Hypertension , or high blood pressure, is a major risk factor for coronary heart disease , stroke , and congestive heart failure . At present, it affects about 50 million people in the United States. Studies have shown that caffeine intake increases blood pressure in the short term, but that this effect weakens over time. Studies examining longer-term effects of caffeine on blood pressure are scarce.

In an article published in the November 9, 2005 Journal of the American Medical Association , researchers set out to determine whether women who regularly consumed caffeine had an increased risk of hypertension. They found no association between caffeine consumption and risk of hypertension.

About the Study

The researchers analyzed data from 155,594 women enrolled in the Nurses Health Studies (I and II), who were followed for 12 years, from 1990-91 to 2002-03. None of the women included in this analysis had been diagnosed with hypertension prior to 1990-91. The study participants responded to food frequency questionnaires every four years, specifying how often they consumed a variety of caffeinated foods and beverages including various sodas, coffee, tea, and chocolate. They also reported their intake of alcohol, sodium, and other dietary minerals. Finally, the study participants’ family histories were collected when they enrolled in the study, and information about their weight was updated every four years.

In these study participants, higher levels of caffeine consumption were not associated with increased risk of hypertension. This was true even after the researchers took other factors relevant to blood pressure—such as body mass index, alcohol consumption, and use of oral contraceptives—into consideration. Interestingly, while coffee consumption was also not significantly associated with hypertension risk, higher intake of caffeinated sodas (diet and regular) was associated with a significantly increased risk of hypertension.

How Does This Affect You?

This study demonstrated that in a large sample of predominantly white women, higher levels of caffeine consumption did not significantly increase the risk of hypertension. These findings may not apply to men, or to women of different racial and ethnic backgrounds.

Hypertension is a serious, but often silent condition, in that it produces no symptoms. Left untreated, it can lead to coronary heart disease, stroke, and congestive heart failure. Hypertension can often be prevented with some basic lifestyle changes such as losing weight if you’re overweight, staying active, not smoking, limiting alcohol consumption, and managing stress. Your morning cup of coffee, however, appears to be safe.