Peppermint Oil May Lower Blood Pressure, Clinical Trial Suggests

High blood pressure substantially increases the likelihood of heart attacks, strokes and other cardiovascular diseases. That risk has prompted researchers to seek new, preferably simple, methods of lowering blood pressure readings.

Lifestyle adjustments may be beneficial, but many people struggle to maintain dietary changes or regular exercise programmes.

Medicines for blood pressure can also work well, yet taking them consistently may be difficult, and many people would prefer treatments that do not involve drugs where possible.

Peppermint oil and blood pressure

In a new clinical trial published in PLOS One, UK researchers examined the impact of a daily dose of peppermint oil in 40 volunteers aged 18 to 65 over 20 days.

The study was small and brief, but its findings were notable. Participants who received peppermint oil had an average fall in systolic blood pressure - the first, or upper, figure in a reading - of 8.48 millimetres of mercury (mmHg) compared with a placebo group.

This amounts to an 8-point decrease in blood pressure. For context, every 10-point reduction in systolic blood pressure is associated with a 20 percent lower risk of a heart event.

"Our findings were very positive and they have significant clinical implications, especially given arterial hypertension is the most common preventable risk factor for cardiometabolic disease and the greatest single risk factor for global mortality," says sports and health scientist Jonnie Sinclair, from the University of Lancashire.

For those unfamiliar with peppermint, extracts from the plant have long been used to relieve stomach pain and bloating, and are regarded as having antioxidant and anti-inflammatory properties.

Earlier studies had tentatively indicated that peppermint might assist with hypertension, leading the team behind this latest research to explore the possibility in greater detail.

Trial participants and daily dosage

Every participant had either pre-hypertension - blood pressure just under the formal high-blood-pressure threshold - or stage 1 hypertension, the lower range of high blood pressure.

One half of the group received 50 microlitres of pure peppermint oil mixed with 100 millilitres of water twice daily, while the remaining participants received a placebo.

As well as the meaningful reduction in systolic blood pressure, the peppermint group recorded an average 4.57 mmHg decrease in diastolic pressure, the second or lower reading. Following statistical adjustments, their resting heart rate was also, on average, 8.92 beats per minute (bpm) lower than that of the placebo group.

"The results of this trial suggest that peppermint supplementation could be a valuable tool in the management of pre-hypertension and stage 1 hypertension," write the researchers in their published paper.

How peppermint may affect hypertension

The reason peppermint appears to produce this effect remains uncertain. More research is required for a firm answer, although the researchers propose that menthol in peppermint may initiate a chemical response that relaxes blood vessels and enhances blood flow.

Future studies could investigate that proposed mechanism fully, but the early indications are promising.

"Peppermint oil is low in calories and price so it's proved to be a very simple and cost-effective solution to potentially treat millions of people around the world," says Sinclair.

As with all findings of this kind, people should not immediately attempt to reproduce the results themselves.

This was a controlled trial using one specific peppermint oil, a set dosage and a particular target group of patients. Do not try anything similar without first consulting a doctor.

The researchers' next stage will be longer trials involving larger groups and more continuous blood pressure monitoring. Those studies should provide further evidence on whether peppermint offers a practical, uncomplicated and natural approach to treating hypertension.

"High blood pressure is one of the biggest causes of heart disease and death worldwide, and it costs a huge amount of money to treat," says Sinclair.

"Although medicines are commonly used to treat it, it's not always clear how well they work in the long-term, and they can cause unwanted side effects."

The research was published in PLOS One.

This article was fact-checked by Fiona MacDonald and edited by Clare Watson. Although we take pride in our process, we are only human. If you notice an error, please let us know.