Due to the insanely large volume of misinformation available on the properties of essential oils, it is my continuing mission to compile for you a list of facts for each oil. Presented below is my (ever-growing) list of the properties of peppermint oil, and the studies that support each claim.
As a young scientist, I know how hard sifting through and understanding
academic articles can be, so I endeavor to remove the jargon for you guys, making this research accessible to everyone. Because this information shouldn’t be limited to people who know words like antiplasmid and ambulatory (or those who have a crazy amount of free time to google each word).
Summary (to save your scrolling finger)
- Antibacterial, Antiplasmid
- Indigestion and IBS
- Focus and Energy
- Hunger Reduction
- Lice Treatment
- Side Effects and Cautions
Components of Peppermint Oil
Peppermint oil consists of: menthone (30.63 %), menthol (25.16 %), menthofuran (6.47 %), β-phellandrene (5.59 %), isomenthone (4.74 %), menthol acetate (4.61 %), pulegone (4.39 %), β-caryophyllene (3.05 %), neomenthol (2.83 %), 1,8-cineole (2.15 %). (1)
You’ll see the most familiar ingredients here are the menthone and the menthol especially. They are responsible for a large portion of the effects of peppermint oil, as discussed below.
Peppermint oil is effective as an antibacterial agent due to it’s main component, menthol (tested against E.Coli and Staph). Menthol is also shown to be an effective antiplasmid, meaning it can kill the DNA of the bacteria that gives it antibiotic resistance. (2) This means that peppermint oil can be effective against bacteria that have developed an antibiotic resistance (just how effective hasn’t been quantified yet), which is a growing problem in modern medicine. Menthol is also shown to be effective against biofilms commonly found on teeth in the mouths of humans. One study found it to be more effective than chlorhexidine, a common chemical found in mouthwashes. (3) This is why toothpastes are generally mint flavored; peppermint has been used throughout history to cleanse and whiten teeth.
[Update 10/21/15] This is also supported by this study, where antimicrobial activity was studied against oral pathogens. They concluded that peppermint could be used effectively as antiseptic solution against oral pathogens studied (Staphylococcus aureus, Enterococcus fecalis, Escherichia coli, and Candida albicans).
Indigestion and IBS
Peppermint oil shows promise as an effective combatant of indigestion and semi-effective in the case of irritable bowl syndrome (IBS). A combination of 90mg peppermint oil and 50mg caraway oil taken internally was shown to have a statistically significant effect of reducing indigestion when taken twice a day for 29 days. (4) However, results are still inconclusive for IBS. While the main components of peppermint oil are found in many over-the-counter remedies for IBS, there is still not enough information to conclude one way or the other about the effectiveness of the oil. (5)
A 2001 study shows that peppermint oil is effective at inhibiting the histamine reaction in rats. (i.e. it acts as an antihistamine) (6) This could extend to the reduction of allergic symptoms such as congestion.
Focus and Energy
In a study objectively exploring the effectiveness of peppermint oil at reducing daytime sleepiness in participants placed in a normally sleep-inducing environment, the oil was shown to reduce daytime sleepiness. However, the mechanism is not fully understood. (7) In addition, the inhalation of peppermint oil was shown to increase ambulatory activity in mice (meaning they moved around more). This study is part of a larger ongoing study working to explain the behavioral effects of the oil. (8)
While keeping you awake, peppermint oil is also found to improve focus. According to a 2008 study, participants exposed to peppermint oil had improved memory and processing speeds, as compared to a control group. It was also found to increase their sense of calm. Their mental agility was measured using a series of tests called the Cognitive Drug Research computerized assessment battery, and mood was assessed before and after on a mood scale. (9)
Peppermint oil inhalation was shown to reduce feelings of hunger and total caloric intake over a 5 day period, vs. non inhalation. Participants were all their own controls, meaning they spent 5 days inhaling peppermint oil and recording their diet, and 5 days recording without peppermint oil. All participants reported a reduction in feelings of hunger, and their caloric intake, measured overall and by type, was reduced. Most notably, fat and sugar caloric consumption decreased. (10)
Several essential oils, including peppermint, were tested for their toxicity to lice and lice eggs. It was found that peppermint oil, when dissolved in 40% ethanol (to a concentration of 1%), is 100% effective at killing lice when exposed to lice in the lab for 17h. It is also 82.4% effective at killing lice eggs when followed by an oil/vinegar/water rinse (2 drops oil, 47.5mL vinegar, 47.5mL water). (11)
Side Effects and Cautions
An overdose of peppermint is shown to have the following effects: (12)
- Skin rashes
- Slow or rapid breathing
- Abdominal pain and diarrhea
- Vomiting and nausea
- Urinary problems
The following list of people should use extra caution when using peppermint oil:
- Pregnant and Nursing Women: Peppermint oil has been shown to reduce milk production. (13)
- Infants and children under seven: never use undiluted essential oils.
- Diabetics: There is a study that shows that peppermint oil may increase the risk of low blood sugar. (14)
- Those with gastroesophageal reflux disease (GERD) and hiatal hernia (15)
- Those with gallbladder problems: peppermint oil may cause inflammation of the gallbladder. (16)
- Anyone taking antacids: these drugs can interact with peppermint oil, increasing the risk of heartburn. (17)
Also keep in mind that an individual may have an allergic reaction to any oil, so always use caution when using a new oil. Also remember to always dilute your oils! Read more about that here.
This list is obviously not comprehensive, so stay tuned for updates as I discover more sources of information. If you guys know of other uses or research, let me know in the comments below!
These statements have not been evaluated by the Food and Drug Administration. Essential oils are not intended to diagnose, treat, cure, or prevent any disease.
References:1. Journal of Essential Oil Bearing Plants, 2013;16(4):506-512
2. Zsuzsanna Schelz, Joseph Molnar, Judit Hohmann, Antimicrobial and antiplasmid activities of essential oils, Fitoterapia, Volume 77, Issue 4, June 2006, Pages 279-285, ISSN 0367-326X
3. Iraj Rasooli, Shojaedin Shayegh, Massoud Taghizadeh, Shakiba Darvish Alipoor Astaneh. Phytotherapeutic prevention of dental biofilm formation. Phytother Res. 2008 Sep;22(9):1162-7. PMID: 18729251
4. Alimentary Pharmacology and Therapeutics. 2000 December;14(12):1671-7
5. Pittler MH, Ernst E. Peppermint oil for irritable bowel syndrome: a critical review and metaanalysis. Am J Gastroenterol 1998;93: 1131–5.
6. Inoue T, Sugimoto Y, Masuda H, et al: Effect of peppermint (Mentha piperita L.) extracts on experimental allergic rhinitis in rats. Biol Pharm Bull 24: 92–95, 2001.
7. Mark Ian Keith Norrish and Katie Louise Dwyer. Preliminary investigation of the effect of peppermint oil on an objective measure of daytime sleepiness. International Journal of Psychophysiology. 55 (2005) 291– 298.
8. Toyoshi Umezu, Akiko Sakata and Hiroyasu Ito. Ambulation- promoting effect of peppermint oil and identification of its active constituents. Pharmacology, Biochemistry and Behavior 69 (2001) 383–390.
9. Moss M1, Hewitt S, Moss L, Wesnes K. Modulation of cognitive performance and mood by aromas of peppermint and ylang-ylang. Int. J. Neuroscience, 2008. 18(1):59-77.
10. J. A. Reed et al. Effects of peppermint scent on appetite control and caloric intake. Appetite. (2008), doi:10.1016/ j.appet.2008.04.196.
11. Lowana Veal. The potential effectiveness of essential oils as a treatment for head lice Pediculus humanus capitis. Complementary Therapies in Nursing & Midwifery. (I 996) 2, 97-101.
12. Asian Journal of Pharmaceutical and Clinical Research, A Review on Peppermint Oil
13. New Beginnings, 2009;29(5-6):38-40