Association between habitual coffee consumption and blood pressure levels.

The relationship between habitual coffee consumption and blood pressure was investigated in 9601 subjects (7506 men and 2095 women) who were office managers and employees, aged 18-65 years. Those who drank coffee had lower blood pressure levels than those who did not and the mean blood pressure levels decreased with increasing coffee consumption. In the men, blood pressure (systolic/diastolic) was highest in the non-coffee drinkers (130.0/83.0 mmHg) and lowest in those drinking greater than 5 cups/day (126.0/81.3 mmHg). Mean differences (+/- s.e.m.) corrected by analysis of covariance for age and body mass index (kg/m2) were: systolic -4.0 +/- 0.7 mmHg, P less than 0.0001; diastolic -1.7 +/- 0.5 mmHg, P less than 0.001. In the women, blood pressure ranged from 121.1/77.4 mmHg in the non-coffee drinkers to 117.7/76.2 mmHg in those drinking greater than 5 cups/day (mean +/- s.e.m. systolic difference -3.4 +/- 1.4 mmHg, P less than 0.05; diastolic -1.2 +/- 0.9 mmHg, P greater than 0.05). These observations were confirmed after correction for physical activity, and cigarette and alcohol consumption (for age and body mass index). In the men, blood pressure ranged from 130.8/83.1 mmHg in non-coffee drinkers to 127.5/81.9 mmHg in those drinking greater than 5 cups/day, with the effect of classification by coffee consumption being very important (analysis of covariance: systolic F = 12.17, 3 degrees of freedom at numerator, P less than 0.0001; diastolic F = 3.56, 3 degrees of freedom at numerator, P = 0.0135).(ABSTRACT TRUNCATED AT 250 WORDS)