Coffee Drinking is Not Associated with Increased Risk of High Blood Pressure in Women

Coffee and Blood Pressure

Frequent consumption of coffee and other caffeinated beverages has been thought to increase the risk of high blood pressure. Now, researchers at Brigham and Women's Hospital (BWH), in the largest study to date, report that coffee drinking is not associated with an increased risk of hypertension; in fact, it appeared to be protective among the women who drank the most coffee. Interestingly, the researchers did find a link between frequent consumption of caffeine-containing colas and an elevated risk of being diagnosed with high blood pressure. These findings are published in the November 9, 2005 issue of the Journal of the American Medical Association.

According to lead author Wolfgang Winkelmayer, MD, ScD, a researcher in BWH's Division of Pharmacoepidemiology and Pharmacoeconomics, "Given that coffee and other caffeine-containing drinks are among the most widely consumed beverages in the world, any detrimental effects of caffeine on health could have enormous public health implications, especially for a silent, but extremely dangerous disease such as hypertension that impacts at least 50 million Americans alone. In this study of more than 155,000 women we have good news to share about their coffee habits. Based on our data, we can dispel the myth that habitual coffee drinking leads to hypertension in women. However, when examining individual beverages, the data indicate that soda consumption may be associated with an increased risk of hypertension."

The findings are based on participants enrolled in the Nurses' Health Study (NHS) I and II, two groups of women who ranged from age 26 to 71 at the start of the 12-year study. The nurses regularly completed a food frequency questionnaire that queried participants on their consumption of coffee, tea, and soda. The participants also reported when a physician had diagnosed them with hypertension.

Winkelmayer and colleagues did not find an association between consumption of caffeinated or decaffeinated coffee and an increased incidence of hypertension. But, instead, they found that cola beverages containing caffeine, both sugared and diet, did appear to have a link to an increased risk of being diagnosed with high blood pressure. Specifically, they report:

• The group of younger participants (ages 26 to 46 at the start of the study) who regularly drank four or more cans or glasses of caffeine-containing sugared cola per day had a 28 percent increased risk of hypertension compared to women who drank less than one can or glass per day.

• The group of older participants (ages 43 to 71 at the start of the study) who regularly drank four or more cans or glasses of caffeine-containing sugared cola per day had a 44 percent increased risk of hypertension compared to women who drank less than one can or glass per day.

• Among younger participants who drank four or more cans or glasses of diet cola, the risk was elevated by 19 percent compared to women who drank less than one can or glass per day.

• Among older participants who drank four or more cans or glasses of diet cola, the risk was elevated by 16 compared to women who drank less than one can or glass per day.

"People may be concerned about the effects of caffeine on health and some women may consider switching beverages based on information from studies such as this, so we are happy to report to all coffee aficionados that their morning or afternoon coffee ritual is not tied to their risk of developing high blood pressure," said Winkelmayer.

"Surprisingly, we found that another popular beverage, cola, may be a culprit, with initial indications that the women who drank the most caffeinated cola, both diet and sugared, were at the greatest risk for developing hypertension. At the present time there is no biological explanation for this association so until more research is done, no recommendations regarding soda-drinking and hypertension can currently be made."