Peppermint

Peppermint (Mentha piperita) is a plant which is a hybrid from watermint and spearmint, used initially for culinary and food manufacturing purposes but has also been used for its supposed medicinal benefits. Peppermint has an oil component which appears to be its medicinal component, and this oil has a very large content of menthol which is seen as its bioactive ingredient. This menthol is nontoxic at the recommended dose, but is the same menthol also found in some cigarette products.

The main medicinal role of peppermint is due to its muscle relaxing properties in the stomach and intestinal tract, and internal usage of peppermint appears to be able to speed up the early phase of digestion in the stomach while reducing colonic motility. It is known as a carminative agent (thought to relief flatulence), and it has a fair bit of evidence to supports its usage in reducing abdominal pain in persons with irritable bowel syndrome (IBS). It doesn't seem to influence other symptoms of IBS too much, but the reduction of abdominal pain is quite notable.

Other possible benefits of peppermint oil include fast headache relief (which involves applying a topical solution of 10% peppermint oil to the scalp at the onset of a tension headache) and possibly a reduction in nausea when used as aromatherapy. It is safe with the recommended dosages, but overconsumption of peppermint oil supplements does have a toxic level which is feasible to reach intentionally.

Oral supplementation of peppermint oil for the purpose of gastrointestinal health and motility involves consuming anywhere between 450-750mg of the oil daily in 2-3 divided doses, and this is around 0.1-0.2mL of the oil itself per dosage. The exact optimal dosage of peppermint is not known, and the numbers reflect a menthol content somewhere between 33-50%.

Usage of peppermint for the treatment of headaches involves having a solution of 10% peppermint oil and applying a relatively thin layer to the front of your head upon the start of a headache, with another application after 15 minutes and 30 minutes (for three applications in total).

Usage of peppermint for aromatherapy does not follow any particular dosing, and similar to other forms of aromatherapy it should be used as either an oil or in a distiller until a pleasant aroma permeates the vicinity.

Any form of peppermint oil should be effective although for persons who experience heartburn (acid reflux) and wish to supplement with peppermint oil for their intestines, then an enteric coated capsule would be useful (since the muscle relaxing effects may affect the esophagous if the capsule breaks prematurely).

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects peppermint has on your body, and how strong these effects are.

Grade	Level of Evidence [show legend]
	Robust research conducted with repeated double-blind clinical trials
	Multiple studies where at least two are double-blind and placebo controlled
	Single double-blind study or multiple cohort studies
	Uncontrolled or observational studies only

Level of Evidence ? The amount of high quality evidence. The more evidence, the more we can trust the results.	Outcome	Magnitude of effect ? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.	Consistency of research results ? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.	Notes
	Irritable Bowel Syndrome	Notable	Very High See all 8 studies	In persons with IBS, supplementation of peppermint oil appears to reliably and effectively reduce abdominal pain for as long as it is taken. Benefits are no longer seen two weeks after supplement cessation and abdominal pain is the only symptom notably reduced.
	Nausea	Minor	High See all 5 studies	There appears to be interactions with peppermint as aromatherapy and reducing nausea, but the best evidence at this point in time is mixed and with some faults. More research is needed to see the potential role of peppermint aromatherapy in nausea reduction
	Treatment of Headaches	Notable	Very High See 2 studies	Preliminary evidence suggests that topical application of peppermint oil is effective in reducing tension headache severity when applied at the start of the headache (can work within 15 minutes), and is comparable to 1,000mg acetominophen in potency
	Colonic Tension	Minor	- See study	Supplementation of peppermint oil four hours prior to a colonoscopy eases tension in the colon and aids reduces complaints associated with treatment.
	Flatulence	Minor	- See study	Flatulence as a side-effect of IBS is reduced with ingestion of peppermint oil
	Irritability	Minor	- See study	Irritability as a side-effect of tension headaches is reduced secondary to the treatment of tension headaches
	Nipple Cracks	Minor	Very High See 2 studies	Topical application of peppermint oil or water appears to be more effective than placebo in alleviating nipple cracks in breastfeeding women
	Pain	Minor	- See study	Pain has been noted to be reduced in instances where pain is associated with tightened intestinal tissue (ie. during a colonoscopy) or during tension headaches. No inherent analgesic effect is known
	Rate of Gastric Emptying	Minor	- See study	A slight increase in the rate of gastric emptying is noted with peppermint oil, which is thought to be of benefit to persons with GERD
	Subjective Well-Being	Minor	Very High See all 3 studies	Although mood state during cognitive testing is unaffected, quality of life is increased when headaches or abdominal pain is being treated with peppermint oil.
	Treatment of Diffuse Esophageal Spasms	Notable	- See study	The pilot study on this topic did not have a placebo control, but noted complete resolution of spasms in all persons following a single supplemental dose of peppermint oil; a large amount of promise
	Attention	Minor	Moderate See 2 studies	Although there is no influence acutely in cognitive testing, there appears to be improvements in sustained attention processing with prolonged testing (10-40 minutes) with the aroma of peppermint. Suggesting an anti-fatigue effect.
	Calmness	-	- See study	Subjective ratings of calmness during cognitive testing are not significantly influenced with the aroma of peppermint
	Memory	-	- See study	The aroma of peppermint has been unable to influence memory processing (quantity or quality of memory formation) relative to control
	Processing Accuracy	-	- See study	Processing accuracy does not appear to be significantly influenced with acute inhalation of peppermint extract during cognitive testing
	Processing Speed	-	- See study	Processing speed is not significantly influenced with the aroma of peppermint during cognitive testing
	Sedation	-	- See study	Peppermint aromatherapy does not appear to significantly influence the state of wakefulness
	Working Memory	-	- See study	Working memory does not appear to be influenced with the aroma of peppermint

Studies Excluded from Consideration

• Confounded with ursodeoxycholic acid^[1]

• Used alongside other herbs in aromatherapy^[2]

• Used intragastric spraying of peppermint oil or isolated menthol rather than oral administration^[3][4][5][6]

• Confounded with caraway oil^{[7][8][9][10][11]}

• Peppermint oil soothes symptoms of irritable bowel syndrome

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