There's been some debate about whether or not coffee is good or bad for the heart. Now, a very large study of human health data has determined that drinking coffee doesn't raise a person's risk of cardiac arrhythmia, which can refer to any change in the electrical signals that control the movement of the heart. These signals may cause the heart to beat too slowly, too rapidly, or erratically, any of which may disrupt the flow of blood to the body and have serious health consequences.
This research assessed just over 386,000 male and female coffee drinkers with an average age of 56. The massive study found that arrhythmia risk was lowered slightly as the number of daily cups drank increased; each additional daily cup was linked to a three percent reduction in the risk of any arrhythmia. These included common heart problems like atrial fibrillation or premature ventricular contractions. The findings have been reported in JAMA Internal Medicine.
"Coffee is the primary source of caffeine for most people, and it has a reputation for causing or exacerbating arrhythmias," noted corresponding study author Gregory Marcus, M.D., a professor of medicine in the Division of Cardiology at the University of California, San Francisco.
The research “found no evidence that caffeine consumption leads to a greater risk of arrhythmias. Our population-based study provides reassurance that common prohibitions against caffeine to reduce arrhythmia risk are likely unwarranted," added Marcus.
Coffee may actually be beneficial. Some research has indicated that coffee can have anti-inflammatory effects and may help reduce the risks of some diseases including cancer, but the findings are inconsistent.
This study is one of many that have leveraged the statistical power of the UK Biobank and the trove of human genetic and health data it contains. These researchers followed up on the study participants for four years and a. About four percent of these individuals developed a heart arrhythmia during that time. Even people with a genetic predisposition to metabolize coffee faster and who drank more coffee did not have an increased risk of arrhythmias. Higher coffee intake was actually linked to a slight reduction in arrhythmia risk.
This study relied on self-reported data, which can affect the conclusions, but the size of the study helps make the findings reliable. A lot more work would have to be done to show why coffee may be reducing arrhythmia risk.
"Only a randomized clinical trial can definitively demonstrate clear effects of coffee or caffeine consumption," Marcus noted. "But our study found no evidence that consuming caffeinated beverages increased the risk of arrhythmia. Coffee's antioxidant and anti-inflammatory properties may play a role, and some properties of caffeine could be protective against some arrhythmias."