Peppermint tea boosts memory and attention—but why?

A new study published in Human Psychopharmacology: Clinical and Experimental adds to growing evidence that peppermint can improve memory and attention in healthy adults. The findings show that drinking a modest dose of peppermint tea improved several types of cognitive performance compared to a placebo. These benefits were accompanied by increased blood flow in the prefrontal cortex—the part of the brain responsible for functions such as attention and working memory. But unexpectedly, these vascular changes did not explain the improvements in cognition, suggesting that other mechanisms may be responsible.

Previous research has suggested that peppermint can improve attention, working memory, and even mood. Some scientists have proposed that these benefits arise because peppermint increases cerebral blood flow, especially in the prefrontal cortex. This would allow more oxygen and nutrients to reach the brain, potentially enhancing mental performance. Others have pointed to peppermint’s active ingredients, such as menthol, which may influence neurotransmitter systems involved in cognition. The current study aimed to test whether improved blood flow really acts as a bridge between peppermint and better thinking.

“The project was conceptualized and executed by my master’s student, Luka Netzler, who has now gone onto to study for a PhD,” explained corresponding author Brian Lovell, an associate professor at Northumbria University.

“The cognitive enhancing effects of peppermint are well established, but little attention has been paid to the possible mechanisms, particularly neurovascular mechanisms, that might underlie these effects. Here, we wanted to explore this more, asking whether acute (short term) positive changes in cognition, particularly memory and attention, following consuming small amounts of peppermint team might be mediated by increased oxygenated blood flow to the prefrontal cortex, assessed with fNIRS.”

The researchers at a UK-based institution recruited 25 healthy adult volunteers, aged between 20 and 56 years, and randomly assigned them to one of two groups. One group consumed a cup of peppermint tea, while the other received a placebo—a cup of warm water that participants were told contained peppermint extract. This single-blind design ensured that participants were unaware of which condition they were in, helping to control for expectation effects.

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Participants completed a battery of computerized tasks both before and after drinking their assigned beverage. These tasks measured a range of mental functions, including memory, attention, and visuospatial processing. For example, the picture recall task tested episodic memory by asking participants to recognize previously viewed images. Another task, called serial threes, required participants to subtract three repeatedly from a large number, which tests attention and working memory. The study also included tasks for short-term word recall and visuospatial memory.

At the same time, researchers used near-infrared spectroscopy, or NIRS, to monitor changes in brain activity by measuring blood oxygenation levels. This non-invasive method tracks the relative concentrations of oxygenated and total hemoglobin in the brain and is especially well suited to measuring blood flow in the prefrontal cortex. Measurements were taken both at rest and during task performance, both before and after the intervention.

The results showed that participants who drank peppermint tea performed better on all four cognitive tasks after consumption. They showed greater improvements in episodic memory, working memory, short-term word recall, and visuospatial memory compared to the placebo group. These differences were statistically significant and consistent across the different tasks.

Interestingly, the placebo group actually showed a slight decline in performance on some tasks during the second round of testing, which might reflect the effects of fatigue or reduced motivation—something that peppermint appears to have buffered against.

In addition to cognitive improvements, those in the peppermint group also showed increased blood oxygenation in the prefrontal cortex. Two key markers of hemodynamic activity—oxygenated hemoglobin and total hemoglobin—were significantly higher after drinking peppermint tea. These effects were not observed in the placebo group, supporting the idea that peppermint promotes greater cerebral blood flow.

“Peppermint, consumed as a tea, engenders short term improvements in cognition, particularly memory and attention,” Lovell told PsyPost. “Our protocol did not permit us to investigate the sustainability of these beneficial cognitive effects.”

Despite this, the researchers found no connection between changes in blood flow and improvements in cognitive performance. Statistical analyses showed that the rise in blood oxygenation did not predict how much a participant’s memory or attention improved. Even after adjusting for blood flow changes, the cognitive benefits of peppermint remained significant. This suggests that increased blood flow is not the reason why peppermint improves thinking, at least in the short term.

This result was somewhat surprising to the research team, who had expected blood flow to play a mediating role. It’s possible that the small sample size limited their ability to detect a relationship, Lovell said. Larger studies are generally needed to test mediation effects reliably, especially when the links between variables are subtle. The researchers also noted that the way NIRS data was handled may have influenced the outcome. Future studies might benefit from more detailed analyses of the timing and location of blood flow changes.

One alternative explanation is that peppermint affects brain chemistry in ways that are independent of blood flow. Menthol, a major compound in peppermint, interacts with receptors involved in the cholinergic system, which plays a key role in learning and memory. Menthol may help preserve acetylcholine levels in the brain by blocking enzymes that break it down, enhancing the transmission of signals between neurons. It also activates certain receptor channels that influence alertness and sensory processing. These chemical pathways may offer a better explanation for peppermint’s cognitive effects than changes in blood supply alone.

The study’s findings are in line with previous work showing that peppermint can sharpen mental performance. Unlike many earlier studies that used peppermint aroma, this one used a relatively small dose of peppermint tea—just 200 milliliters. The low dose and simple preparation suggest that peppermint may be a practical and natural tool for improving cognitive performance in everyday settings. The fact that the placebo group’s performance declined on some tasks while the peppermint group improved raises the possibility that peppermint may help combat short-term mental fatigue.

While the results are promising, the authors caution that the study has limitations. Most notably, the sample size was small, and the design only assessed short-term effects. It is unknown how long the cognitive benefits of peppermint might last. The study also did not control for participants’ diet, caffeine intake, or physical activity, all of which can influence cognition and blood flow.

The study also raises questions for future research. For instance, if blood flow is not the mediator, what is? Further studies could explore other physiological or chemical processes, such as changes in neurotransmitters, that might account for the observed effects. It may also be useful to test different doses of peppermint or to examine whether specific compounds in the plant are more responsible for its benefits. Menthol is likely not the only active ingredient—peppermint contains a range of other chemicals, including menthone and limonene, which might also influence brain function.

In the long run, Lovell said he hopes to build on these results by conducting larger studies with more post-intervention assessments and more precise imaging techniques. By examining how different compounds in peppermint affect the brain and how long the benefits last, they aim to better understand the potential of this everyday herb to support cognitive health.

The study, “A Randomized Placebo-Controlled Clinical Trial Exploring the Short-Term Cognitive and Cerebrovascular Effects of Consuming Peppermint Tea: A Mediation Study,” was authored by Luka Netzler and Brian Lovell.