Keio University and Kirin confirm in clinical studies that bitter compounds in beer regulate autonomic nervous system activity and improve attention

A research group led by Professor Satoshi Umeda of the Cognitive Neuroscience Laboratory at the Department of Psychology at Keio University, and Senior Research Scientist Yasuhisa Ano of the Kirin Central Research Institute, R&D Headquarters at Kirin Holdings, has confirmed that a single intake of bitter acids from mature hops has the ability to improve attention by modulating autonomic nerve activity during cognitive function tests requiring attention in healthy adults in a randomised, placebo‐controlled, double‐blind, crossover, comparative clinical trial.

The study aimed to investigate the mechanisms of bitter acids from mature hops in humans. Previous non‐clinical studies have confirmed that bitter acids from mature hops improve cognitive and mental function via the vagus nerve, one of the autonomic nerves. A randomised, placebo‐controlled, double‐blind, crossover study was conducted to investigate the effect of bitter acids from mature hops on autonomic nervous system activity in humans. Thirty‐four participants (aged 30‐64 years) who passed the pre‐test were randomly assigned to two sequences (17 participants each) with different orders of intake of the test foods. Participants were asked to consume a placebo or a single capsule of mature hop‐derived bitter acids. Cognitive function tasks were performed before and after consumption of the test food. The researchers then measured heart rate variability with a heart rate monitor to monitor autonomic activity during the study.

The results showed a statistically significant increase in total power (TP; a measure of overall autonomic activity) during the performance of cognitive tasks in the mature hop bitter acids group compared to the placebo group. There was also a statistically significant improvement in the executive function score, calculated from performance on the Shifting Attention Test, which assesses attention function, in the mature hop bitter acids group compared to the placebo group.

These results indicate that consumption of bitter acids from mature hops modulates autonomic nervous system activity in healthy adults. Previous clinical trials have shown that continuous consumption of mature hop bitter acids improves cognitive functions such as memory and attention, but this trial has shown that even a single intake improves attention. Similarly, while previous studies have targeted middle‐aged and older people, the current study has shown that bitter acids from mature hops are effective for a wider range of people, from 30 to 60 years old.

"We have confirmed that a single intake of hop bitter acids increases autonomic nervous system activity and improves attention functions that require concentration," noted Ano. "The social implementation of this component in food and beverages is underway, and further clinical findings, such as the evaluation of brain activity, are expected to lead to the spread of healthcare solutions based on scientific evidence in the future."

■ Randomised, placebo‐controlled, double‐blind, crossover comparison: A method in which subjects are randomly divided into two groups, with each group receiving a separate intervention (placebo or treatment/food). The intervention is then reversed for each group, reassessed, and the treatment/food and placebo are compared

Journal Information
Publication: Journal of Functional Foods
Title: Effects of matured hop bitter acids on heart rate variability and cognitive performance: A randomized placebo‐controlled crossover trial
DOI: 10.1016/j.jff.2022.105383