Coffee is one of the most widely consumed beverages, and some studies have suggested it may lead to cardiovascular disease (CVD), the leading cause of death in the United States. Most of the effects attributed to the chronic use of coffee on the heart rate variability (HRV) indexes have been found to result from the higher prevalence of unhealthy habits in coffee users, such as smoking and alcohol use, not coffee drinking itself. Adjustment for these confounding factors weaken the association that drinking coffee will lead to heart disease.
A review of the evidence on the effect of habitual coffee consumption on CVD incidence and mortality found that 3-5 cups of coffee per day is associated with a 15 percent reduction in the risk of CVD. Compared to no coffee intake, usual consumption of 1-5 cups/day is associated with a lower risk of death. In people who have already suffered a CVD event, habitual consumption does not increase the risk of a recurrent CVD or death. However, hypertensive patients with uncontrolled blood pressure should avoid consuming large doses of caffeine. In persons with well-controlled blood pressure, coffee consumption is probably safe, but further investigations are needed to confirm this hypothesis.
One of the largest studies on the relationship between coffee and CVD concluded, “Our findings do not support the hypothesis that coffee consumption increases the long-term risk of coronary heart disease. Habitual moderate coffee drinking was associated with a lower risk of CHD in women.
In another large-scale study, Neal Freedman, Ph.D., Division of Cancer Epidemiology and Genetics, NCI, and his colleagues examined the association between coffee drinking and risk of death in 400,000 U.S. men and women ages 50 to 71 who took part in the NIH-AARP Diet and Health Study. Information about coffee intake was collected once by questionnaire at study entry in 1995-1996. They followed the participants until the date they died or Dec. 31, 2008, whichever came first. In this study, they found a 10 percent reduction lower risk of death by those who drank coffee over those who did not.