2014 年 40 巻 7 号 p. 383-388
Caffeine, a major component of coffee, exhibits pharmacological actions on the cardiovascular system. In the present study, we examined the acute effects of caffeine on blood pressure (BP) and heart rate (HR) and the influence of habitual coffee intake on cardiovascular responses to caffeine. In this double-blind, placebo-controlled study, 136 young normotensive Japanese subjects were randomized. The subjects were first divided into 84 non-habitual and 52 habitual coffee consumers and further subdivided into placebo and caffeine groups; in the placebo group they had a cup of decaffeinated coffee, whereas in the caffeine group they had a cup of caffeinated coffee. In non-habitual coffee consumers, the systolic and diastolic BP at 30, 60, and 90 min after coffee intake were significantly higher in the caffeine group than in the placebo group. However, the pressor effect of caffeine disappeared in habitual coffee consumers. The changes in HR after coffee intake were similar between the placebo and the caffeine groups in both consumers of coffee. These results suggest that a single cup of caffeinated coffee is capable of increasing BP, and that the acute pressor effect of caffeine is diminished by habitual coffee consumption.