oil has a high concentration of natural pesticides, mainly pulegone (found mainly inM. arvensis var.piperascens (cornmint, field mint, or Japanese mint),[43] and to a lesser extent (6,530 ppm) inMentha ×piperita subsp.notho[44]) and menthone.[45] It is known to repel some pest insects, includingmosquitos,[46][47][48] and has uses in organic gardening[citation needed]. It is also widely used to repel rodents.[49]
Menthol activates cold-sensitiveTRPM8 receptors in the skin and mucosal tissues, and is the primary source of the cooling sensation that follows the topical application of peppermint oil.[56]
Candy canes are one of the most common peppermint-flavored candies.
Mentha ×piperita hybrid known as 'Chocolate Mint'
Freeze-dried leaves
Peppermint oil is also used in construction and plumbing to test for the tightness of pipes and disclose leaks by its odor.[57]
Medicinal uses of peppermint have not been approved as effective or safe by the USFood and Drug Administration.[58] With caution that the concentration of the peppermint constituent pulegone should not exceed 1% (140 mg), peppermint preparations are considered safe by theEuropean Medicines Agency when used in topical formulations for adult subjects.[59][60] Diluted peppermint essential oil is safe for oral intake when only a few drops are used.[53][59]
Although peppermint is commonly available as aherbal supplement, no established, consistent manufacturing standards exist for it, and some peppermint products may be contaminated with toxic metals or other substituted compounds.[58]Skin rashes, irritation, orallergic reactions may result from applying peppermint oil to the skin,[58] and its use on the face or chest of young children may cause side effects if the oil menthol is inhaled.[53][59] A common side effect from oral intake of peppermint oil or capsules isheartburn.[58] Oral use of peppermint products may haveadverse effects when used with iron supplements,cyclosporine, medicines for heart conditions or high blood pressure, or medicines to decrease stomach acid.[58]
^abMimica-Dukic, N.; Bozin, B. (2008). "Mentha L. species (Lamiaceae) as promising sources of bioactive secondary metabolites".Current Pharmaceutical Design.14 (29):3141–50.doi:10.2174/138161208786404245.ISSN1873-4286.PMID19075696.
^Dong, Wenjiang; Ni, Yongnian; Kokot, Serge (February 2015). "Differentiation of mint (Mentha haplocalyx Briq.) from different regions in China using gas and liquid chromatography".Journal of Separation Science.38 (3):402–9.doi:10.1002/jssc.201401130.ISSN1615-9314.PMID25431171.
^Bone, Kerry; Mills, Simon Y. (2013).Principles and practice of phytotherapy : modern herbal medicine (2nd ed.). Edinburgh: Churchill Livingstone.ISBN978-0-44306992-5.OCLC830314789.
^Ray, John (1696).Synopsis Methodica Stirpium Britannicarum. p. 234.
^Flückiger, Friedrich August (1874).Pharmacographia: A History of the Principal Drugs of Vegetable Origin, met with in Great Britain and British India. Macmillan. pp. 481–2.
^Harley, R. M. (1975).Mentha L. In:Stace, C. A., ed.Hybridization and the flora of the British Isles page 387.
^Wong, Warren (1972).The Changes that Occur in Peppermint Oil During Aging, Including the Relationship Between Changes in Chemical Composition and Flavor Characteristics. Ph.D. dissertation. Rutgers. p. 10.
^abcJullien, Frédéric; Diemer, Florence; Colson, Monique; Faure, Olivier (1998). "An optimising protocol for protoplast regeneration of three peppermint cultivars ( Mentha x piperita)".Plant Cell, Tissue and Organ Culture.54 (3):153–9.doi:10.1023/A:1006185103897.S2CID26626639.
^Dolzhenko, Yuliya; Bertea, Cinzia M.; Occhipinti, Andrea; Bossi, Simone; Maffei, Massimo E. (2010). "UV-B modulates the interplay between terpenoids and flavonoids in peppermint (Mentha ×piperita L.)".Journal of Photochemistry and Photobiology B: Biology.100 (2):67–75.doi:10.1016/j.jphotobiol.2010.05.003.hdl:2318/77560.PMID20627615.
^Khanna R, MacDonald JK, Levesque BG (July 2014). "Peppermint oil for the treatment of irritable bowel syndrome: a systematic review and meta-analysis".Journal of Clinical Gastroenterology.48 (6):505–12.doi:10.1097/MCG.0b013e3182a88357.PMID24100754.S2CID22520810.
^abcde"Peppermint oil". National Center for Complementary and Integrative Health, US National Institutes of Health, Bethesda, MD. 2016.Archived from the original on 5 July 2015. Retrieved13 July 2015.
^Popa, K.; Tykva, R.; Podracká, E.; Humelnicu, D. (3 June 2008). "226Ra translocation from soil to selected vegetation in the Crucea (Romania) uranium mining area".Journal of Radioanalytical and Nuclear Chemistry.278 (1): 211.doi:10.1007/s10967-007-7171-6.S2CID95563388.
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