Peppermint oil is extracted from the herbaceous peppermint plant, which is a hybrid of spearmint and watermint. Multiple human studies have demonstrated that peppermint oil is effective in alleviating symptoms of irritable bowel syndrome, which is characterized by abdominal pain and irregular bowel habits. A review in the November 2008 issue of the "British Medical Journal" reports that the incidence of irritable bowel syndrome ranges between 5 and 20 percent in the general population.
Mechanism
Although the large intestine harbors a large amount of bacteria, the small intestine does not. An overgrowth of bacteria in the small intestine has sometimes been linked to irritable bowel syndrome and other diseases characterized by pronounced indigestion and abdominal pain. A review in the October 2002 issue of "Alternative Medicine Review" reports that peppermint oil has been shown to inhibit the growth of more than 22 bacterial strains including ones that are pathogenic. Peppermint oil additionally acts as a smooth muscle relaxant and relaxes the colon.
Human Studies
The authors of the assessment of four studies in the "British Medical Journal" conclude that peppermint oil is effective in alleviating symptoms of irritable bowel syndrome. A study in the January 2001 issue of "The Journal of Pediatrics" reports that enteric-coated peppermint oil capsules administered for 2 weeks reduced the severity of pain in 75 percent of children with irritable bowel syndrome.
Dosage
The article in "Alternative Medicine Review" reports that in most of the human studies evaluating the effectiveness of peppermint oil for treating irritable syndrome the dose administered was 0.2 mL enteric-coated peppermint oil three times daily. An article in the April 2007 issue of "American Family Physician" reports that peppermint oil is commonly administered to adults at doses between 0.2 and 0.4 ml of oil three times daily in enteric-coated capsules. In children older than 8 years the dose is 0.1 to 0.2 ml also three times daily.
Safety
The article in "American Family Physician" notes that peppermint oil is generally well tolerated at the recommended doses but higher doses may cause adverse effects including blurred vision, nausea, vomiting, heartburn and allergic reactions. An assessment of the toxicity of peppermint oil in the January 2001 issue of the "International Journal of Toxicology" reports that in rodents acute oral administration of peppermint oil was minimally toxic. This study also reports that repeated dermal exposure to peppermint oil produced moderate to severe skin reactions in rabbits, but it did not act as a skin allergen. A study in the September 1992 issue of "Toxicology Letters" reports that in longer-term studies, high doses of peppermint oil were associated with lesions on the brain stem in rats. The lesions were not fully characterized and a no-adverse-effect level of 40 mg per kg per day was determined.
References
- PubMed Central: Effect of Fibre, Antispasmodics, and Peppermint Oil in the Treatment of Irritable Bowel Syndrome: Systematic Review and Meta-Analysis
- "Alternative Medicine Review"; The Treatment of Small Intestinal Bacterial Overgrowth with Enteric-Coated Peppermint Oil: A Case Report; A.C. Logan and T.M. Beaulne; October 2002
- PubMed: Enteric-Coated, pH-Dependent Peppermint Oil Capsules for the Treatment of Irritable Bowel Syndrome in Children
- PubMed: Final Report on the Safety Assessment of Mentha Piperita (Peppermint) Oil, Mentha Piperita (Peppermint) Leaf Extract, Mentha Piperita (Peppermint) Leaf, and Mentha Piperita (Peppermint) Leaf Water
- PubMed: Subchronic Toxicity Study of Peppermint Oil in Rats
- "American Family Physician"; Peppermint Oil; B. Kligler and S. Chaudhary; April 2007
