I take my blood pressure a few times a day. When I first get up in the morning, it’s a little below normal, but it becomes high after I drink a few cups of coffee. My husband does the same thing, but his blood pressure hardly changes. What’s going on?
A cup of brewed coffee contains about 100 mg of caffeine, a stimulant that helps us feel more alert in the morning, but it also increases heartbeat and temporarily raises blood pressure. Once the caffeine passes out of your system, which usually takes about five hours or so, your blood pressure should go down. Some people, however, are more sensitive to the effects of caffeine, whether it be in coffee, energy drinks or certain foods such as chocolate. Caffeine is metabolized in the liver by the CYP1A2 enzyme. We are genetically programmed to metabolize caffeine in one of two ways…
- Rapid metabolizers, about 45% of the population, can consume up to 400 mg of caffeine (about four cups of brewed coffee) daily with little effect on blood pressure—even in the short term.
- Slow metabolizers, about 55% of the population, have very low CYP1A2 activity. Their blood pressure will stay elevated for up to four to five hours. These people also may have tachycardia (fast heart rate) and increased adrenaline levels, which can cause the jitters and wakefulness.