The power of peppermint oil
Written by Robert Smith   
Wednesday, 03 July 2013
At the mention of peppermint, candy canes and ice cream comes to mind. But did you know that peppermint is also an age-old herbal medicine that has been used to treat a wide range of abdominal woes? The oil extracted from the peppermint plant contains a host of compounds, but the most abundant and perhaps the most pharmacologically important is menthol.

Studies have shown peppermint oil to be fairly effective at relieving irritable bowel syndrome (IBS), a collection of symptoms that includes abdominal pain and cramping, bloating, constipation and diarrhea that affects 5 to 20 percent of the population. One explanation is that the oil—especially the menthol—blocks calcium channels, which has the effect of relaxing the “smooth” muscles in the walls of the intestines.

Recently, Alex Ford, a McMaster University researcher, concluded that instead of popular over-the counter drugs, peppermint oil should be the first line of defense against IBS.

Peppermint can temporarily allay itching caused by insect bites, eczema and other lesions, including the rash of poison ivy. Peppermint tea can be used as a mouthwash for babies with thrush (yeast in the mouth) or for reducing nausea and vomiting during pregnancy, especially for women who want to avoid stronger medications.

Peppermint’s essential oil—menthol—is also an ingredient in many conventional over-the-counter products, including toothpaste, mouthwash, chewing gum, breath mints, chewing tobacco substitutes, cough lozenges and various muscle pain ointments.  Menthol stimulates the nerves that sense cold, creating that familiar cooling sensation, and inhibits those that react to painful stimuli, temporarily relieving the pain of muscles and organs that are cramped and in spasm. Your mouth also has some of these nerves, which is why products containing menthol "taste" cool. And, even though the effect doesn’t last long, sometimes even a brief reprieve from a hacking cough or aching muscle can work wonders.

Menthol has also been shown helpful in subduing many disease-producing bacteria, fungi and viruses, but because stronger antimicrobials are available, is usually not the first choice in treating serious infections. “Most of the (effective) species are really from the family Lamiaceae, or mint family,” Pavel Kloucek, a scientist at the Czech University of Life Sciences in Prague, told Discovery News. Kloucek and his team have recently identified two other mint family members—Mentha villosa and Faassen’s catnip—along with another non-mint herb, bluebeard, as also have bacteria-busting abilities. Moreover, essential oils for horseradish, garlic, hyssop, basil, marjoram, oregano, winter savory and three types of thyme also showed potent antimicrobial activity.

The researchers made the discovery while testing the essential oils to determine how well they could, in vapor form, kill the bacteria responsible for Listeria, Staph, E. coli, Salmonella infections, and more. They are hopeful that peppermint oil and others may soon be wafted in vapor form over food to inhibit bacterial growth. Plant essential oils are lipophilic, meaning that they gravitate towards fat, Kloucek explained. “And luckily, in the cell membrane of bacteria, there is plenty of fat, which serves as a seal. Essential oils are attracted to this fat and, as their molecules squeeze in between the fat molecules, they cause leakage of the membrane.” This leakage causes a meltdown that can eventually kill the bacteria.

The obvious problem to overcome in treating foods with essential oils to prevent illness is the oils’ potent taste. While strong mint flavor is desirable in a candy cane, it might not work well with other foods. According to Kloucek and his team, the solution is to carefully match the oil with the food. “To overcome unwanted flavors, an essential oil with the best scent best fitting to the taste of the treated product in the lowest possible concentration should be used,” he said. “You will probably not use garlic essential oil to treat grapes, but for some semi-finished meat products it can be suitable.” Kloucek’s findings have been accepted for publication in the journal Food Control.

Monique Lacroix, a professor at the INRS-Institute Armand-Frappier in Quebec, told Discovery News that she agrees “essential oils have a powerful antimicrobial property.” She particularly liked Kloucek’s study because it addressed the volatile nature of the oils by studying them in their vapor phase, as opposed to direct application.

Some researchers now advise consumers to eat a tablespoon or more of fresh peppermint, and other green herbs daily. A fun way to enjoy peppermint, aside from eating that leftover Christmas candy cane, is by placing peppermint leaves in an ice tray, and then filling the tray with cold water, pushing down any mint leaves that stick out. Put the tray in the freezer for several hours, and then add the peppermint ice cubes to a glass of water, sparkling water, or any other beverage that you enjoy having cold.