Everything you need to know about peppermint essential oil

Thepeppermint essential oil is a natural oil. It comes from a variety of mint known as mentha x piperita. Peppermint essential oil is typically extracted from the leaves of the plant through steam distillation. This process allows for the production of a pure oil, concentrated in active ingredients. Peppermint was already used in ancient times for its medicinal properties and pleasant aroma. Indeed, it has a characteristic fresh and herbaceous smell that is reminiscent of mint.

Today, peppermint essential oil is widely available and appreciated for its numerous beneficial properties. Its uses are diverse: it is used in aromatherapy, alternative medicine, cosmetics, and in many household products.

Peppermint essential oil is obtained through steam distillation or hydrodistillation. This is a heat extraction method that requires the use of a still, a device designed for the separation of products by heating. Here are the necessary steps for extracting peppermint essential oil:

1. The leaves of Mentha x piperita are harvested at the onset of flowering as this is the period when the content of essential oils is at its maximum.

2. They are dried for several days to remove the maximum amount of water.

3. The dried leaves are introduced into a still.

4. The entirety is heated until steam is formed. This steam is concentrated into essential oil, which is highly volatile, and water.

5. The steam is then cooled. Through condensation, facilitated by a refrigerant, it reverts back to a liquid state and due to the differing densities of water and oil, which prevent them from mixing, the two elements separate.

6. The essential oil of peppermint is harvested and packaged for use.

The essential oil of peppermint boasts numerous skin and hair benefits. These include:

• Anti-inflammatory.

  Peppermint essential oil is composed of two ingredients, menthol and menthone, which are responsible for its anti-inflammatory activity. The menthol contained in the'peppermint essential oil inhibits the production of inflammatory molecules such as prostaglandin PGE-2, interleukin-IL-1-β and leukotriene LTB-4. It can also block calcium channels involved in the production of cytokines and the transmission of pain signals. This has the effect of reducing the sensation of heat and the pain that can be generated by the inflammatory reaction. Menthone, another compound of peppermint essential oil, has significantly inhibited the release of pro-inflammatory cytokines, including TNF-α, IL-1β and IL-6.

  By inhibiting these pro-inflammatory cytokines, rosemary essential oil helps to reduce inflammation and can therefore be beneficial in alleviating symptoms associated with skin conditions such asacne or soothing the scalp.

• Antibacterial:

  Several studies have analysed the antibacterial power of peppermint essential oil. One study demonstrated that menthol has significant antibacterial activity against both Gram - and Gram + bacteria. The mechanism behind this action is not yet fully understood, but it is hypothesised that menthol, present in the essential oil, disrupts the lipid fraction of the bacterial plasma membrane. This results in an alteration of the membrane's permeability, leading to a leakage of essential materials within the cell.

  This property requires further research for a more in-depth understanding of its mode of action. However, it shows promising potential for the treatment of certain bacterial skin conditions.

• Antifungal:

  Some of the active substances present in the formulation of peppermint essential oil possess antifungal properties. A study has revealed that menthol and menthone, when acting together, have a synergistic fungicidal action against Rhizopus and Mucor, while significantly suppressing the growth of Sclerotinia. These compounds act by disrupting the cellular membrane of the fungi, altering their structure and causing a leakage of essential substances, which ultimately leads to the death of the fungal cells.

  The antifungal properties of peppermint essential oil could be particularly useful in the treatment of skin issues such as dandruff. However, to confirm their specific effectiveness against the fungi responsible for these conditions, further studies are necessary.

• Antiviral:

  According to a study, peppermint essential oil could potentially possess antiviral activity due to the presence of menthol in its composition. This antiviral property was observed in cells infected with the herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). To inhibit 50% of the formation of herpes simplex virus plaques, concentrations of peppermint essential oil of 0.002% for HSV-1 and 0.0008% for HSV-2 were required. However, the exact mechanism of action behind this antiviral activity has not been clearly elucidated in the context of this study.

• Stimulates hair growth :

  A study has revealed that the topical application of peppermint essential oil for 4 weeks, at a concentration of 3%, stimulated the growth of thick and long hair. The research observed an elongation of hair follicles, from the epidermis to the subcutis, which was associated with an increase in the length of the keratinised hair shaft. This extension of the follicles is a positive indicator of hair health and growth. The study also noted that peppermint essential oil significantly increased the mRNA expression of the IGF-1 gene. This gene plays a mitogenic role by promoting the growth and survival of cells, which contributes to hair thickening. Furthermore, peppermint essential oil encourages the early transition of hair into the growth phase (anagen phase) by stimulating the dermal papilla and an enzyme called alkaline phosphatase.

When used appropriately and correctly dosed, this essential oil is generally considered safe. However, it is important to highlight that peppermint essential oil can become toxic and pose a health risk in cases of overdose or improper use.

When applied topically, peppermint essential oil can cause irritations and burns due to its high menthol content. These reactions can occur when the essential oil is applied directly to the skin or scalp without being previously diluted with another oil. It is recommended to dilute it at a rate of 10 to 15% to avoid any issues. Allergic reactions are rare with this essential oil as it contains low amounts of allergenic compounds such as limonene (≤ 5%) and linalool (≤ 5%). However, to avoid any risk, it is recommended to always perform a preliminary test on a small area of the skin before using a product containing peppermint essential oil. To do this, apply a small amount in the crook of your elbow, wait 24 hours, and check if there is no pain or itching.

This essential oil exhibits neurotoxicity due to its high concentration of menthol, menthone, and isomenthone, all of which are neurotoxic and abortifacient compounds. As a result, it is strongly advised against using this essential oil during pregnancy due to its abortive properties and the possibility of neurotoxic effects. Similarly, it is not recommended for breastfeeding women and children under 6 years of age due to their increased sensitivity to these potentially harmful substances. Furthermore, it is essential that anyone suffering from a disease consult a doctor before taking peppermint essential oil, as it could interfere with certain treatments.

Peppermint essential oil can be utilised in three distinct ways. When applied topically, this essential oil should be diluted at a rate of 10 to 15% in another vegetable oil such as the argan oil or the avocado oil for instance. For children, it is recommended to dilute it to a level of 5% as their skin is more sensitive than that of an adult. Peppermint essential oil can also be used orally, particularly to aid in cases of nausea, vomiting or motion sickness. Thanks to its high concentration of menthol, its minty aroma can also be beneficial in combating bad breath. However, caution should be exercised when using this oil orally and medical advice should be sought. The intake of this oil should not exceed 3 drops per day. Through inhalation, peppermint essential oil, with its refreshing effect, is beneficial for clearing the nose by thinning the mucus, which facilitates its flow. For this, place 1 to 2 drops of peppermint essential oil on a handkerchief, keeping it a few centimetres away from your nose, then breathe in.

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KEHILI S. & al. Peppermint (Mentha piperita L.) essential oil as a potent anti-inflammatory, wound healing and anti-nociceptive drug. European Journal of Biological Research (2020).

CHEN X. & al. A Natural Plant Ingredient, Menthone, Regulates T Cell Subtypes and Lowers Pro-inflammatory Cytokines of Rheumatoid Arthritis. Journal of Natural Products (2022).