Women and hypertension, coffee is fine, cola is not
14 Nov 2005Habitual coffee drinking is not associated with an increased risk of
hypertension in women, although an association was found with the consumption of
sugared or diet colas, according to a study in the November 9 issue of JAMA.
Approximately 50 million people in the United States have hypertension, and the
prevalence is increasing, according to background information in the article.
Hypertension is a major risk factor for coronary heart disease, stroke, and
congestive heart failure. Therefore, even small reductions in the prevalence of
hypertension could have a potentially large public health and financial impact.
Several previous studies have indicated a possible association between caffeine
intake and the risk of hypertension. Short-term studies have demonstrated that
caffeine intake acutely increases blood pressure, but over time, weakening of
this effect does occur. A long-term effect of caffeine intake on the risk of
developing hypertension would be of substantial public health importance given
the widespread consumption of beverages containing caffeine, but currently,
studies of this association are scarce.
Wolfgang C. Winkelmayer, M.D., Sc.D., of Brigham and Women's Hospital and the
Harvard School of Public Health, Boston, and colleagues conducted a study to
determine whether caffeine intake or consumption of certain caffeine-containing
beverages is associated with an increased risk of incident hypertension in
women. The researchers analyzed data from the Nurses' Health Studies (NHSs) I
and II of 155,594 U.S. women free from physician-diagnosed hypertension, who
were followed-up over 12 years (1990-1991 to 2002-2003). Caffeine intake and
possible confounders were ascertained from regularly administered
questionnaires.
Over the 12 years, 19,541 incident cases of physician-diagnosed hypertension
were reported in NHS I and 13,536 in NHS II. In both cohorts, no linear
association between caffeine consumption and risk of incident hypertension was
observed after multivariate adjustment. When studying individual classes of
caffeinated beverages, habitual coffee consumption was not associated with
increased risk of hypertension. By contrast, consumption of cola beverages was
associated with an increased risk of hypertension, independent of whether it was
sugared or diet cola.
"In this study with more than 1.4 million person-years of follow-up [the
number of women in the study times the number of years of follow-up per woman],
the relevant exposures and outcomes have been found valid and accurate, and
coffee intake was updated to reflect changes in individual behavior. We found
strong evidence to refute speculation that coffee consumption is associated with
an increased risk of hypertension in women," the authors write.
Concerning the link found between colas and hypertension, the researchers write:
"? we speculate that it is not caffeine but perhaps some other compound
contained in soda-type soft drinks that may be responsible for the increased
risk in hypertension. If these associations are causal, they may have
considerable impact on public health."
(JAMA.2005; 294:2330-2335.)
For funding/support information, please see the JAMA article.
Amy Dayton Smith
JAMA and Archives Journals
http://www.jamamedia.org