Spearmint History and Traditional Uses

    The first recorded use of Mentha spicata dates as far back as 400 BC (Hanrahan, 2001). A native species to the mediterranean region, spearmint was collected throughout the Roman empire and valued for its pleasant aroma (Hanrahan, 2001). In ancient times, spearmint was used to clear unpleasant odours, freshen breath, and protect food stores from rodents, but there is little indication that it was used medicinally at this time.

    As the Roman empire grew, the spearmint was brought to Britain where its  medicinal properties became recognized (Hanrahan, 2001). Its primary medicinal use was to treat indigestion, nausea and vomiting, as well as relieve the symptoms of respiratory illnesses such as bronchitis and the common cold (Kunnumakkara, 2009). Administered in the form of tea made from dried spearmint leaves, its mild nature made it popular for use in young children (Hanrahan, 2001). In the middle ages, spearmint was also used as treatment if you were bit by a wild dog. The fresh herb was mixed with salt and applied directly to the wound to promote healing (Hanrahan, 2001).

    
  During the colonial era, the British brought spearmint with them to North America, where it now grows wild throughout southern parts of Canada and much of the United States (Natural Standard, 2010).  In 1893, Wrigley Incorporated transformed the way spearmint was used in North America by introducing it as a breath freshening gum (video 1;Wrigley, 2010). Though this is the most common use for Mentha spicata today, the medicinal properties of spearmint have not been forgotten.

Video 1: Spearmint Gum Commercial 1950s

Today, spearmint is most commonly used in breath freshening products such as gum, mouthwash, and toothpaste

Changes in Wrigley's spearmint gum over time

Spearmint's Active Components and Preparation

Figure 1b: Carvone

Figure 1a: Menthol

The two principle constituents of spearmint are carvone and menthol (figure 1), along with 29 other supporting compounds, the medicinal of which are still unknown (Kunnumakkara, 2009). Carvone has been shown to have antibacterial capabilities, as well as act as an acetylcholinesterase inhibitor to increase serum levels of acetylcholine (Rafii, 2007; Adsersen, 2006). Menthol has been shown to have anesthetic properties, with significant reduction of pain  through a decrease in peripheral nerve excitability (Galeotti, 2001). These active components are found in high concentrations in spearmint leaves which can be consumed fresh or dried or distilled into spearmint oil. Spearmint oil is extracted through steam
distillation of fresh spearmint flowers and leaves (Hanrahan, 2001).

Current Use and Scientific Evidence

    Today, spearmint is most commonly used as a breath freshener in gum, mouthwash, toothpaste, and after dinner mints. However, there has been increasing scientific evidence to support the traditional use of spearmint as a soothing remedy for gastrointestinal upset, as well as mixed evidence as a nasal decongestant (Kunnumakkara, 2009). 
    One of the most prevalent traditional uses for spearmint is to treat gastrointestinal upset, nausea, vomiting, and flatulence. In 2006, Vejdani et al investigated the effect of Mentha spicata in combination with Melissa officinalis and Coriandrum sativum (a combination known as Carmint) as a treatment for abdominal pain and bloating in patients with irritable bowel syndrome (IBS). After the 60 day trial, patients taking Carmint three times a day experienced a significant decrease in abdominal pain and bloating compared to the placebo group, both in respect to number of days with discomfort and severity of discomfort experienced (Vejdani, 2006).
    The study by Vejdani et al (2006) shows a promising role for Carmint in the management of IBS symptoms.  Their protocol was well thought out, and their choice of using essential oils rather than tea made it possible for this study to be double blind placebo controlled, which strengthens their findings significantly.  All results were supported with statistical significance (Vejdani, 2006). Though their study did not investigate differences in efficacy for specific subtypes of IBS, it is a strongly supported pilot project that should be followed up with a more subtype specific, larger trial.
    A second popular traditional use of spearmint is the use of its active compound, menthol, in the treatment of respiratory distress caused by nasal congestion. In 2008, Kenia, Houghton and Beardsmore investigated the effect of inhaled methol on nasal air flow and volume (measured by a spirometer) and perception of nasal patency, as well as the number of coughs in response to inhaled citric acid. No significant relationship was found between objective nasal air flow or cough frequency and methol inhalation. However, there was a significant increase in subjective perception of nasal patency for the methol condition compared with placebo. The authors suggest that this discrepancy between objective and subjective measures may be due to the cooling effect of menthol increasing the perception of greater airflow.
    This study had several crucial limitations that effect its generalizability. Firstly, the participants were all healthy children, and respiratory conditions were an exclusion factor even though the use of spearmint to aid with respiratory distress is only traditionally used in patients with a cough, cold, flu or mild asthma (Kunnumakkara, 2009). Secondly, though it was a placebo controlled trial it was only single blind, with no indication for why they chose this protocol. This may be a source of bias explaining the discrepancy between objective and subjective results.

How to Treat a Stomach Ache With Natural Medicine (mint and ginger tea)

Adverse Effects and Drug Interactions

    Spearmint is generally safe with no adverse side effects when consumed in amounts naturally found in foods and beverages. It is safe and effective for use in adults, children and pregnant women, although no suggested dose is available (Natural Standard, 2010). However, there have been rare cases of allergic reactions to carvone resulting in dermatitis from contact with spearmint or respiration of the fragrance (Natural Standard, 2010). Though drug interactions have not been well studied, spearmint should be used cautiously by people with iron deficiency or who are taking iron supplements, as spearmint may further decrease iron absorption (Kunnumakkara, 2009). It should also be avoided by people who are currently taking CNS depressants as carvone may act as an antidepressant through modification of the acetylcholinesterase pathway (Natural Standard, 2010).

References

Adsersen, A. et al. (2006). Screening of plants used in Danish folk medicine to treat memory dysfunction for acetylcholinesterase inhibitory activity. Journal of Ethnophermacology. 104(3): 418-422

Galeotti, N. et al. (2001). Local anaesthetis activity of (+) - and (-)-menthol. Planta Medica. 67(2):174-176

Hanrahan, C. (2001). Spearmint. Encyclopedia of Alternative Medicine. Accessed 11/22/2010.
http://www.altmd.com/Articles/Spearmint--Encyclopedia-of-Alternative-Medicine

Kunnumakkara, A.B., Chung, J., Koca, C., Dey, S. (2009) Mint and its Constituents. pg. 373-401. IN: Aggarwal, B.B., Kunnumakkara, A.B. (2009). Molecular Targets and Therapeutic Uses of Spices. Singapore: World Scientific Publishing.

Natural Standard. (2010). Spearmint Mentha spicata/Mentha viridis. Your Natural Options. Accessed 11/18/2010.
http://resources.yournaturaloptions.com/supplements/spearmint

Rafii, F., Shahverdi A.R. (2007). Comparison of essential oils from three plants for enhancement of antimicrobial activity of nitrofurantoin against enterobacteria. Chemotherapy. 53 (1): 21-25

Vejdani, R., et al. (2006). The efficacy of an herbal medicine, Carmint, on the relief of abdominal pain and bloating in patients with irritable bowel syndrome: a pilot study. Digestive Diseases and Sciences. 51(8): 1501-1507

Wrigley’s Incorporated. (2010). Wrigley’s Spearmint. Accessed 11/23/2010.
http://www.wrigley.com/global/brands/spearmint.aspx