A double-blinded, placebo-controlled, cross-over clinical trial was conducted with 24 healthy individuals as study participants. Study participants were given placebo capsules or capsules containing either 1 or 2 drops of peppermint essential oil. Participants were asked to perform a number of tasks designed to test cognitive function and assessed for mental fatigue.
The researchers found that peppermint essential oil had a positive effect on cognition during the execution of difficult mental tasks. In addition, peppermint essential oil significantly reduced cognitive fatigue.
Kennedy D, Okello E, Chazot P, et al. Volatile Terpenes and Brain Function: Investigation of the Cognitive and Mood Effects of Mentha × Piperita L. Essential Oil with In Vitro Properties Relevant to Central Nervous System Function. Nutrients. 2018;10(8). pii: E1029. doi: 10.3390/nu10081029.