This beverage may be good for your heart, after all

By Alistair Gardiner
Published August 19, 2021

Key Takeaways

Coffee is one of the most popular drinks in the world. However, as most coffee drinkers know, the science around this caffeinated beverage changes almost as quickly as the menu at Starbucks. On the plus side, research shows that coffee is linked with a lower risk of cardiovascular disease, cancer, diabetes, and overall mortality.

Yet, on the flip side, we’ve long been advised that coffee consumption heightens the risk of cardiac arrhythmias per earlier research—with health experts suggesting avoidance of caffeinated products to lower this risk.

So what’s the truth about this contested drink? The answer, according to research, is promising. In the largest study of its kind, researchers at the University of California, San Francisco (UCSF) have found no evidence that moderate coffee consumption can cause cardiac arrhythmia; in fact, it may do the opposite.

Here’s what the study found, along with a roundup of the data.

Coffee and cardiac arrhythmias

The study, published in JAMA Internal Medicine in July, sought to explore whether caffeine increases the risk of cardiac arrhythmias. In the study’s introduction, the authors noted that many people believe a link exists, despite a dearth of evidence.

To gain a better understanding of the relationship between the consumption of caffeinated drinks and the risk of arrhythmias, researchers analyzed data from 386,258 UK Biobank participants, aged 40–69 years. These participants underwent physical examinations, completed questionnaires, and provided biological samples.

Participants’ daily rates of caffeinated beverage consumption were measured and juxtaposed with any cardiac arrhythmias, including atrial fibrillation or flutter, supraventricular tachycardia, ventricular tachycardia, premature atrial complexes, and premature ventricular complexes.

Over an average follow-up of 4.5 years, researchers found that 16,979 participants developed an incident arrhythmia. After adjusting for demographic factors, comorbid conditions, and lifestyle habits, they concluded that habitual coffee drinkers were less likely to have developed an arrhythmia.

In fact, they found that each additional daily cup of coffee was associated with a 3% lower risk of incident arrhythmia. Their findings suggest a similar association for atrial fibrillation and supraventricular tachycardia.

Habitually drinking coffee was associated with a lower risk of developing arrhythmia, and there was no evidence that genetically mediated caffeine metabolism had an impact on that link.

Flawed research

So where did the presumptive association between arrhythmias and coffee consumption come from? In their conclusion, researchers noted that many of the studies pointing to this association had serious flaws. Some relied on self-reported coffee consumption and were observational, rather than randomized. As a result, their findings were likely confounded by a number of variables.

Studies have not produced evidence to support the association; in fact, many studies are unearthing various health benefits associated with caffeine and coffee, including a reduction in the risk of cancer, diabetes, cardiovascular disease, and overall mortality.

"Our population-based study provides reassurance that common prohibitions against caffeine to reduce arrhythmia risk are likely unwarranted," said Gregory Marcus, MD, a professor of medicine in the Division of Cardiology at UCSF and co-author of the JAMA study, in an article in Science Daily.

“Only a randomized clinical trial can definitively demonstrate clear effects of coffee or caffeine consumption,” Marcus continued. “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.”

But do the findings of this study mean that coffee is categorically good for you? Well, it’s not quite that simple.

Evidence is still mixed

While there is growing evidence that caffeinated beverages don’t cause cardiac arrhythmias, they may still be harming health in other ways. For example, a study published in Clinical Nutrition in January 2021 found that heavy coffee consumption is associated with an increased risk of cardiovascular disease.

Like the above JAMA study, researchers used data from 362,571 UK Biobank participants. They analyzed the relationship between self-reported coffee intake and various plasma lipid profiles including low-density-lipoproteins cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol (total-C), triglycerides, and apolipoproteins A1 and B (ApoA1 and ApoB).

They found a positive dose-dependent relationship between coffee consumption and plasma concentration of LDL-C, ApoB, and total-C. The highest lipid levels were observed in those drinking 6 or more cups of coffee a day, and researchers concluded that long-term, heavy coffee consumption may lead to a poor lipid profile, which could increase individuals’ risk for cardiovascular disease.

On the other hand, an analysis published in Circulation: Heart Failure in February found that drinking a moderate level of caffeinated coffee may reduce the risk of heart failure.

The research involved analyzing the findings of three large heart disease trials, which collectively included 10 years of follow-up observations on more than 21,000 individuals who drank up to 3 cups of coffee daily. Researchers found that, in all three studies, those who drank more coffee had a lower long-term risk of heart failure.

In one of the studies, the risk of heart failure dropped by 5%-12% for each additional daily cup of coffee consumed, in comparison with those who drank no coffee. In another study, those who drank 2 or more cups of coffee a day appeared to have a 30% lower risk of heart failure, in comparison to those who drank one or fewer.

Moderation suggested

While the findings suggest that coffee may be good for heart health, the researchers stressed that there is not yet enough conclusive evidence to recommend increasing coffee consumption as a health boost.

But, based on the research, you can enjoy drinking coffee in moderation alongside a balanced diet—one that includes fruits and vegetables, whole grains, low-fat/non-fat dairy products, and is low in sodium, saturated fat, and added sugars—without feeling guilty.

Click here to learn about the various health effects of coffee vs tea at MDLinx.

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