A trio of analyses based on the prospective UK Biobank cohort suggest that regular coffee drinking, especially a daily intake of two to three cups, is not only safe for the heart but may be cardioprotective.
People without cardiovascular disease (CVD) with that level of coffee intake, compared with those who weren’t coffee drinkers, showed significantly reduced risks of death and a range of CVD endpoints, the reductions ranging from 8% to 15% over about 10 years.
In a separate analysis, participants with CVD at baseline also showed significantly improved survival with coffee intake of two to three cups daily, and no increased risk of arrhythmias.
In a third cut of the UK Biobank data, the clinical benefits of the same level of coffee drinking were observed whether the coffee consumed was the “instant” kind for reconstitution with water or brewed from ground whole beans.
Some clinicians advise their patients that coffee drinking may trigger or worsen some types of heart disease, observed Peter M. Kistler, MD, the Alfred Hospital and Baker Heart and Diabetes Institute, Melbourne, Australia. But the current analyses suggest that “daily coffee intake should not be discouraged, but rather considered part of a healthy diet.”
Kistler and his colleagues are slated to present the three UK Biobank cohort analyses separately at the American College of Cardiology (ACC) 2022 Scientific Session, to be held both virtually and in person in Washington, DC, starting April 2. He presented some of the data and commented on them at a press conference held in advance of the meeting.
UK Biobank study participants, who were on average in their late 50s, reported their level of daily coffee intake and preferred type of coffee on questionnaires. The researchers observed generally U-shaped relationships between daily number of cups of coffee and incident CVD, heart failure, coronary heart disease (CHD), stroke, atrial fibrillation, any arrythmia, and death over 10 years.
“This is music to I think many of our patients’ ears, as well as many in the field of cardiology, as those of us that wake up early and stay up late in the hospital consume a fair amount of coffee,” observed Katie Berlacher, MD, associate chief of cardiology education at the University of Pittsburgh Medical Center, Pennsylvania.
The analyses were based on a large cohort and saw a consistent pattern for several cardiovascular outcomes, observed Berlacher, incoming ACC Scientific Session vice chair.
The findings could have a “profound impact in daily clinical care, as many of us caution patients who have or are at risk for having CV[D] against coffee consumption,” she told theheart.org | Medscape Cardiology by email.
“These studies suggest that we do not have objective evidence to caution nor ask patients to stop drinking coffee, including patients who have arrhythmias.”
But importantly, “these studies are not causal,” she added. “So we cannot go so far as to recommend coffee consumption, though one could posit that randomized prospective studies should be done to elucidate causation.”
Coffee, Kistler observed, “is the most common cognitive enhancer. It wakes you up, makes you mentally sharper, and it’s a very important component of many people’s daily lives,” Kistler said by email to theheart.org | Medscape Cardiology. “The take-home message,” he said, “is that clinicians should NOT advise patients to stop drinking coffee up to three cups per day.”
Also, “in non–coffee drinkers, we do not have the data to suggest they should start drinking coffee,” he said. Moreover, people shouldn’t necessarily increase their coffee intake, particularly if it makes them feel anxious or uncomfortable.
Benefits With or Without Known Heart Disease
The researchers identified 382,535 participants in the UK Biobank cohort who were free of CVD at baseline. Their median age was 57, and 52% were women.
Those who reported regular daily intake of two to three cups of coffee, compared with those who were not coffee drinkers, showed significantly reduced risks of CVD, CHD, heart failure, arrhythmias, and death from any cause over 10 years (P < .01 for all endpoints). The hazard ratios (HR) and 95% CI were:
HR, 0.91; 95% CI, 0.88-0.94 for CV disease
HR, 0.90; 95% CI, 0.87-0.93 for CHD
HR, 0.85; 95% CI, 0.81-0.90 for heart failure
HR, 0.92; 95% CI, 0.88-0.95 for arrhythmia
HR, 0.86; 95% CI, 0.83-0.90 for death from any cause
The risk of CVD death hit its lowest point at an intake of one cup per day (HR, 0.83; 95% CI, 0.75-0.93). The risk of stroke was lowest at less than one cup per day (HR, 0.85; 95% CI, 0.75-0.96).
A separate analysis found similar outcomes among a different subset of UK Biobank participants with recognized CVD at baseline. Among 34,279 such persons, those who drank two to three cups of coffee per day, compared with non–coffee drinkers, showed a reduced risk of death over 10 years (HR, 0.92; 95% CI, 0.86-0.99; P = .03).
Among the 24,111 persons diagnosed with arrhythmias at baseline, the lowest mortality risk was observed at one cup per day (HR, 0.85; 95% CI, 0.78-0.94; P < .01). Among those with atrial fibrillation or atrial flutter, one cup per day was associated with a mortality HR of 0.82 (95% CI, 0.73-0.93; P < .01).
In still another analysis of UK Biobank cohort, incident CVD and mortality during the 10-year follow-up was similarly reduced among participants who reported consumption of brewed ground coffee and, separately, instant coffee, compared to non–coffee drinkers. Decaffeinated coffee showed a mostly neutral or inconsistent effect on the clinical endpoints.
The lowest CVD risk was observed at two to three cups per day among those regularly drinking ground coffee (HR, 0.83; 95% CI, 0.79-0.87) and those predominantly taking instant coffee (HR, 0.91; 95% CI, 0.88-0.95).
Potential Mechanisms, Study Limitations
“Caffeine blocks adenosine receptors, which may explain its potential mild antiarrhythmic properties,” Kistler said. “Regular coffee drinkers with supraventricular tachycardia coming to the emergency department often need higher adenosine doses to revert.”
Caffeine has a role in weight loss through inhibition of gut fatty acid absorption and increase in basal metabolic rate, Kistler added, and coffee has been associated with a significantly reduced risk of new onset type 2 diabetes.
However, coffee beans contain more than 100 biologically active compounds, he noted. They include antioxidant polyphenols that reduce oxidative stress and modulate metabolism. Better survival with habitual coffee consumption may be related to improved endothelial function, circulating antioxidants, improved insulin sensitivity, or reduced inflammation, the researchers noted.
They acknowledge some limitations to the analyses. Cause and effect can’t be determined from the observational data. Also, a cup of coffee in the UK means about 200 ml to 250 ml of brew, but its actual caffeine content can vary from 90 mg to 250 mg. Also, data regarding added sugar or milk was lacking. And UK Biobank participants are predominantly White, so the findings may not be generalizable to other populations.
American College of Cardiology 2022 Scientific Session.
Effects of Habitual Coffee Consumption on Incident Cardiovascular Disease, Arrhythmia, and Mortality: Findings From UK Biobank. Presented April 3. Abstract.
Regular Coffee Intake is Associated with Improved Mortality in Prevalent Cardiovascular Disease. Presented April 2. Abstract.
Ground, Instant, or Decaffeinated Coffee? Impact of Different Coffee Subtypes on Incident Arrhythmia, Cardiovascular Disease and Mortality. Presented April 3. Abstract.