Effects of peppermint oil (Mentha piperita L.) on cardiometabolic and other health related outcomes: a placebo randomized controlled trial.

Abstract

Background: There is growing speculation that peppermint may target the mechanisms central to cardiometabolic pathophysiology, though there has yet to be any randomized interventions, examining the efficacy of peppermint supplementation on cardiometabolic outcomes. This trial aimed to examine the effect of peppermint supplementation on cardiometabolic and other health indices following a 20-day supplementation period. Methods: A randomized, placebo-controlled parallel study design was adopted (NCT05071833). Thirty-six healthy adults were assigned into either peppermint or placebo trial arms, of which they drank 50 μL of either peppermint or peppermint flavoured placebo, diluted in 100 mL of water twice per day for 20 days. Participants were blinded to their trial arm assignment, lead investigators and those analyzing the data were blinded until the data were analyzed and those involved in collecting the data were aware of trial arm allocation. The primary outcome was systolic blood pressure, and secondary measurements included anthropometric, energy expenditure, substrate oxidation, blood lipid, diastolic blood pressure/resting heart rate, psychological wellbeing, and sleep efficacy. All measurements were obtained at baseline and after the 20-day intervention period. Results: There were significantly greater reductions in the primary outcome (-4.53mmHg (95% CI = -8.39 - -0.66) d=-0.81) and in triglycerides (-0.30mmol/L (95% CI = -0.52 - -0.08) d=-0.92) in the peppermint group compared to placebo. Furthermore, both state (-5.43 (95% CI = -11.33 - -0.56) d=-0.73) and trait (-5.18 (95% CI = -10.76 - -0.40) d=-0.74) anxiety indices improved statistically in the peppermint arm compared to placebo. No other statistically significant findings were observed. Conclusion: As both hypertension and high triglyceride levels are important parameters for the aetiology and severity of cardiometabolic disease, this trial indicates that twice daily peppermint supplementation (50μL) may represent an effective means to prophylactically enhance cardiometabolic health. Furthermore, given the negative effects of anxiety on health-related quality of life and psychological wellbeing, peppermint may also be effective in improving both state and trait anxiety.