Effect of coffee intake on blood pressure in male habitual alcohol drinkers

Many cross-sectional epidemiological studies have revealed that alcohol consumption is closely related to an increase in blood pressure, which is known to be associated with an elevated serum T-glutamyltransferase (GGT) level, rather than to the volume of alcohol consumed. Since recent studies showed that coffee intake is inversely related to serum GGT, we investigated the effect of coffee on blood pressure in habitual alcohol drinkers. A total of 42 male hypertensive or prehypertensive volunteers who consumed alcohol and coffee daily completed this randomized controlled crossover trial. After a 2-week baseline period, these participants were randomly assigned to either a coffee-drinking group or a non-coffee-drinking group for the first 4 weeks. The situation was then reversed for the next 4 weeks. All participants continued their usual alcohol consumption. Blood pressure was measured once a week and compared between the two groups. After 1 week of coffee intake of more than 3 cups per day, the systolic and diastolic blood pressure began to fall slowly, and cessation of coffee intake raised the blood pressure. Systolic blood pressure was lowered by 7-10 mmHg, and diastolic pressure by 3-7 mmHg in 4 weeks. Alcohol consumption of more than 60 ml per day was maintained and there were no lifestyle changes in the participants of either group throughout the study period. Analyses of urine electrolytes and urea nitrogen indicated that there were no significant dietary changes. In conclusion, coffee intake of more than 3 cups per day in hypertensive and prehypertensive men who regularly consume alcohol lowers blood pressure.