The participants were asked how many cups of coffee per day they drank, type of coffee (regular, decaf or other), and whether they added milk or sweeteners. The participants had follow-up visits at six and 11 years.
Hypertension was defined as a mean systolic blood pressure of 140 mm Hg or higher over both follow-up measurements, a mean diastolic of 90 mm Hg or higher over both follow-up measurements, or the use of antihypertensive medication at any follow-up.
The authors found that people who never drank coffee at all had a lower risk for hypertension than light coffee consumers — those who drank between one and three cups daily. The adjusted odds ratio for coffee abstainers versus light drinkers was 0.54 (95% confidence interval, 0.31-0.92).
On the other end of the scale, women who drank more than six cups of coffee per day had a lower hypertension risk than women who drank between zero and three cups (adjusted odds ratio 0.67; 95% CI: 0.46-0.98).
Men who did not drink coffee also had a lower risk relative to those drank one to three cups daily (adjusted odds ratio 0.60 (95% CI, 0.24-1.49), but adjusted odds ratios for the other two consumption categories, four-to-six cups, and more than six cups daily, were close to 1.00 (1.08, 95% CI 0.79-1.47 and 1.03, 95% CI, 0.72-1.46, respectively).
The authors also found an association between age, hypertension, and coffee consumption. Men and women age 39 and over at baseline had 0.35 mm Hg lower systolic pressures for every cup of coffee they drank daily (95% CI: -0.59 to – 0.11mm Hg), and 0.11 mg Hg lower diastolic pressure (95% CI, -0.26 to -0.03 mm Hg) compared with younger participants, but the latter was not statistically significant.