Effects of matured hop bitter acids on heart rate variability and cognitive performance: A randomized placebo-controlled crossover trial

Matured hop bitter acids (MHBA), produced by aging the hops used to make beer, activate the vagus nerve via bitter taste receptors and improve depression and cognitive function in mice. However, researchers have not investigated their effects on human autonomic nerves. This crossover study aimed to investigate the association between MHBA and the vagus nerve. We randomly assigned 34 participants (age: 30–64 years) into two sequences (n = 17 each). They performed cognitive tasks before and after a single supplementation with placebo or MHBA. We monitored the autonomic nerve activity using heart rate variability. Compared with placebo, MHBA supplementation significantly increased the high frequency (HF) and total power during cognitive tasks (322.2 ms² [95 % confidence interval (CI), 28.0, 616.4]; p = 0.033 and 630.6 ms² [95 % CI, 87.0, 1174.2]; p = 0.025, respectively). In summary, MHBA supplementation modulates the HF of parasympathetic nerve activity in healthy adults.