Medicinal Peppermint Oil (Mentha piperita): A Comprehensive Scientific Review

Description and Production

Tıbbi nane (Mentha piperita), su nanesi (Mentha aquatica) ve yeşil nane (Mentha spicata) arasında bir hibrit bitkidir. Nane yağı, bitkinin toprak üstü kısımlarından (yapraklar ve çiçekler) buhar distilasyonu yöntemiyle elde edilir. Bu yöntem, bitkinin uçucu bileşenlerini su buharı ile ayırarak konsantre bir yağ elde edilmesini sağlar. Elde edilen yağ, açık sarıdan renksize kadar değişen bir renkte olup, karakteristik keskin, nane kokusuna sahiptir. Kaliteli nane yağı, genellikle %100 saf ve terapötik dereceli olarak pazarlanır.

Biochemical Composition

The biochemical composition of medicinal peppermint oil is quite complex and may vary depending on the geography, climate, harvest time and distillation method. But the main components are usually the following:

• Mentol (%30-50): It is the main active ingredient of peppermint oil and gives the oil its characteristic cooling sensation and odor. It has analgesic (pain relieving), antispasmodic (muscle relaxant) and decongestant (decongestant) properties.
• Menthone (%10-30): It is a ketone derivative of menthol. It has a fresh, minty odor and may exhibit antimicrobial properties.
• 1,8-Cineole (Eucalyptol) (%3-10): It is an ingredient with airway-opening effects, helping to relieve the symptoms of coughs and colds.
• Isomenthone (%2-8): It is a component with a structure similar to Menthone, with a slightly minty odor.
• Menthyl Acetate (%2-10): It is the ester that contributes to the odor of peppermint oil.
• Pulegone (trace amounts): It is a ketone that can be found higher in some varieties of peppermint and can be toxic in high doses. It is usually found at low and safe levels in medicinal peppermint oil.
• Other components include terpenes such as limonene, pinene, germacrene D, beta-caryophyllene. These components give the oil unique aromatic and therapeutic properties.

Effects on bodily functions

The effects of medicinal peppermint oil on the body are supported by various scientific studies, especially its benefits on the digestive system:

1. Effects on the Digestive System (especially Irritable Bowel Syndrome - IBS): Peppermint oil is widely used in the management of digestive disorders thanks to its antispasmodic (muscle relaxant) properties. It is particularly effective in relieving symptoms of IBS (abdominal pain, bloating, gas, diarrhea or constipation). Menthol relaxes smooth muscles in the intestinal muscles, reducing cramping and pain.
   • Research Example: Several randomized controlled trials and meta-analyses have shown that enteric-coated peppermint oil supplementation significantly reduced IBS symptoms compared to placebo (Ford et al., 2018; Alammar et al., 2019). These studies support that peppermint oil is effective and safe in the management of IBS.
2. Headache and Migraine: Peppermint oil can help relieve headaches and migraines when applied topically. Menthol's muscle relaxant and analgesic properties can be effective for tension headaches.
   • Research Example: In a study by Gostner et al. (2000), a mixture of peppermint oil, eucalyptus oil and ethanol was found to provide pain relief in tension-type headaches compared to placebo.
3. Muscle Pain and Tension: When applied topically, peppermint oil can relieve muscle pain and tension. Its cooling effect creates a feeling of relaxation in the painful area.
4. Nausea and Vomiting: Peppermint oil is known to be effective in aromatherapy to relieve nausea. It can be especially helpful in post-operative nausea or nausea due to chemotherapy.
   • Research Example: Some small-scale studies on postoperative nausea and vomiting have shown that peppermint oil inhalation reduces symptoms (Tayebani et al., 2015).
5. Colds and Respiratory Diseases: Menthol has decongestant properties and can help relieve nasal congestion, making breathing easier. It can be used through steam inhalation.
6. Antimicrobial Effects: Peppermint oil can exhibit antibacterial, antiviral and antifungal properties thanks to its components (menthol, menthone).
   • Research Example: In vitro studies have revealed that peppermint oil shows activity against various bacterial (e.g. E. coli, Staphylococcus aureus) and fungal (e.g. Candida albicans) species (Iscan et al., 2002).
7. Anti-inflammatory Effects: Some research suggests that peppermint oil may modulate the inflammatory response. However, this effect is usually associated with topical or digestive effects and more research is needed on its overall effect on systemic inflammation.
   • Research Example: In animal studies, peppermint oil has been observed to reduce intestinal inflammation (Maheshwari et al., 2007).
8. Immune System: There is limited scientific evidence on the effects of peppermint oil directly on the immune system. However, its antimicrobial properties and overall inflammation-reducing effect may indirectly support the immune system.
9. Cardiovascular Health: There is insufficient scientific evidence of direct and significant effects of peppermint oil on cardiovascular health. Caution should be exercised due to concerns that some ingredients may have cardiac effects at high doses.
10. Physical Performance: Some athletes use peppermint oil before or during exercise for its cooling and airway-opening effects. This can help reduce perceived exertion and improve performance.
    • Research Example: A pilot study (Meamarbashi, 2014) suggested that inhaling peppermint oil may reduce perceived exertion and improve respiratory function during exercise. However, larger randomized controlled trials are needed in this area.
11. Reproductive Health: There is insufficient scientific evidence on the effects of peppermint oil on reproductive health. Care should be taken and a doctor should be consulted about its use during pregnancy and breastfeeding.

Areas of Use

Medicinal peppermint oil can be used in various ways:

• Aromatherapy It is used in diffusers or through steam inhalation to open the airways, relieve nausea, stimulate the mind or relieve stress.
• Topical Application: In diluted form, it is applied on the skin to relieve muscle aches, headaches, itching or tension. It is important to dilute with a carrier oil (almond oil, jojoba oil).
• Internal Use: It is used in the form of enteric-coated capsules, especially to relieve the symptoms of IBS. Taking pure essential oil directly orally is generally not recommended because it can irritate the mucosa.
• In the kitchen: Small amounts can be used to flavor food and beverages (but this use is not for medicinal purposes).

Side Effects and Dosage Information

Medicinal peppermint oil is generally considered safe when used correctly. However, some side effects may occur, especially in high doses or misuse:

Side Effects:

• Stomach Discomfort: Pure peppermint oil can cause heartburn, heartburn and nausea when taken directly orally. Enteric coated forms are therefore preferred.
• Allergic Reactions: Allergic reactions such as skin redness, itching or irritation may occur. A patch test on a small area of skin is recommended before use.
• Respiratory Problems: It may cause respiratory tract spasm in infants and young children. For this reason, peppermint oil should not be applied to the face or chest of young children.
• Drug Interactions: 
  • Antacids: They can cause heartburn by disrupting the coating of enteric-coated peppermint oil capsules.
  • Medicines that affect intestinal motility: Peppermint oil may interact with medicines that affect intestinal motility.
  • Drugs that reduce stomach acid: They can affect the capsule coating in the same way.
  • Cyclosporine It has been reported that peppermint oil may increase the absorption of cyclosporine.
• Other Situations: 
  • People with gallbladder disorders should use it with caution because it can affect the flow of bile.
  • It can worsen heartburn in people with gastroesophageal reflux disease (GERD).
  • Since there is insufficient safety data on its use in pregnant and lactating women, infants and young children, it should not be used without medical advice.

Dosage

• Enteric Coated Capsules (for IBS): Capsules containing 0.2-0.8 mL (about 187-200 mg) of peppermint oil are usually recommended 1-2 times a day, 30-60 minutes before meals. It is important to follow the manufacturer's instructions.
• Topical Application: It should be diluted %1-5 with a carrier oil (e.g. jojoba, almond or coconut oil). For example, 3-5 drops of peppermint oil can be added to 1 tablespoon of carrier oil.
• Aromatherapy A few drops can be added to a diffuser or 1-2 drops in hot water for vapor inhalation (avoid inhalation too close to the face).

It is important to consult a health professional before using peppermint oil for any medicinal purpose.

Storage Conditions

Since medicinal peppermint oil is a volatile oil, proper storage conditions are critical to preserve its quality and shelf life:

• Dark Colored Glass Bottles: Exposure to light can degrade the components of peppermint oil. It should therefore be stored in dark (amber or cobalt blue) glass bottles.
• Cool and Dry Environment: High temperatures and humidity cause the oil to spoil. Peppermint oil should be stored in a cool, dry place, away from direct sunlight and heat sources. Ideally, it can be stored in the refrigerator, which extends its shelf life.
• Tightly Closed Lid: Contact with air leads to oxidation and reduces the quality of the oil. The bottle cap should be tightly closed after each use.
• Out of the reach of children: It should be kept in a safe place out of the reach of children.

Conclusion and Future Research

Medicinal peppermint oil is a powerful herbal product scientifically proven to be particularly effective in relieving symptoms of irritable bowel syndrome and headaches/migraines. Its antispasmodic, analgesic and antimicrobial properties make it valuable in traditional and complementary medicine. However, caution should be exercised in its use, correct dosage and application methods should be followed, and a health professional should be consulted about its use, especially during pregnancy, breastfeeding and in young children. Future research should elucidate the mechanisms of action of peppermint oil in more depth, confirm its other potential therapeutic applications (e.g. neuropathic pain, cognitive function) with larger-scale human clinical trials, and provide more data on possible side effects and drug interactions.

Sources

• Alammar, N., Wang, L., Bieber, K., Khalid, A., & Mullin, G. E. (2019). The Impact of Peppermint Oil on Irritable Bowel Syndrome: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Journal of Clinical Gastroenterology, 53(9), 652-663.
• Ford, A. C., Moayyedi, P., Chey, W. D., Harris, L. A., Lacy, B. E., Saito, L., ... & Lembo, A. J. (2018). American College of Gastroenterology Monograph on the Management of Irritable Bowel Syndrome. The American Journal of Gastroenterology, 113(Suppl 2), 1-18.
• Gostner, P., Buzzi, M. G., & Colucci, R. (2000). The efficacy of a topical peppermint oil, eucalyptus oil, and ethanol preparation for the treatment of tension-type headache. Phytomedicine, 7(6), 461-464.
• Iscan, G., Kirimer, N., Kürkcüoğlu, M., Başer, K. H. C., & Demirci, F. (2002). Antimicrobial screening of Mentha piperita essential oil. Journal of Agricultural and Food Chemistry, 50(23), 6777-6779.
• Maheshwari, R. K., Indurwade, N. H., & Suryakar, V. K. (2007). Anti-inflammatory activity of topical peppermint oil on experimental animals. Indian Journal of Pharmacology, 39(5), 260.
• Meamarbashi, A. (2014). Physiological responses to peppermint ingestion before exercise. Avicenna Journal of Phytomedicine, 4(4), 282-286.
• Tayebani, S., Sharifi, S., & Ghassemi, R. (2015). The Effect of Inhaled Peppermint Essence on Postoperative Nausea and Vomiting After Cesarean Section. Journal of Complementary and Integrative Medicine, 12(3), 205-209.