Effects of kaempferol on weather-related pain: an open-label pilot study of subjective headache and other discomforts in pre-intervention and intervention periods in Japan.

Adverse or fluctuating weather conditions can negatively affect health, causing symptoms known as weather-related pain. Although pharmacological treatments, including painkillers, are commonly used, they frequently provide only symptomatic relief and may cause side effects. Therefore, interest in non-pharmacological and dietary interventions is increasing. While inner ear sensitivity to barometric pressure fluctuations—activating the sympathetic nervous system—has traditionally been considered the main mechanism, we propose that reduced oxygen utilization due to peripheral hypoxia under low barometric pressure is also a key factor. Kaempferol, a dietary flavonoid, has been shown in prior studies to enhance oxygen utilization and promote parasympathetic nervous system dominance. We hypothesized that daily kaempferol intake would alleviate weather-related discomfort by improving oxygen use and autonomic balance. In this pilot study, 458 individuals with moderate weather-related symptoms took 10 mg of kaempferol daily for 4 weeks. Participants completed questionnaires before and after the intervention. Data from 387 individuals with over 80% adherence were analyzed. Results showed significant reductions in symptom frequency (e.g., headache: Cohen’s d = 0.61, p < 0.001), duration (rank-biserial correlation = 0.64, p < 0.001), and severity (Cohen’s d = 0.57, p < 0.001). By the end of the intervention, over 80% of participants reported symptom improvement. These findings suggest that kaempferol is a promising non-pharmacological strategy for managing weather-related physical and mental symptoms by targeting oxygen utilization and autonomic regulation. This trial is registered with the UMIN Clinical Trials Registry (UMIN000045066).