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The Effects of Caffeine on Human Blood Pressure

Caffeine is a stimulant found in coffee, some sodas and teas, energy drinks and chocolate. While popular for its ability to give consumers a quick energy boost through the day, researchers and doctors have studied the effect of caffeine consumption on human health, especially blood pressure.

  1. What is Blood Pressure?

    • Blood pressure is the measure of force the blood uses as it presses against the artery walls while circulating through the body. The top number of the reading or measurement is called systolic pressure. The lower number is called diastolic pressure. Hypertension or high blood pressure occurs when blood pushes against the artery walls harder than normal. This excess force puts strain on the blood vessels and increases the workload on the heart.

    Effect on Normal Blood Pressure

    • According to Dr. Sheldon G. Sheps, a Mayo Clinic hypertension specialist, caffeine can cause a sharp increase in normal blood pressure, though this effect is temporary. He said the amount of caffeine in two to three cups of coffee can raise systolic pressure three to 14 mm of mercury (mm Hg) and diastolic pressure four to 13 mm Hg. It is important to note that these numbers reflect changes in pressure for individuals who do not consume caffeine regularly basis.

    Effect of Varying Blood Pressure Levels

    • In a study performed in 2000 among caffeine-consuming men with varying levels of blood pressure, the American Heart Association reports there was minimal blood pressure increase among males falling in normal pressure ranges. However, in hypertensive males, the blood pressure increase was higher, with males on prescribed medication for hypertension reporting the highest increase in pressure numbers with caffeine consumption. While pressure increase was higher for hypertensive males, the American Heart Association has still determined that for non-hypertensive individuals the increase is not substantial enough to consider caffeine harmful to normal blood pressure.

    Caffeine and Adolescents

    • Dr. Margaret R. Savoca, nutritionist and post-doctoral fellow at the Medical College of Georgia, asserts that the effect of caffeine on adolescents has not been studied as extensively as adults. In the study featured in Pediatric & Adolescent Medicine, researchers found caffeine-consuming adolescents outnumber those who don't drink caffeine by two to one. With rising rates of adolescent hypertension, Savoca suggests that caffeine could be an indicator of practices that affect blood pressure in youth.

    Research Controversy

    • The controversy in reports and findings on caffeine's affect on blood pressure can be linked to the way in which most studies have been performed. According to a report in Hypertension, a Journal of the American Heart Association, historical studies of the effects of caffeine on blood pressure tried to use candidates with little or no previous exposure to caffeine. The AHA reports that even with numerous studies, there still is no certainty in the medical community that blood pressure increases occur under ideal laboratory conditions mirror the increases that would potentially be found in observation of regular daily activities of research participants. With caffeine tolerance reportedly achieved in as little as one to two days of consumption, analysis is still inconclusive regarding caffeine's effect on the blood pressure of people with caffeine tolerance.

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